What is 4140 steel?
Steel 4140 (G41400) belongs to ultra-high-strength steel, and the executive standard is ASTM A29M UNS-2012 (standard specification for general requirements of hot-forged carbon steel and alloy steel bars).
This steel has good machinability, small deformation during processing and good fatigue resistance, being a steel of medium and high hardenability.
This steel has good workability.
The processing deformation is small and the fatigue resistance is quite good.
It is a steel of medium hardenability.
4140 has good strength and comprehensive mechanical properties after heat treatment, as well as good processability and high yield.
Maximum operating temperature is 427℃
4140 has high strength, hardenability, good toughness, small deformation during quenching, no obvious brittleness in tempering, high fatigue limit and multiple impact resistance after quenching and tempering treatment, and good low-temperature impact toughness.
It has high creep resistance and high temperature resistance.
It is used to manufacture forged parts with higher strength and larger quenching and tempering cross-section than 35CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axle, connecting rod and spring clamp with large load, gasket drill pipe and fishing tool for oil at depths well below 2,000 m and mold for press brake.
Chemical composition of 4140 steel
| Element | Composition |
|---|---|
| Carbon (C) | 0.38 – 0.45 |
| Silicon (Si) | 0.17 – 0.37 |
| Manganese (Mn) | 0.50 – 0.80 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 0.9 – 1.20 |
| Nickel (Ni) | ≤ 0.30 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Copper (Cu) | ≤ 0.30 |
Mechanical Properties of 4140 Steel
| Mechanical property | Specification |
|---|---|
| Tensile strength (σb) (MPa) | ≥ 1080 (110) |
| Yield resistance (σs) (MPa) | ≥ 930 (95) |
| Elongation (δ5) (%) | ≥ 12 |
| Area Reduction (ψ) (%) | ≥ 45 |
| Akv Impact Energy (J) | ≥ 63 |
| Impact Resistance (αkv) (J/cm²) | ≥ 78 (8) |
| Hardness (HB) | ≤ 217 |
| Sample size | 25mm blank size |
What is 4130 steel?
Alloy steel AISI 4130 (UNS G41300), executive standard: ASTM A29/A29M-04.
4130 structural steel has high strength and toughness, high hardenability, and the critical oil hardenability diameter is 15-70mm;
The thermal resistance of steel is also good. It has sufficient resistance to high temperatures below 500 ℃, but its resistance decreases significantly at 550 ℃;
When the alloy element is at the lower limit, the welding is quite good, but when it is close to the upper limit, the weldability is average and it needs to be preheated above 175°C before welding;
Steel has good machinability and moderate plasticity during cold deformation;
There is the first type of quenching brittleness in the range of 300-350 ℃ during heat treatment;
There is a tendency for white spots to form.
This type of steel is normally used in the quenched and tempered state.
When the carbon content is lower than the lower limit, it can also be used as carburized steel with high core strength.
In the medium-sized machinery manufacturing industry, it is mainly used to manufacture quenching and tempering parts with large cross-section and working under high-stress conditions, such as shafts, spindles and control wheels, screws, pins and gears under high loads;
In the chemical industry, it is used in the manufacture of welded parts, welded structures consisting of plates and tubes and high pressure tubes with a temperature not exceeding 250 ℃ working in a medium containing nitrogen and hydrogen;
It is used to manufacture fasteners below 450℃ and high pressure flanges and flange covers below 500℃ in the steam turbine and boiler manufacturing industry.
AISI 4130 is mainly applied in: in the medium-sized machinery manufacturing industry, it is mainly used to manufacture quenched and tempered parts with large cross-section and working under high stress conditions, such as shafts, spindles and operating wheels, screws, studs and gears under high loads.
AISI 4130 alloy steel contains chromium and molybdenum as reinforcing agents.
It has a low carbon content and is therefore easy to weld.
| Element | Composition |
|---|---|
| Carbon (C) | 0.28 – 0.33 |
| Silicon (Si) | 0.15 – 0.35 |
| Manganese (Mn) | 0.40 – 0.60 |
| Sulfur (S) | Allowable Residue ≤ 0.040 |
| Phosphorus (P) | Allowable Residual ≤ 0.035 |
| Chromium (Cr) | 0.80 – 1.10 |
| Nickel (Ni) | Allowable Residual ≤ 0.030 |
| Copper (Cu) | Allowable Residual ≤ 0.030 |
| Molybdenum (Mo) | 0.15 – 0.25 |
Mechanical Properties of 4130 Steel
| Mechanical property | Specification |
|---|---|
| Tensile strength (σb) (MPa) | ≥ 930 (95) |
| Yield strength (σs) (MPa) | ≥ 785 (80) |
| Elongation (δ5) (%) | ≥ 12 |
| Area Reduction (ψ) (%) | ≥ 50 |
| Akv Impact Energy (J) | ≥ 63 |
| Impact Resistance (αkv) (J/cm²) | ≥ 78 (8) |
| Hardness (HB) | ≤ 229 |
| Sample size | 25mm blank size |
| Heat Treatment Specification | Quenching at 880°C, cooling with water or oil; Quenching at 540°C, cooling with water or oil. |
What is the difference between 4140 steel and 4130 steel?
4140 is a grade of American steel, equivalent to China's 42CrMo alloy structural steel, and 4130 is a grade of American steel, equivalent to China's 30CrMo.
