About: Joann

High-speed steel is a high-alloy steel containing large amounts of carbon (C), tungsten (W), molybdenum (Mo), chromium (Cr), vanadium (V) and other elements. It has high  hardness after heat treatment. When the cutting temperature reaches over 600°C, the hardness does not drop significantly, and the cutting speed of tools made with it can reach 60m/min, hence the name high-speed steel.

M2 is a molybdenum series high-speed steel, which is mostly used to make tools for cutting difficult materials.
M42 is a high-cobalt toughness high-speed steel, mainly used for high-toughness precision wear-resistant hardware cold stamping dies

Both steel have the good toughness , wear-resistance and hardness . But it have some difference between it’s application area , properties and cost . This article mainly compares the differences details between M2 vs M42 steel.

Chemical composition M2 vs M42 steel

Cr is approximately 4% in almost all high-speed steels.

And the biggest difference between M2 and M42 steel is the content of Cobat(Co) and Molybdeum(Mo) and Tungsten(W). Mo and W have a similar effect on the properties of steel. Meanwhile , both Mo and  W are  the most important composition which imporve the toughness of steel . However, since Mo is much more expensive than W, in order to consider the cost in the production of high-speed steel, W is used in most cases, and then Mo is used to replace part of W to improve toughness. This is tungsten Molybdenum high speed steel, like M2, M4, SKH51, SKH55, etc.  All belong to tungsten-molybdenum high-speed steel, and tungsten-molybdenum high-speed steel has a higher overall cost performance.

But there is another element that has a more significant effect on improving hardness than Mo and W,  that is Co. Co does not produce carbides with carbon, but it will dissolve in the steel, greatly improving the hardness of the steel. It is precisely because of the importance of Co that high-speed steel can be directly divided into two categories, cobalt-containing high-speed steel and cobalt-free high-speed steel. The reason is that Co can significantly improve the red hardness of steel, thereby improving the wear resistance of high-speed steel at high temperatures.

Performance difference M2 vs M42 steel

Hardness :

M2 This steel is easy to heat treat, has little decarburization after heat treatment, and can achieve the maximum  Rockwell hardness is HRC65

M42  can be heat treated to a higher hardness (HRC65-67) than any other high-speed steel and achieve the highest level of  hardness.

Wear-resistance:

The addition of Co composition makes M42 much more better wear-resistant than M2.

Toughness

As for toughness, M2 already has very good toughness, but because the Mo content is much higher than M2, M42 has the highest toughness among high-speed steels.

Application difference M2 vs M42 steel

M2 tool steel is the most commonly used high-speed steel.  This steel is easy to heat treat, has little decarburization after heat treatment,  which is mainly used for cutting tools and is suitable for processing under high-speed and high-temperature conditions.

Applications of M2 : drills, reamers, taps, gear cutters, lathe tools, broaches, boring tools, punches, milling cutters, etc.

M42 tool steel adds 7.75%-8.75% cobalt to increase hardness and toughness. At the same time, the addition of cobalt can produce sharper cutting edges and extend tool service life.

Because of this, M42 tool steel is also suitable for machining stainless steel, high hardness and difficult-to-machine alloys in heavy-duty and high-volume applications.

Applications of M42 : milling cutters, broaches, taps, drills, reamers, punches, saws, cutting tools and thread rolling dies.

Cost difference

M2 as a common ordinary high speed steel , the price is cheaper than M42. M42 add Co , more molybdenum. And  becasue of  China lacks cobalt resources, and cobalt high-speed steel like M42 is expensive 5-8 times than  ordinary high-speed steel.

In Conclusion

The main difference between M2 vs M42 is the different alloy composition ratios. M42 has a more complex process and a higher price. Relatively speaking, M42 has higher mechanical performance indicators, better hardness, wear resistance, and impact resistance. . However, M2 is a relatively cost-effective high-speed steel.  If the budget is limited and the performance requirements are not very high, people can choose M2.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

Before understanding powder high-speed steel, we first understand what powder metallurgy is. Powder metallurgy refers to a steel manufacturing process in which fine steel powder is obtained by atomizing molten steel with high-pressure inert gas or high-pressure water, then pressed into shape under high temperature and high pressure, and then sintered. Powder metallurgy high-speed steel also call PMHSS which  is high-speed steel manufactured through powder metallurgy process.

Manufacturing process of Powder metallurgy high speed(PMHSS)

1. 1. Atomized high-speed steel: First, pour the high-speed steel into high-pressure inert gas or high-pressure water to atomize it into fine high-speed steel powder.
   2. Press molding:Put the high-speed steel powder obtained after atomization into a mold and press it into shape under high temperature and high pressure.
   3. Sintering: Put the pressed blank into a sintering furnace and perform sintering treatment to make it completely densified.
   4. Heat treatment: Finally, the sintered blank make heat treatment to adjust its structure and properties.

The difference between Powder metallurgy high speed(PMHSS)and traditional HSS

Wear resistance

Since the particles (powder) of PMHSS are small and uniform, there will be no uneven solidification, and the internal structure is uniform and stable. Therefore, under the same heat treatment and quenching temperature, the wear resistance of PMHSS will be better than  ordinary HSS.

Purity

Before PMHSS is prepared and formed, its raw materials (powder) will be strictly filtered and screened. This will completely remove impurities and non-metallic substances from the raw material. At the same time, the composition of PMHSS is stabilized after molding to ensure product quality.

No directionality

Powder metallurgy high-speed steel(PMHSS) is made of extremely small particles (powder) that are pressed and sintered, so the performance and strength of all parts of the entire product will be the same. There will be no horizontal or vertical organizational structure like ordinary high-speed steel. Therefore, the overall performance of the entire product also be higher.

Regular deformation

Although powdered high-speed steel has a special structure, dimensional deformation will also occur during the heat treatment process. However, compared with the irregular deformation of ordinary high-speed steel, PMHSS will cause regular deformation of the entire product. In other words, during the heat treatment process of grinding high-speed steel, all parts will become larger at the same time.

Difference in price

The production process of powder metallurgy high-speed steel is complex and the cost is high.

PMHSS is generally 4 to 8 times more expensive than ordinary high-speed steel, so it is usually used to manufacture precision and complex tools or tools for CNC machine tools.

However, the performance of cutting tools made of PMHSS is better than that of ordinary HSS, and the service life is longer than that of ordinary HSS (generally 2 to 3 times).

Application of Powder metallurgy high speed (PMHSS)

• Powder metallurgy high speed steel has good mechanical properties. Suitable for manufacturing: tools that are prone to chipping under intermittent cutting conditions, tools with high strength and sharp cutting edges. Such as gear shaper cutters, hobs, milling cutters, and tools used under high-pressure dynamic loads.
• It has small carbide segregation, fine grains and good wear resistance. Suitable for manufacturing: large-size knives, precision knives, complex knives.
• This type of material has high thermal hardness at high temperatures and is suitable for making tools for difficult-to-machine materials. It is indeed comprehensive.

The development of Powder metallurgy high speed in China

Although China is a major producer of high-speed steel cutting tools, with output and export volume ranking first in the world, China’s high-speed steel industry is still limited by technical barriers and other factors. Currently, the high-end high-speed steel market is still monopolized by overseas brands. At present, most of the powdered metallurgy high-speed steel (PMHSS) is still imported into China.

Due to the high price, many users cannot afford the high cost. In recent years, China has also begun to develop Chinese powder high-speed steel, such as TG’s TPM330. The following is a comparison of the chemical composition of TPM330 with ASP23 and M3-2

Although China’s TPM330 cannot completely replace ASP23 at present, it is undoubtedly the most cost-effective choice. Under the use conditions of some punch materials, the national standard TPM330 also has a longer service life and better performance than ordinary ones such as M2, M42, and DC53. However, for IC packaging molds and complex-shaped workpieces, you can only choose ASP23 because the purity cannot reach  TG. TG is the third generation of powder metallurgy, and ASP is the fifth generation.

In conclusion

The special and advanced smelting method of PMHSS is an innovation in high-speed steel smelting, which creates a new steel type with properties between cemented carbide and ordinary HSS. The rise of PMHSS has brought new breakthroughs in tool materials for the machinery manufacturing and processing industry. As a new steel type with excellent performance, it has gradually been recognized, accepted and loved by people, and is playing an increasingly important role in the machinery industry.

In short, PMHSS is a very excellent high-performance steel with fine grain structure, high wear resistance, high toughness and other characteristics. And is suitable for high-precision and high-efficiency processing applications.

It can be used not only to manufacture various types of tools and cutters, but also to manufacture high-quality mechanical parts and bearings, etc. In the future, with the continuous development of powder metallurgy technology, it is believed that the application scope of  PMHSS will be further expanded.

Currently , Otai stock PMHSS  TPM330 flat bar size

150*200/ 150*300 /200*200 /200*300

If you want to know more about the PMHSS information and the TPM330 stock , please contact

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

Hot rolled and forged are two normal process method for steel .

What is hot rolling:

The metal blank is passed through the gap between a pair of rotating rollers (in various shapes). Due to the compression of the rollers, the cross section of the material is reduced and the length is increased. This is the most common production method for producing steel. It is mainly used to produce profiles, Plates and pipes. At present, the most common one is continuous casting and rolled.

Advantages of hot rolled

It can destroy the casting structure of the steel ingot, refine the grains of the steel, and eliminate defects in the microstructure, thereby making the steel structure dense and improving the mechanical properties. This improvement is mainly reflected in the rolled direction, so that the steel is no longer isotropic to a certain extent; bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.

Disadvantages of hot rolled

• After rolled, the non-metallic inclusions (mainly sulfides, oxides, and silicates) inside the steel are pressed into thin sheets, resulting in delamination (sandwiching). Delamination greatly deteriorates the tensile properties of the steel along the thickness direction and may cause interlaminar tearing as the weld shrinks. The local strain induced by weld shrinkage often reaches several times the yield point strain, which is much larger than the strain caused by load.
• Residual stress caused by uneven cooling. Residual stress is the internal self-balanced stress in the absence of external force. Hot-rolled steel sections of various sections have such residual stress. Generally, the larger the cross-section size of the section steel, the greater the residual stress. Although residual stress is self-balanced, it still has a certain impact on the performance of steel components under the action of external forces. For example, it may have adverse effects on deformation, stability, fatigue resistance, etc.
• Hot-rolled steel products are difficult to control in terms of thickness and edge width. We are familiar with thermal expansion and contraction. Even if the length and thickness are up to standard after hot rolled at the beginning, there will still be a certain negative difference after cooling. The wider the side width and the thicker the thickness, the more obvious this negative difference will be. Therefore, for large-sized steel, the side width, thickness, length, angle, and edge lines of the steel cannot be too precise.

What is forged:

It is a processing method that uses forged machinery to exert pressure on metal blanks to cause plastic deformation to obtain forgings with certain mechanical properties, shapes and sizes. It is one of the two major components of forged (forging and stamping).

Forging can eliminate defects such as loose as-cast metal produced during the smelting process and optimize the microstructure. At the same time, due to the preservation of complete metal streamlines, the mechanical properties of forged are generally better than castings of the same material. Important parts in related machinery with high loads and severe working conditions mostly use forged, except for simple shapes that can be rolled plates, profiles or welded parts.

Advantages of forged

• Changes in mechanical properties: Compared with forged and castings, metal can improve its organizational structure and mechanical properties after forged. After the casting structure is deformed by hot processing by the forged method, due to the deformation and recrystallization of the metal, the original coarse dendrites and columnar grains change into an equiaxed recrystallization structure with finer grains and uniform size, causing the original segregation and recrystallization in the steel ingot. The porosity, pores, slag inclusions, etc. are compacted and welded, and the structure becomes denser, improving the plasticity and mechanical properties of the metal.
• Longer service life: In addition, the forging process can ensure the continuity of the metal fiber structure, so that the fiber structure of the forging is consistent with the shape of the forging, and the metal streamlines are complete, ensuring that the parts have good mechanical properties and long service life. Forgings produced by precision die forging, cold extrusion, warm extrusion and other processes

Disadvantages of forged

• The surface is rough. After forging, the oxide layer is often easily formed on the surface of the steel and the parts are uneven, resulting in uneven surface appearance and large tolerances.
• The cost is higher. Due to the relatively low production efficiency of forging processing and the relatively high performance requirements, the yield rate is lower than other methods, so the production cost is more expensive than ordinary processing methods.

Comparison between hot rolled and forged

• Different processing methods: hot rolled is continuous production, formed by two-way pressure rolled, usually continuous casting and rolling; forged is discontinuous production, usually three-way stress
• The organizational structure is different. The internal structure of forging is relatively denser, so there are relatively fewer porosity and shrinkage defects, so the strength and polishing performance are superior. Therefore, there is a difference in the use of forged and hot-rolled materials. For example: 1.2311, 718 forged plates, customers require etching treatment, and it is generally recommended that customers use forged materials because they are loose, shrinkage, and dense inside. sex is better
• The appearance, size and tolerance are different. The hot-rolled appearance is smoother and more uniform, and the tolerance is smaller. The thickness tolerance of the rolled plate is about 0-2mm. The tolerance of the round steel is determined according to the size, but it is generally within 0-3mm; overall forged.Generally speaking, the surface is rough and the tolerance range is also large, generally 0-5mm.
• The service life of the two is different, because the difference between the transverse and radial mechanical properties of forged is small, that is to say, the isotropy of forged is much higher than that of rolled parts, so the service life of forged is much longer higher than rolled products.
• In terms of processing costs, the cost of forged is much higher than the cost of ho rolled. For some key parts, workpieces that bear large loads or impacts, workpieces with complex shapes or very strict requirements, the forging process must still be used. processed.

How to choose?

•  Generally alloy steels such as 4140, 4340, 8620, carbon steels such as 1020, 1045, 1050, etc., with a diameter/thickness of 300mm or more are forged. If it is tool steel, such as 1.2379/D2, 1.2344/H13, O1/1.2550, etc., Diameter/thickness above 60mm are all forged. Choose forged or hot rolled according to the required size.
•  If it is used in important mold parts or parts that bear greater impact, such as the mold core, you need to choose forged. However, if you need to control costs, you can choose hot-rolled materials in some less important parts, such as the mold frame.
• Choose a suitable and stable supplier. A stable supplier can recommend the most suitable products to customers based on the uses and requirements of the products they need. Aotai Special Steel has been in the steel industry for more than 25 years and has professional product knowledge. Its inventory of 4140/42CrMo4 exceeds 3,000 tons and tool steel exceeds 1,000 tons. It also supplies stainless steel, high-speed steel, and carbon steel.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

Will stainless steel rust? At first glance, it seems to be a false proposition.  But stainless steel rust is everywhere in life, such as the picture below!

Why does iron rust?

When iron is exposed to the air, it reacts chemically with oxygen and moisture to produce various iron oxides, which is manifested as “rust”!

What is stainless steel?

Different from normal steels , stainless steel is a type of steel that has the ability to resist atmospheric oxidation and also has the ability to resist corrosion in media containing acids, alkalis, and salts!

Introduction to stainless steel

In layman’s terms, stainless steel is steel that does not rust easily. In fact, some stainless steel has both rust resistance and acid resistance (corrosion resistance). The rustlessness and corrosion resistance of stainless steel are due to the formation of a chromium-rich oxide film (passivation film) on its surface. This film isolates the metal from the external medium, prevents the metal from being further corroded, and has the ability to repair itself. , if once damaged, the chromium in the steel will regenerate a passivation film with the oxygen in the medium to continue to play a protective role.

The decisive factor in the stainlessness of stainless steel is the chromium content. It is reported that the standards of European and American countries stipulate that the minimum chromium content cannot be less than 10.5%, Japan’s stipulation is 11%, and China’s is 12%.

Stainless steel classification

There are five basic types of stainless steel: austenitic, ferritic, martensite, duplex stainless steel, and precipitation hardening stainless steel.

There are five basic types of stainless steel: austenitic, ferritic, martensite, duplex stainless steel, and precipitation hardening stainless steel.

(1) Austenitic stainless steel is non-magnetic. The typical steel type is added with 18% chromium and contains a certain amount of nickel to increase corrosion resistance. They are widely used steel types.

(2) Ferrite is magnetic and its main content is chromium, with a proportion of 17%. This material has good oxidation resistance.

(3) Martensitic stainless steel is also magnetic. The chromium content is usually 13% and contains an appropriate proportion of carbon.

(4) Duplex stainless steel has a mixed structure of ferrite and austenite. The chromium content is between 18% and 28%, and the nickel content is between 4.5% and 8%. They have great resistance to chloride corrosion. Good results.

(5) The conventional chromium content of precipitated stainless steel is 17, with a certain amount of nickel, copper and niobium added, which can be hardened through precipitation and aging.

According to the metallographic structure, it can be divided into:

1.  Ferritic stainless steel (400 series), which is chromium stainless steel, the main representatives are 420, 440, etc.;
2. Austenitic stainless steel (300 series), chromium-nickel stainless steel, the main representatives are 304, 316, 321, etc.;
3. Martensite Stainless steel (200 series), chromium-manganese stainless steel, high carbon content, the main representatives are 1Gr13, etc.

Why stainless steel resists rust

Elements such as nickel and nickel are added to the surface of stainless steel to form an extremely thin, strong, fine, and stable chromium-rich oxide film (protective film), which prevents oxygen atoms from continuing to penetrate and oxidize, thereby gaining the ability to resist rust.

Why does stainless steel also rust?

Stainless steel will rust when the dense oxide protective layer is destroyed.

Under what conditions will the protective film be damaged?

• Bleaching powder
• Mechanical wear
• Water

Application areas of stainless steel

There are many types of stainless steel, with different properties and different use environments.

301—Good ductility, used for molded products. It can also be hardened by mechanical processing with good weldability. Furthermore，wear resistance and fatigue strength are better than 304 stainless steel.

302—The corrosion resistance is the same as that of 304, but its strength is better due to its relatively higher carbon content. Often used in the food industry

316—Compare with 304, the 316  most widely used steel type, mainly used in the food industry and surgical equipment, the addition of molybdenum gives it a special structure that resists corrosion. Because it has better resistance to chloride corrosion than 304, it is also used as “marine steel”. SS316 is usually used in nuclear fuel recovery devices.

420—”Cutting grade” martensitic steel, similar to Brinell high chromium steel, the earliest stainless steel. Also used in surgical knives, which can be made very shiny.

430—ferritic stainless steel, for decorative purposes, such as automotive accessories. Good formability, but poor temperature resistance and corrosion resistance.

440—High-strength cutting tool steel with slightly higher carbon content. After appropriate heat treatment, it can obtain higher yield strength and its hardness can reach 58HRC, which is among the hardest stainless steels. The most common application example is “razor blades”. There are three commonly used models: 440A, 440B, 440C, and 440F (easy-to-process type).

In addition to 300 series and 400 series, there are also 500 series – heat-resistant chromium alloy steel, 600 series – martensitic precipitation hardening stainless steel

Stainless steel materials may rust due to the following reasons:

 There are chloride ions in the use environment

Chloride ions exist widely, such as table salt/sweat stains/sea water/sea breeze/soil, etc. Stainless steel corrodes very quickly in the presence of chloride ions, even more than ordinary low carbon steel. Therefore, there are requirements for the environment in which stainless steel is used, and it needs to be wiped frequently to remove dust and keep it clean and dry. (This would give him an “inappropriate use” rating.)

Without solid solution treatment

The alloy elements are not dissolved into the matrix, resulting in a low alloy content in the matrix structure and poor corrosion resistance.

Natural intergranular corrosion

This titanium- and niobium-free material is prone to intergranular corrosion.

The most common ways to destroy the passive film of stainless steel in daily life are as follows:

1. Dust containing other metal elements or attachments of heterogeneous metal particles accumulate on the surface of stainless steel. In humid air, the condensed water between the attachments and stainless steel connects the two into a micro-battery, triggering an electrochemical reaction. , the protective film is damaged, which is called electrochemical corrosion.

2. Organic juice (such as vegetables, noodle soup, etc.) adheres to the surface of stainless steel. In the presence of water and oxygen, it forms organic acid. For a long time, the organic acid corrodes the metal surface.

3. The surface of stainless steel contains acid, alkali, and salt substances (such as alkaline water and lime water splash on the wall decoration), causing local corrosion.

4. In polluted air (such as an atmosphere containing a large amount of sulfides, carbon oxides, and nitrogen oxides), when encountering condensed water, sulfuric acid, nitric acid, and acetic acid liquid points will form, causing chemical corrosion.

To ensure that metal surfaces are permanently bright and free from rust, here are some suggestions:

1. The surface of decorative stainless steel must be cleaned and scrubbed frequently to remove attachments and eliminate external factors that cause modification.

2. 316 stainless steel should be used in seaside areas. 316 material can resist seawater corrosion.

3. The chemical composition of some stainless steel pipes on the market cannot meet the corresponding national standards and cannot meet the 304 material requirements. Therefore, it will also cause rust, which requires users to carefully choose products from reputable manufacturers.

So stainless steel is not that it will not rust, but it is not easy to rust!

If  you want to know more information about stainless steel ,please do not hesitate contact us.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

In modern industry, 32CrMoV12-10 steel belong to alloy steel , which play a crucial role because they have high strength, good heat treatment properties and excellent corrosion resistance. 32CrMoV12-10 also know as 1.7765  which under the DIN standard , it is a high-quality material that works under high load and high temperature conditions. It plays a decisive role in industrial operations.

Chemical composition about 32CrMoV12-10 steel

32CrMoV12-10 container  proper pencent  Chromium , it improved its corrosion resistance and extended service life.

32CrMoV12-10 steel delivery condition

As usual ,32CrMoV12-10 steel delivery as QT condition

Mechanical properties

Heat treatment about 32CrMoV12-10

Forging

– Slowly heat 32CrMoV12-10 steel material to 1100-850°C. Due to the relatively high thermal strength of this steel, the initial hammer blow should be light.

Annealing

– Annealing temperature:Heat to approx. 720°C, cool slowly.

– Hardness :Maximum  224 HB

Quenching:

-Quenching temperature: 860-890℃
-Medium: oil, water or air
-Hardness: 53-58 HRC

Tempering:

– Tempering temperature: 540-680℃
– Hardness: ≤45 HRC
– Tempering time: Depends on specific materials and requirements

Application area

32CrMoV12-10 is often used to manufacture equipment and parts that operate under high load and high temperature, such as automobile engine connecting rods, mechanical tool blades, pneumatic tools, molds, and weapon manufacturing, such as gun barrels, etc.

Advantages and features of 32CrMoV12-10

• High strength: 32CrMoV12-10 has excellent tensile strength and yield strength, and is suitable for working environments that bear large loads and pressures.
• Good heat treatment performance: This alloy steel can adjust the hardness and toughness of the material through quenching and tempering processes to adapt to different usage requirements.
• Excellent corrosion resistance: 32CrMoV12-10 adds an appropriate amount of chromium to improve its corrosion resistance and extend its service life.

If you want to know more about the 32CrMoV12-10 or want to get a quotation , please do not hesitate contact us .

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

Cr in steel is one of the main composition  composing steel, and its content directly affects the corrosion resistance and hardenability of steel. What are the main effects of Cr in steel? Last artical we talked about the relationship between Nickel(Ni) and steel. This article details the properties, microstructure, and application of Cr on steel.

Chromium（Cr） on the microstructure and heat treatment of steel

• Chromium and iron can form a continuous solid solution and reduce the austenite phase area. Chromium forms various carbides with carbon, and its affinity with carbon is greater than iron and manganese but lower than tungsten, molybdenum, etc.
• Chromium can reduce the concentration of carbon in pearlite and the ultimate solubility of carbon in austenite.
• Slow down the decomposition rate of austenite and significantly improve the hardenability of steel, but also increase the temper brittleness tendency of steel.

The influence of chromium(Cr) on the mechanical properties of steel

• Improve the strength and hardness of steel. Chromium can improve the strength and hardness of carbon steel in its rolling state, and reduce the elongation and area shrinkage. When the chromium content more than  15%, the strength and hardness will decrease, and the elongation and area reduction will increase accordingly. Parts containing chromium steel can easily obtain higher surface processing quality after grinding.
• Chromium can increase the hardenability of steel and have a secondary hardening effect, which can improve the hardness and wear resistance of carbon steel without making the steel brittle. When the content more than 12%, the steel has good high-temperature oxidation resistance and oxidation corrosion resistance, and also increases the thermal strength of the steel, such as Cr12MoV. Chromium is the main alloying element of stainless steel, acid-resistant steel and heat-resistant steel.
• Significantly increase the ductile-brittle transition temperature of steel.
• The impact toughness drops sharply when the chromium content is high.

The influence of chromium(Cr) on the physical, chemical and process properties of steel

• Improve the wear resistance of steel and easily obtain lower surface roughness values. The electroplating industry widely uses chromium plating technology to improve the wear resistance and aesthetics of products, as shown in the figure below.
• Reduce the conductivity and temperature coefficient of resistance of steel.
• Improve the coercive force and residual magnetic induction of steel, and are widely used in the manufacture of permanent magnet steel tools.
• Chromium forms a passivation film on the surface of steel, which significantly improves the corrosion resistance of steel; but when carbides containing chromium precipitate, the corrosion resistance of steel decreases.
•  Improve the oxidation resistance of steel.
• Dendritic segregation is easy to form in chromium steel, which reduces the plasticity of the steel.
• Since chromium reduces the thermal conductivity of steel, one must slowly heat it during hot processing and slowly cool it after forging and rolling.

Application of Chromium(Cr) in Steel

• Chromium is mainly used in alloy structural steel to improve hardenability, and chromium-containing carbides can be formed on the carburized surface to improve its wear resistance.
•  Chromium and other elements are used in spring steel to improve the overall performance of the steel.
• The use of chromium in bearing steel improves wear resistance and has the advantages of small surface roughness after grinding.
• In tool steel and high-speed steel, it mainly use chromium to improve wear resistance, and it has certain advantages such as tempering resistance and toughness.
• Chromium often applicate in combination with manganese, nitrogen, and nickel in stainless steel and heat-resistant steel. When austenitic steel needs to form, there must be a certain ratio between chromium that stabilizes ferrite and manganese and nickel that stabilize austenite. Such as Cr18Ni9, etc.

Want to know more about information about the Cr in steel ? Please contact :

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

We all know that in addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, phosphorus, etc. And Nickel(Ni) and steel have a good relationship when it express some specail properties .Nickel is one of the main elements that improves and enhances the properties of steel. So what is the main role of nickel in steel? This article details the relationship between Nickel(Ni) and steel.

How does Ni affects the microstructure and heat treatment of steel ?

1. Nickel and iron can form infinite solid solutions. Nickel expands the austenite zone of iron and is the main alloy element that forms and stabilizes austenite.
2. Nickel and carbon do not form carbides.
3. Reduce the critical transformation temperature, reduce the diffusion rate of various elements in steel, and improve hardenability.
4. Reduce the carbon content of eutectoid pearlite, its effect is second only to nitrogen but stronger than manganese. It is about half as effective as manganese in reducing the martensitic transformation temperature.

The influence of nickel on the mechanical properties of steel

1. Strengthen ferrite and refine and increase pearlite to improve the strength of steel and have little impact on the plasticity of steel.
2. The carbon content of nickel-containing steel can be appropriately reduced, thus improving the toughness and plasticity.
3. Improve the fatigue properties of steel and reduce the sensitivity of steel to notches.
4.  Since it is not very effective in improving the hardenability and tempering stability of steel, nickel is of little significance to quenched and tempered steel.

The influence of nickel on the physical, chemical and process properties of steel

1.  Greatly reduce the thermal conductivity and electrical conductivity of steel.
2. Steel with a mass fraction of nickel less than 30% is paramagnetic (i.e. non-magnetic steel), and iron-nickel alloys with a mass fraction of nickel greater than 30% are important precision soft magnetic materials.
3.  Steel with a nickel mass fraction of 15%-20% or higher has high corrosion resistance to sulfuric acid and hydrochloric acid, but is not resistant to nitric acid corrosion. In summary, nickel-containing steel has certain corrosion resistance to acids, alkalis and the atmosphere.
4. Austenitic electrodes should be used when welding steel with high nickel content to prevent the occurrence of cracks.
5. Banded structure and white spot defects are prone to occur in nickel-containing steel, which should be prevented in the production process.

Application of Nickel in steel

1. Pure nickel steel is only used when there are particularly high impact toughness or very low working temperature requirements.
2.  Nickel-chromium or nickel-chromium-molybdenum steel used in machinery manufacturing can obtain comprehensive mechanical properties with good strength and toughness after heat treatment. Nickel-containing steel is particularly suitable for parts that require surface carburization, as shown in the figure. a) Cam mechanism shaft b) Drive shaft
3. Nickel is an austenitizing element in high-alloy austenitic stainless heat-resistant steel, which can provide good comprehensive properties. It is mainly Ni-Cr series steel ，also know as stainless steel, such as 304 stainless steel
4. Since nickel is relatively scarce and an important strategic material, it is relatively expensive. Therefore, it will be used unless it is impossible to meet the performance requirements with other alloy elements. If you are pursuing cost-effectiveness, you can choose the steel with nickel-free or with a less nickel content to instead.

In conclusion

1. Nickel strengthens steel, increasing strength without compromising plasticity.
2. Nickel boosts strength in low carbon steel without sacrificing toughness.
3. Nickel enhances steel strength with minimal impact on toughness and plasticity.
4. Nickel in medium carbon steel reduces pearlite, increasing strength or allowing carbon reduction to enhance toughness.
5. Nickel improves steel fatigue resistance and reduces notch sensitivity.
6. Nickel lowers low-temperature brittleness, enhancing steel toughness for cold applications.
7. High nickel content alters iron-nickel alloy expansion coefficients, useful for specialized materials.
8. Nickel in steel provides corrosion resistance to acids, alkalis, atmosphere, and salt, vital for stainless steel.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

1.4112 is a high-carbon, high-chromium member of the stainless steel series. Due to its high carbon content, it provides high mechanical strength values as well as corrosion resistance after heat treatment. Good hardening and wear resistance. But it also sacrifices corrosion resistance due to the higher carbon content . 1.4112(X90CrMoV18) commonly known as AISI 440B.

Standard:

DIN EN 10088-3

Chemical composition

1.4112 material has a good capability of getting hardness. It containes ~%0.95 carbon element and because of high carbon, this grade is really good grade for high hardness. But since it contains ~%0.95 carbon, its corrosion resistance is not soo good.

Physical properties and mechanical propeties of 1.4112 stainless steel

• Thermal conductivity, λ_20℃: 15 W * m^-1 * K^-1
• Linear expansion coefficient, α = 10,4 * 10^-6 * K^-1
• Heat capacity, c_p = 430 J * kg^-1 * K^-1
• Resistance: 0,8 mkOhm * m
• Modulus of elasticity, E = 215 GPa
• Density = 7,7 g/cm³
• Hardness in annealed condition +1C, +1E, +1D, +1X, +1G, +2D: < 285HB
• Hardness after hardening and tempering of steel 1.4112 : 55-57 HRC

Application of 1.4112 stainless steel

1.4112 stainless steel is used in the manufacture of a variety of cutting tools, bearings, gauges, molds, valve components, blades.  And widely used in measuring instruments that require corrosion resistance in applications requiring both wear and corrosion resistance. Used in glass moulds, pumps and plastics industry.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

When we talk to  choosing the right steel for mould making, the most important is consider the precision and performance . Two popular options of mould steel are 1.2311 and 1.2738 steel. In this article, we’ll  analyzes from the chemical composition, physical properties and mechanical properties,  price, and applications of these two steels , hope to help you make an informed decision.

Chemical Composition 1.2311 VS 1.2738 steel:

1.2311 and 1.2738 steel belong to the category of plastic mould steels and exhibit different chemical compositions that influence their properties.

1.2311 steel, equivalent ASTM P20 steel.In contrast, 1.2738 steel, often referred to as P20+Ni steel, it easlier to find 1.2738 add 0.90%-1.20%  Nickel  base on 1.2311 , it means 1.2738 have a better strength than 1.2311.

Physical Properties 1.2311 VS 1.2738 steel :

Both steels have excellent machinability and polishability, therefore , both  1.2311 and 1.2738 steel are all suitable for mould making.

The little difference is the hardness between them. 1.2311 and 1.2738 steel both are pre-harden steel , but 1.2311 hardness is 28-34HRC , 1.2738 is 30-36HRC.

Mechanical Properties 1.2311 VS 1.2738 steel :

1.2311:

• Tensile Strength: 1050-1200 MPa.
• Yield Strength: 950-1100 MPa.
• Elongation: 15-20%.

1.2738:

• Tensile Strength: 1000-1150 MPa.
• Yield Strength: 900-1050 MPa.
• Elongation: 15-20%.

In summary, both 1.2311 and 1.2738 steel grades have similar tensile and yield strength along with comparable elongation properties, the key difference is their hardness, toughness, and impact resistance. 1.2311 steel offers good wear resistance and dimensional stability with slightly lower hardness, while 1.2738 steel provides improved toughness and impact resistance due to the addition of nickel, making it suitable for applications requiring enhanced mechanical properties under high-stress conditions.

Price compare :

Considering  prices, 1.2311 steel is generally more cost-effective than 1.2738 steel due to differences in their chemical compositions . However, the overall cost may vary depending on factors such as market demand and supplier pricing.

Applications :

1.2311 Steel:

• Widely used for low to medium-volume production of plastic molds, particularly for injection molding applications.
• Suitable for making prototypes and master models due to its good machinability and polishability.
• Often employed in industries such as automotive, consumer goods, and electronics for producing various plastic components and parts.
• Ideal for applications where moderate mechanical strength and wear resistance are required, making it a cost-effective choice for molding applications with lower stress and impact requirements.

1.2738 Steel:

• Preferred for applications requiring higher toughness and impact resistance, especially in large-sized injection molds and tooling for automotive components.
• Well-suited for molds subjected to high-stress conditions and impact loads, such as those encountered in automotive and aerospace industries.
• Due to its enhanced toughness and resistance to deformation under high-stress conditions, 1.2738 steel is commonly used in applications where reliability and durability are paramount.
• Offers superior performance in applications where the mold is subjected to frequent loading and unloading, as well as in situations where molds need to withstand abrasive wear and prolonged use.

In summary, both 1.2311 and 1.2738 steel grades have their respective applications in mold making, the key difference lies in the specific requirements of the application. 1.2311 steel is suitable for low to medium-volume production with moderate mechanical strength requirements, whereas 1.2738 steel is preferred for applications demanding higher toughness and impact resistance, particularly in large-sized molds subjected to high-stress conditions.

Conclusion:

In summary, both 1.2311 and 1.2738 steels offer excellent properties for mould making applications, with slight differences in their chemical compositions, hardness levels, and prices. The choice between the two ultimately depends on specific project requirements, budget considerations, and desired performance characteristics.

Otai special steel stock compelete size of 1.2311, 1.2738 steel, if there is any interest ,please contact below information to get the stock list.

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365

This week, I had a customer inquire with us about several mould steel NAK80, S136 and P20. We knew that these steels would be used in plastic molds, and he wanted to compare the prices of these materials. This article analyzes the differences between the above materials and helps customers choose the most suitable material.

Description of mould steel S136,NAK80 and P20:

S136 steel is chromium-nickel-molybdenum-vanadium alloy steel. As a high-quality plastic mold steel, S136 is widely used in injection molds, extrusion molds, blow molds and other fields. This mold steel has excellent corrosion resistance, polishability, wear resistance, and machinability, making it an ideal choice for manufacturing high-quality, high-precision plastic products.
NAK80 steel  is a kind of pre-hardened plastic mold steel, it is from Japan ,Daido . NAK80 steel generally used for mirror polishing molds, dustproof, TV filter plates, cosmetic boxes, precision wrinkle treatment molds, office automation equipment, auto parts electrical discharge processing molds, etc.
P20 steel  is an American standard pre-harden plastic mold steel. Widely used in China, factory hardness HRC30~42, suitable for large and medium-sized precision molds, suitable for long-term production of high-quality plastic molds, and used for large mold bases. This steel has good machinability and can be generally polished.

Chemical composition difference

Characteristic between mould steel S136 , NAK80 and P20

S136 mold steel

1. Corrosion resistance: It has excellent corrosion resistance and apply  in humid environments for a long time without rusting.
2. High hardness: It has high hardness and can maintain good hardness and wear resistance at high temperatures.
3. Excellent cutting performance: It has good cutting performance and is easy to process and manufacture.
4. Good heat treatment performance: It has good heat treatment performance and can obtain the required hardness and strength through heat treatment.
5.  Excellent wear resistance: It has excellent wear resistance and can maintain good surface finish and dimensional accuracy during long-term use.

NAK80 steel

1.  High hardness: NAK80 mold steel is pre-hardened steel, and its hardness can reach 37-43HRC before leaving the factory.
2.  Excellent polishing performance: very suitable for molds with high surface requirements, such as optical devices or injection molded parts
3. Ease of processing: NAK80 has very good processing performance, is easy to cut, mill and drill, and can meet the requirements of mold processing.
4. Good thermal stability: NAK80 can still maintain stable performance in high-temperature working environments. It has a low thermal expansion coefficient and excellent thermal conductivity, and can effectively resist plastic mold deformation and thermal stress caused by high temperatures.

P20 steel

1. Hardness: Factory pre-hardened, hardness 29-33HRC. Uniform hardness, good polishing performance and photo-etching performance, and good processing performance
2. It has excellent cutting performance and wear resistance, and can withstand high pressure and impact. Suitable for long term mold use.
3. P20 mold steel also has high strength and toughness and can withstand long-term mold work.
4. It has good heat resistance and corrosion resistance, making it the first choice material for plastic injection molds.

Application between mould steel S136 , NAK80 and P20

NAK80  Steel application :

Mould steel NAK80 widely used in plastic injection molds, die-casting molds and precision molds also in industries such as auto parts, home appliances, electronic products, and medical devices.

It is suitable for flat panel displays, cameras, audio equipment, transparent covers, films and other shell molds with mirror polishing requirements.

S136 steel application

S 136 is suitable for plastic molds with high corrosion resistance and mirror polish requirements.

Therefore  the highly smooth surfaces of S136 steel for the production of optical products, such as cameras, sunglasses, chemical instruments and plastic products;

P20 Steel application

• P20 is suitable for plastic molds and mold bases such as TV front casings, telephones, water dispensers, vacuum cleaners, etc.
• Thermoplastic plastic injection molds, extrusion molds.
• Thermoplastic blow molds. Heavy duty mold main components.
• Cold structural parts.
• Commonly used in manufacturing TV casings, washing machines, refrigerator inner casings, buckets, etc.

The difference of price between mould steel S136 , NAK80 and P20

P20 ＜ S136 ＜ NAK80

In conclusion

S136 , NAK80  and P20 are all good material widely used for steel mould.

But there are some application  differences.

• If you need a mold with good polishability and relatively high requirements, you can choose NAK80 steel.
• If you want to produce injection molds or extrusion molds with certain corrosion resistance but also have certain surface requirements, you can choose S136 steel.
• If you have a budget Limited, if the surface requirements are not high, you can choose the more cost-effective P20 steel.

Otai special steel stock more than 1500tons for S136 , NAK80  and P20 steel. If you want to get the stock list and the price details , please contact below information:

Name: Joann

E-mail:joann@otaisteel.com

WhatsApp:+8613128068365