Both 4340 and 4140 are relatively common steel grades. We also supply 4340 steel and 4140 steel to a large number of customers around the world. These two grade steels differ in chemical composition, performance, and application fields. Below is a chemical and mechanical properties comparison of AISI 4340 vs 4140 steel.
4340
4340 Steel is a high quality Quenched and Tempered Alloy Structural steel, It belongs to the high quality medium carbon, Oil Quenched & Tempered Hardness is 28-34 HRC.4340 Annealing delivery hardness less than 250HB.
4140
AISI/SAE 4140 grade is a versatile alloy with good atmospheric corrosion resistance and reasonable strength. It shows good overall combinations of strength, toughness, wear resistance and fatigue strength.
Chemical Composition Comparison: 4340 vs 4140 steel
| grade | C | Mn | P | S | Si | Cr | Mo | Ni |
| 4340 | 0.38-0.43 | 0.60-0.80 | ≤0.035 | ≤0.035 | ≤0.040 | 0.70-0.90 | 0.20-0.30 | 1.65-2.00 |
| 4140 | 0.25-0.38 | 0.60-0.90 | ≤0.035 | ≤0.035 | ≤0.040 | 0.90～1.20 | 0.15-0.30 |
Application Comparison: 4340 vs 4140 steel
4340
ASTM 4340 steel is an alloy structural steel, 4340 is used for engineering structural, Used as require good toughness, high strength, as well as the important conditioning of large size, heavy machinery such as high load of axial, turbine shaft, larger than 250 mm in diameter of helicopter rotor shaft, turbojet engine turbine shaft, blade, high load of transmission parts, fasteners of the crankshaft. Gear, etc
4140
4140 alloy steel finds many applications as forgings for the aerospace and oil and gas industries, along with myriad uses in the automotive, agricultural and defense industries, Typical uses are forged gears and shafts, spindles, fixtures, jigs, and collars.
OTAI SPECIAL STEEL is ASTM 4340 and 4140 Alloy steel stockholders and suppliers from China. we have more 16 years experience in 4340/4140 steel round bar, plate, steel flat bar, square supply.
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