Category Archives: ALLOY STEEL

Steel forms the backbone of modern industry, and among its diverse family, one alloy particularly stands out for its exceptional versatility and strength – 4140 steel. In this comprehensive guide, we’ll delve into  4140 steel, exploring how to find a reliable 4140 steel supplier.

What is 4140 Steel?

4140 steel is a low alloy with high tensile strength, toughness, and excellent wear resistance.

Properties of 4140 Steel

High Tensile Strength: One of the most notable characteristics of 4140 steel is its impressive tensile strength, making it suitable for applications under high-stress conditions. It excels in automotive components or structural elements.

Toughness and Impact Resistance: Its composition grants 4140 steel exceptional toughness, allowing it to withstand impacts and dynamic loading conditions. This property makes it a popular choice in manufacturing gears, axles, and other machinery components.

Good Fatigue Strength: Another key advantage of 4140 steel is its resistance to fatigue. This property is crucial for components subjected to cyclic loading, such as aircraft landing gear or automotive suspension parts.

Excellent Wear Resistance: The inclusion of molybdenum in 4140 steel significantly enhances its wear resistance, making it suitable for tooling applications where abrasion is a concern.

Machinability: Despite its high strength, 4140 steel maintains good machinability when treated properly. This allows for precise and efficient manufacturing processes.

Applications of 4140 Steel

Automotive Industry: The automotive industry heavily relies on 4140 steel. It’s used in a range of components including axles, crankshafts, gears, and connecting rods.

Aerospace Components: Due to its excellent strength-to-weight ratio and fatigue resistance, 4140 steel finds applications in aerospace components like landing gear, shafts, and structural elements.

Oil and Gas Industry: The oil and gas sector often employs 4140 steel in the manufacturing of drill collars, subs, and other downhole equipment, thanks to its combination of strength and corrosion resistance.

Tool and Die Making: 4140 steel’s wear resistance and machinability make it a popular choice for tool and die production, where precision and durability are paramount.

Sourcing 4140 Steel: Choosing the Right Supplier

When it comes to procuring 4140 steel, selecting the right supplier is crucial for ensuring quality and reliability. Look for a supplier with the following attributes:

Reputation and Experience: A reputable supplier has a track record of providing high-quality 4140 steel to various industries. Look for reviews, testimonials, and years in business.

Certifications and Standards: Ensure that the supplier adheres to industry standards and holds relevant certifications, such as ISO 9001 for quality management.

Customization Options: A reliable supplier should offer customization options to meet specific requirements, such as different sizes, shapes, or heat treatments.

Timely Delivery and Logistics: A supplier’s ability to meet delivery deadlines and provide efficient logistics support is crucial for keeping projects on schedule.

Technical Support and Expertise: A reputable supplier should have a team of experts . It can provide technical advice and support throughout the procurement process.

Conclusion

In the world of steel alloys, 4140 steel stands tall for its exceptional properties and wide-ranging applications. Its combination of high strength, toughness, and wear resistance make it a go-to material for industries spanning automotive, aerospace, oil and gas, and tool making. When sourcing 4140 steel, it’s imperative to partner with a trusted supplier who can provide the quality and reliability needed for your projects.

FAQs

Is 4140 steel suitable for welding applications?

Yes, 4140 steel can be welded, but it requires proper preheat and post-weld heat treatment to prevent cracking.

What are the available forms of 4140 steel?

4140 steel is available in various forms, including round bars, flat bars, plates, and seamless tubing.

Can 4140 steel be heat treated for further enhancement of its properties?

Yes, 4140 steel can undergo processes like quenching and tempering to further improve its mechanical properties.

What industries commonly use 4140 steel?

Industries such as automotive, aerospace, oil and gas, and tool and die making frequently utilize 4140 steel for various components.

What are some alternatives to 4140 steel for high-stress applications?

Some alternatives include 4340 steel, 8620 steel, and 6150 steel, which offer similar properties and are often chosen based on specific application requirements.

Dongguan Otai special steel ., Ltd  stock more than 300otons of 4140 steel stock . We have the ISO9001-2022 certificate and accept the third party inspecition like SGS. For delivery time , we delivert 15% faster  than competitiors.

Welcome to inquiry, Contact : Joann , E-mail:joann@otaisteel.com; WhatsApp:+8613128068365

http://www.otaisteel.com

4140 steel bar stands as a stalwart in the realm of metallurgy, playing a pivotal role in various industries.

What is 4140 Steel?

4140 steel is a low alloy steel with good strength and toughtness which we explaine in previous artical.

Chemical composition

Manufacturing Process

The journey of 4140 steel begins with a precise blend of raw materials, which are then subjected to intense heat and pressure through forging and rolling processes. This meticulous treatment refines the steel’s grain structure, enhancing its strength and durability. However, the true magic happens during heat treatment. This critical phase involves controlled heating and rapid quenching, effectively tailoring the steel’s hardness and toughness to meet specific application requirements.

Physical and Mechanical Properties

In the realm of physical attributes, 4140 steel boasts a density of approximately 7.85 g/cm³, rendering it robust yet manageable. Its melting point stands at around 1425°C (2600°F), a testament to its resilience under extreme conditions. Mechanically, this steel variety shines. With a tensile strength of 655 megapascals (MPa) and a yield strength of 415 MPa, it proves itself as a formidable contender for applications demanding exceptional load-bearing capabilities. Furthermore, its impact resistance ensures it stands firm even in the face of sudden, high-stress forces.

Applications of 4140 Steel Bar

Aerospace: In the aerospace sector, where weight is of paramount concern, 4140 steel takes the center stage. Its high strength-to-weight ratio makes it an indispensable material for crafting components that demand both structural integrity and reduced mass. From landing gear to engine parts, 4140 steel plays a vital role in keeping aircraft aloft.

Automotive: Within the automotive industry, 4140 steel finds its calling in the manufacturing of critical components. Axles, gears, and shafts, subjected to intense loads and stresses, benefit immensely from the steel’s robustness. Its ability to withstand wear and fatigue ensures longevity and reliability on the road.

Oil and Gas Industry: In the unforgiving environment of the oil and gas sector, 4140 steel proves its mettle. Utilized in downhole drilling tools, this steel variant exhibits exceptional toughness and wear resistance, enduring the harsh conditions encountered in deep drilling operations.

Manufacturing: From heavy machinery to precision tools, 4140 steel stands as a cornerstone of manufacturing. Its versatility and machinability make it an invaluable asset for crafting a wide array of equipment that drives industrial processes.

Advantages of Using 4140 Steel Bar

In the realm of materials, 4140 steel emerges as a frontrunner for several reasons. Its adaptability is unparalleled, rendering it suitable for an extensive range of applications. Moreover, its cost-effectiveness is a boon to industries seeking durable, long-lasting solutions. By choosing 4140 steel, businesses not only secure top-tier performance but also make a prudent fiscal choice in the long run.

4140 Steel Bar vs. Other Steels

When pitted against other commonly used steels, 4140 steel stands out in various niches. Its superior strength and hardness make it an ideal candidate for applications where resilience is paramount. Compared to its counterparts, 4140 steel offers a compelling blend of properties, ensuring it excels in specific roles where compromise is not an option.

Best Practices for Working with 4140 Steel Bar

Working with 4140 steel demands a nuanced approach to ensure optimal results. When machining, precision is key. Employing proper cutting tools and techniques is essential for achieving the desired outcomes. Welding requires careful consideration of pre- and post-welding procedures to preserve the steel’s integrity. Heat treatment should be approached with meticulous attention to detail, adhering to specified temperature ranges and quenching processes.

Conclusion

In the grand tapestry of metallurgy, 4140 steel stands as a testament to human ingenuity. Its impeccable blend of properties makes it a cornerstone in industries that demand uncompromising performance. From the aerospace heavens to the depths of the earth’s crust in the oil and gas sector, 4140 steel’s versatility knows no bounds. By choosing 4140 steel, industries secure not only a material but a partner in progress.

FAQs

Is 4140 steel bar suitable for high-temperature applications?

While 4140 steel demonstrates exceptional strength, it does have limitations in high-temperature environments. At elevated temperatures, it may experience reduced mechanical properties and could become susceptible to deformation.

What are the potential drawbacks of using 4140 steel?

One consideration when working with 4140 steel is its sensitivity to improper heat treatment. Failing to adhere to precise temperature ranges during heat treatment can result in suboptimal mechanical properties.

Can 4140 steel be coated for corrosion resistance?

Yes, 4140 steel can be coated to enhance its resistance to corrosion. Common coating options include plating, nitriding, and specialized coatings designed for harsh environments.

Are there any special safety precautions when machining 4140 steel?

When machining 4140 steel, it’s crucial to employ proper safety measures. This includes using the appropriate cutting tools, employing adequate ventilation, and wearing personal protective equipment (PPE) to prevent accidents.

Where can one source high-quality 4140 steel bar?

Reputable steel suppliers and manufacturers often offer high-quality 4140 steel bars. It’s recommended to seek out established and well-reviewed suppliers to ensure the material meets industry standards.

More details pls visit our main website: http://www.otaisteel.com

When it talk to widely used and reliable steel, AISI/SAE 4140 steel  should be a top contender. This alloy steel is known for its good strength, long lasting, and adaptability across various industries. In this article, we’ll analyze the details of AISI/SAE 4140 steel, exploring its properties, applications, and the value it brings to engineering and manufacturing processes.

The Basics of AISI/SAE 4140 Steel

AISI/SAE 4140 is a chromium-molybdenum steel wide know for its high tensile strength and excellent toughness. The ’41’ in its name means 0.41% carbon content, while the ’40’ for 0.4% molybdenum content.AISI means American Iron and Steel Institute and SAE means Society of Automotive Engineers , both are Steel Designation System. 

Key Properties of AISI/SAE 4140

High Tensile Strength: AISI/SAE 4140 boasts impressive tensile strength, making it suitable for applications under high-stress conditions.

Good Fatigue Resistance: This steel exhibits excellent fatigue resistance, crucial for components subject to repetitive loading.

Impact Toughness: The combination of chromium and molybdenum enhances its toughness, allowing it to withstand sudden impacts without deformation or fracture.

Machinability: AISI/SAE 4140 can  machine relatively easily, making it a preferred choice in manufacturing processes.

Heat Treatability: It responds well to heat treatment, allowing for a wide range of hardness levels to achieve.

Applications o

Automotive Industry
In the automotive sector, AISI/SAE 4140 is widely used for critical components such as axles, crankshafts, and gears. Its high strength and fatigue resistance make it ideal for withstanding the demands of vehicle operation.

Aerospace Engineering
4140 applicate in aerospace where request safety and reliability , AISI/SAE 4140 finds use in components like landing gear parts, structural elements, and engine components. Its combination of strength and toughness enables it to withstand the harsh aerospace environment

Oil and Gas Industry
The harsh environments of the oil and gas industry require materials that can withstand extreme conditions. AISI/SAE 4140 is a favored choice for components like drilling tools, wellhead equipment, and downhole components due to its excellent mechanical properties.

Construction and Heavy Equipment
In construction and heavy equipment manufacturing, AISI/SAE 4140  use for critical load-bearing components like gears, shafts, and connecting rods. Its high strength-to-weight ratio and durability make it an indispensable material in this industry.

Advantages

Versatility: Its adaptability across various industries and applications make it a versatile material choice.

Cost-Effective: Despite its exceptional properties, AISI/SAE 4140 with competitive price, offering a cost-effective solution for many engineering projects.

Longevity: Components made from AISI/SAE 4140 tend to have a longer service life, reducing maintenance and replacement costs.

Machinability: Its machinability ensures that manufacturing processes are efficient and cost-effective.

Conclusion

AISI/SAE 4140 steel is a powerhouse material in the engineering world, prized for its exceptional properties and versatility across various industries. Its high tensile strength, excellent fatigue resistance, and heat treatability make it a top choice for critical applications. From automotive to aerospace, oil and gas to construction, AISI/SAE 4140 plays a crucial role in shaping modern engineering solutions.

FAQs

1. What does  4140 steel stand for?

AISI/SAE 4140 is a chromium-molybdenum steel known for its high tensile strength and toughness. The numbers in its name represent the carbon and molybdenum content, respectively.

2. How is  4140 steel used in the automotive industry?

AISI/SAE 4140 steel finds extensive use in the automotive sector for critical components like axles, crankshafts, and gears due to its high strength and fatigue resistance.

3. Can  4140 steel be heat-treated?

Yes, AISI/SAE 4140 steel responds well to heat treatment, allowing for a wide range of hardness levels to achieve, enhancing its versatility in various applications.

4. What are the advantages of using AISI/SAE 4140 steel in aerospace engineering?

In aerospace applications, AISI/SAE 4140’s combination of strength and toughness makes it ideal for components like landing gear parts, structural elements, and engine components, ensuring safety and reliability.

5. Is AISI/SAE 4140 steel cost-effective?

Despite its exceptional properties, AISI/SAE 4140 steel with competitive price, offering a cost-effective solution for many engineering projects, making it a popular choice across industries.

A36 and 4140 steel are two distinct types of steel with unique properties and applications. To begin with, understanding their differences is crucial for selecting the right material for specific projects. In this comparison, we’ll delve into the characteristics, applications, and advantages of both A36 and 4140 steel.

Chemical Composition

• A36 Steel:
  • Carbon (C): 0.25%
  • Manganese (Mn): 1.03%
  • Phosphorus (P): 0.04%
  • Sulfur (S): 0.05%
  • Silicon (Si): 0.4%
  • Copper (Cu): 0.2%
• 4140 Steel:
  • Carbon (C): 0.38-0.43%
  • Manganese (Mn): 0.75-1.00%
  • Phosphorus (P): 0.035%
  • Sulfur (S): 0.040%
  • Silicon (Si): 0.15-0.35%
  • Chromium (Cr): 0.80-1.10%
  • Molybdenum (Mo): 0.15-0.25%

The Properties of A36 and 4140 Steel 

• A36 Steel:
  • Tensile Strength: 400-550 MPa (58,000-80,000 psi)
  • Yield Strength: 250 MPa (36,000 psi)
  • Brinell Hardness: 119-162HB
• 4140 Steel:
  • Tensile Strength: 655-760 MPa (95,000-110,000 psi)
  • Yield Strength: 415 MPa (60,000 psi)
  • Brinell Hardness: 197HB

Different Applications of A36 and 4140 Steel 

• A36 Steel:
  • A36 steel is commonly used in construction, structural applications, and general fabrication due to its versatility and relatively low cost. Additionally, it finds wide employment in bridges, buildings, and various types of machinery.
• 4140 Steel:
  • In contrast, 4140 steel is primarily utilized in high-stress applications such as automotive components, gears, axles, and tooling. Furthermore, it proves suitable for parts subjected to high levels of wear and tear.

Heat Treatment

• A36 Steel:
  • Not heat-treatable. It undergoes a mild cold-working process to improve its mechanical properties.
• 4140 Steel:
  • Can be heat-treated to achieve a range of hardness levels, making it highly adaptable for specific applications.

Weldability 

• A36 Steel:
  • Easily weldable, making it suitable for a wide range of applications.
• 4140 Steel:
  • More challenging to weld due to its higher carbon content. Preheating and careful selection of welding procedures are crucial.

Cost Considerations

• A36 Steel:
  • Relatively economical, making it a popular choice for general-purpose applications.
• 4140 Steel:
  • Moderately more expensive than A36 due to its alloying elements, but provides superior performance in high-stress environments.

Conclusion

In summary, A36 and 4140 steel cater to different industries and applications. A36 is versatile and widely used in construction, while 4140 excels in high-stress scenarios, thanks to its impressive strength and heat-treatable properties. Choosing between them depends on the specific requirements of the project.

FAQs

1. Can A36 steel be heat-treated?
   • No, A36 steel is not considered a heat-treatable material.
2. What industries commonly use 4140 steel?
   • 4140 steel finds applications in automotive, aerospace, and oil and gas industries, among others.
3. Is 4140 steel more expensive than A36?
   • Yes, 4140 steel tends to be moderately more expensive due to its alloying elements.
4. What are the primary advantages of A36 steel?
   • A36 steel is known for its versatility, ease of welding, and cost-effectiveness.
5. Can 4140 steel be welded?
   • Yes, 4140 steel can be welded, but it requires specific procedures and precautions due to its higher carbon content.

A36 and 4140 steel both are stock steel in Otai special steel , if you want to know more details about the application and performance of A36 and 4140 steels , pls feel free contact us.

Contact : Joann /E-mail:joann@otaisteel.com /WhatsApp:+8613128068365

Our main Website:http://www.otaisteel.com

Steel is an integral material in various industries, known for its strength and durability. Two popular types, 8620 and 4140 steel, are often used in applications requiring high tensile strength and impact resistance. Let’s delve into the characteristics, applications, and differences between these two steels.

Chemical Composition

8620 Steel:

8620 steel is a low-alloy steel, it’s composition imparts excellent hardenability and toughness.

4140 Steel:

4140 steel, also known as chromoly steel, which we mention the chermical composition in another artical . This mix offers high strength and good machinability.

Mechanical Properties

8620 Steel:

Tensile strength σb (MPa): ≥980

Yield strength σs (MPa): ≥785

Elongation δ5(%): ≥9

Area shrinkage ψ(%): ≥40

Impact power Akv(J): ≥47

Impact toughness value αkv (J/cm2): ≥59

Hardness (annealed or high temperature tempering state): ≤197 HB

4140 Steel:

Tensile strength σb (MPa): ≥1080(110)

Yield strength σs s (MPa): ≥930(95)

Elongation δ5 (%): ≥12

Area shrinkage ψ(%): ≥45

Impact power Akv(J): ≥63

Impact toughness value kv (J/cm2): ≥78(8)

Hardness: ≤217HB

Heat Treatment

Both 8620 and 4140 steel respond well to heat treatment, allowing for tailored mechanical properties. They can be quenched and tempered to achieve specific hardness levels.

Machinability

4140 steel tends to have better machinability compared to 8620 steel. This is due to its lower carbon content, which makes it easier to cut, shape, and drill.

Weldability

8620 steel is more readily weldable compared to 4140 steel. The latter may require preheating and careful consideration during the welding process.

Applications

8620 Steel:

Gears and gearboxes
Aircraft parts
Automotive components
Hydraulic fittings

4140 Steel:

Axles
Shafts
Bolts and nuts
Automotive and motorcycle parts

Cost

Generally, 8620 steel is more affordable compared to 4140 steel. This can be a significant factor in material selection for cost-sensitive projects.

Corrosion Resistance

4140 steel offers better corrosion resistance due to its higher chromium content. However, both steels may require additional coatings or treatments for extended exposure to harsh environments.

Conclusion

In summary, 8620 and 4140 steel are both versatile materials with unique properties. The choice between them depends on the specific requirements of the application. 8620 is chosen for its weldability and cost-effectiveness, while 4140 is preferred for its higher strength and machinability.

FAQs

1. Can 8620 steel be used for high-stress applications?

Yes, 8620 steel is suitable for applications that require high tensile strength and impact resistance.

2. Is 4140 steel more expensive than 8620 steel?

Generally, 4140 steel tends to be pricier due to its higher alloying elements.

3. Can these steels be surface-hardened?

Yes, both 8620 and 4140 steels respond well to surface-hardening processes like carburizing.

4. Which steel is better for applications involving heavy machinery?

For heavy machinery, 4140 steel is often preferred due to its higher tensile strength.

5. Are there any specialized welding considerations for these steels?

Yes, 4140 steel may require preheating and controlled cooling during welding to prevent cracking.
Remember, when choosing between 8620 and 4140 steel, it’s crucial to consider factors such as cost, machinability, and specific mechanical properties required for your project. Always consult with a metallurgist or materials engineer for critical applications.

Know more information , click our mainly website:  http://www.otaisteel.com

1045 and 4140 steel are two of the most common materials used in industrial construction.As we know 1045 is a carbon steel and 4140 steel is a alloy steel.But what is the mainly difference of these two steel ? I introduce in this artical, let’s check.

Composition and Properties

1045 Steel: This is a medium carbon steel, it contain 0.43%-0.50% carbon with a better strength, toughness, and wear resistance. Due to the proper carbon content, it’s relatively easy to machine and weld. It’s usually used in high strength and moderate wear resistance situation.

4140 Steel: We also introduce in last artical . 4140 steel also known as chromoly steel, 4140 contains 0.38%-0.43% carbon along with other alloying elements like chromium and molybdenum. These chermical composition provides excellent strength, hardness, and fatigue resistance. Therefore it’s particularly well-suited for applications that require high tensile strength and good impact resistance.

Strength and Hardness

One of the most significant differences between 1045 and 4140 steel lies in their strength and hardness properties. 4140 steel, with its higher carbon content and alloying elements, offers superior strength and hardness compared to 1045. This makes it a better choice to applicate in high tensile strength and resistance to wear and abrasion.

Machinability

1045 steel with a good machinability. It can be easily cut, turned, drilled, and milled using conventional machining techniques. On the other hand, 4140 steel, while still machinable, requires a long time machine efficiently and specialized tools due to its higher hardness.

Weldability

Both 1045 and 4140 steel can be welded, but 1045 is generally considered to have better weldability. Its lower carbon content reduces the risk of cracking during welding. 4140 steel, with its higher carbon content and alloying elements, requires preheating and post-welding stress relief to minimize the risk of cracking.

Heat Treatment

Both steels reflect well to heat treatment, allowing for a wide range of hardness and strength levels to be achieved. This versatility makes them suitable for a variety of applications.

Otai stock 1045 and 4140 steel more than 3000 tons . If you have interest , you can visit our mainly website ：http://www.otaisteel.com

4140 and 4340 steel are relatively common alloy steels. So what is the difference between these two types of steel? This article briefly analyzes the differences between 4140 and 4340 steel plates.

Composition and Properties:

Both 4340 and 4140 steels belong to the alloy steel category and are composed of similar elements. The main composition of steel are iron, carbon, chromium, molybdenum and manganese. The difference between different steel types  mainly based on the content of chemical compositions.

4340 Steel: This alloy contains a higher percentage of nickel and molybdenum compared to 4140 steel. This results in superior toughness and fatigue resistance, making it an excellent choice for applications involving heavy loads and high-stress conditions.

4140 Steel: While still a robust steel, 4140 has a lower concentration of nickel and molybdenum. It is known for its exceptional hardness, making it suitable for applications where wear resistance is crucial.

Applications:

The choice between 4340 and 4140 steel depends largely on the specific requirements of the application:

4340 Steel Applications:

Aerospace components like landing gear and structural parts.
Crankshafts and other components in automotive and racing industries.
Oil and gas drilling equipment due to its high strength and toughness.

4140 Steel Applications:

Gears, shafts, and spindles in machinery and equipment.
Automotive parts such as axles, bolts, and connecting rods.
Firearms components due to its excellent hardness and impact resistance.

Machinability:

4340 : Compared to 4140 steel, 4340 contains a higher composition of nickel and molybdenum. This results in better toughness and fatigue resistance, making it an excellent choice for applications involving heavy loads and high stress conditions.

4140 :4140 is known for its good machinability and can be easily machined using standard machining processes. This makes it the first choice for applications requiring complex shapes and precision.

Heat Treatment:

Both steels respond well to various heat treatment processes, allowing for customization of their mechanical properties. They can be hardened through processes like quenching and tempering to achieve specific levels of hardness and toughness.

Cost Considerations:

In terms of cost, 4140 steel tends to more economical than 4340. This is primarily due to the higher alloy content of 4340, which makes it more expensive to produce.

Conclusion:

In summary, 4340 and 4140 steels are both excellent choices for different applications depending on the specific requirements. 4340 offers superior toughness and fatigue resistance, making it ideal for high-stress applications like aerospace components. On the other hand, 4140  prize its hardness and wear resistance, making it a top choice for gears and automotive parts.

FAQs:

Can 4340 and 4140 steel be welded?

Yes, both steels can  weld  using conventional welding techniques. However, it’s essential to follow proper welding procedures to maintain the integrity of the material.

Which steel better suit for high temperature applications?

With higher nickel and molybdenum content, 4340 steel has enhanced heat resistance, making it better suited for high-temperature applications.

Are there any restrictions on the size or shape of parts made from these steels?

While both steels use to produce a variety of components, factors such as machinability and heat treatment may affect the feasibility of certain shapes or sizes.

Do 4340 and 4140 steel require special storage or maintenance considerations?

These steels should be stored in a dry environment to prevent corrosion. Additionally, applying an appropriate rust inhibitor can help prolong their lifespan.

Can these steels use interchangeably in certain applications?

In some cases, yes. However, it’s crucial to consider the specific demands of the application and choose the steel that best aligns with those requirements.
Remember, before choosing between 4340 and 4140 steel, it’s essential to evaluate the specific needs of your application to ensure the optimal material selection.
Otai special steel is the largest 4140 stockist in South of China ,if you want to know more information about the 4140 and 4340 , pls feel free contact us.

 Joann，E-mail：joann@otaisteel.com ;WhatsApp:+8613128068365

http://www.otaisteel.com

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