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Key Points You Must Know About 4140 Steel

4140 steel is a common multi-functional high-quality alloy structural steel that is widely used in machinery, automobiles, tool manufacturing and other fields. It can achieve a tensile strength of approximately 1000 MPa after heat treatment and is known for its impressive strength and toughness, and can be nitrided for maximum wear resistance.

Songshun Steel has been supplying 4140 round steel and plates globally for more than 20 years, and we are committed to providing you with high-quality and reliable AISI 4140 steel. This article will give you an in-depth understanding of the 4140 steel we provide, including its steel equivalent, chemical composition analysis, properties, applications, heat treatment specifications, delivery status and other information.

4140 Steel Equivalent

China GB /T 3077 standard: GB 42CrMo
American ASTM A29/A29M standard: AISI/SAE/ASTM 4140
German EN 10083-3 standard: DIN EN/DIN 42CrMo4 / W-Nr. 1.7225
Japanese JIS G 4053 standard: JIS SCM440
French NF A 35-557 standard: NF EN/NF 42CD4
French NF A 35-557 standard: NF EN/NF 42CD4
British BS 970-3 standard: BS EN/BS 708M40
International ISO 683-18 standard: ISO 42CrMo4

4140 Steel Chemical Composition

DIN 1.2312 steel is a commonly used mold steel with a higher sulfur content and is also equivalent to P20+S steel. It is suitable for manufacturing many types of plastic molds and is an improved 1.2311 steel.

4140 Steel Chemical Composition (%)

Alloy steel 4140 has a medium carbon content, provides good hardness and strength levels, and forms a hardened structure under appropriate heat treatment conditions. 4140 steel has the highest Mn element content, the addition of Mn has a strengthening effect, which is beneficial to improving the toughness, strength, cold workability, fatigue resistance, hardness, etc. of the steel, and also promotes grain refinement. We precisely control the chemical composition of the 4140 material to ensure that it meets customer needs and ensures excellent performance.

AISI 4140 Steel Properties

1. Mechanical properties (quenching + tempering state)

  • Tensile strength (σb): ≥1080MPa
  • Yield point (σs): ≥930MPa
  • Elongation or elongation after break (δ): ≥12%
  • Hardness: ≤217 HB

2. Properties after heat treatment or processing

  • High strength, hardness and hardenability
  • Excellent toughness and fatigue resistance
  • Good weldability and wear resistance
  • Good corrosion resistance
  • Easy to process and not brittle
  • Small deformation during quenching and high yield rate
  • Good gloss after grinding

These properties vary depending on the parameters used in the heat treatment process. You tell us your special technical requirements and our engineers will evaluate them and send you a professional quotation.

4140 Steel Heat Treatment

4140 steel is widely used in automobiles, aerospace, machinery, building structures, oil and gas, manufacturing, etc. It is often used to manufacture various bearings, gears, fasteners, shafts, drill bits, cutting tools, molds, crankshafts, connecting rods, wheel axles, sleeves, valves, engine parts, landing gear, high-pressure vessels, fishing tools, Petrochemical equipment and so on.

  • Quenching
    Usually the quenching temperature range of 4140 steel is 850-900°C, using water, oil or gas medium for quenching and rapid cooling.
  • Tempering
    After quenching, 4140 is reheated to 550-700°C, kept warm for a period of time, and then cooled with water, oil, or still in the air.
  • Annealing
    The annealing temperature of 4140 steel is in the range of 800-850°C, maintained for a period of time until the temperature of the entire section is uniform, and then cooled in the furnace.

Specific heat treatment specifications will vary based on different standards and application requirements.

AISI/ASTM 4140 Steel Supply

Shape types and specifications: Songshun provides various types and specifications of 4140 steel, with a wide variety and complete specifications, and can be cut into the size you require.

Production process: primary refining → LF refining → VD treatment → continuous casting (die casting) → cleaning, heating → rolling → (stacking) → surface inspection → batch → flaw detection → heat treatment → cutting and sampling → performance inspection → warehousing.

Delivery status: usually delivered after hot rolling, cold drawing, Q&T, finishing, annealing, and annealing + other processing methods (peeling, light drawing, grinding or polishing, etc.).

The specific delivery status and form should be determined according to the customer’s needs, and we at Songshun are committed to meeting our customers’ needs.

Frequently Asked Questions About 4140 Steel

1.What is the weldability of 4140 steel?
4140 steel has good weldability, but it is recommended to pay attention to appropriate preheating and subsequent heat treatment before welding. During the welding process, attention should be paid to controlling the welding current, welding speed and other parameters.

2. What effect does surface treatment have on AISI 4140 steel?
The appearance and corrosion resistance of AISI 4140 steel can be improved through surface treatments such as coating, sandblasting, polishing, and grinding.

3.Can SAE 4140 steel be used in high temperature environments?
Yes, but in high temperature applications, the stability and heat resistance of 4140 steel need to be considered and corresponding measures to be protected or improved. Otherwise, annealing or softening may occur in high temperature environments, affecting its mechanical properties.

In summary, by having an in-depth understanding of the comprehensive guidelines for 4140 steel, you can better play its role. Songshun Steel is committed to providing high-quality and competitively priced 4140 steel with more than 20 years of experience. We can provide you with technical support and one-stop solutions. Please feel free to contact us at any time.


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