40CrMnMo Steel Alloy Round Steel Bar

Technique Hot Rolled
Application Structural Steel Bar
Alloy Or Not Non-Alloy
Special Use Cold Heading Steel
Type Alloy Carbon Steel Bar
Tolerance ±1%
Processing Service Bending, Welding, Decoiling, Cutting, Punching
Delivery Time 15-21 days

40CrMnMo hot rolled steel round bars

After quenching and tempering, 40CrMnMo round steel has good comprehensive mechanical properties, good hardenability, and high tempering stability. Mostly used in quenched and tempered state. 40CrMnMo round steel is often used to manufacture heavy-duty, large cross-section gear shafts, gears, rear axle axles, shafts, eccentric shafts, connecting rods, and similar parts of steam turbines. It can also be used instead of 40CrNiMo round steel.



Chemical and Mechanical

Chemical composition (wt.%)
C(%) Si(%) Mn(%) Cr(%) Mo(%)
0.37-0.45 0.17-0.37 0.90-1.20 0.90-1.20 0.20-0.30


Mechanical Properties
Rp0.2 (MPa) Rm (MPa) Impact Elongation A Z (%) Delivery Hardness HB
KV (J) A (%)
823 (≥) 834 (≥) 41 33 12 Solution & Aging, Ann, Ausaging, Q+T 233


40CrMnMo has a wide range of applications in the fields of aviation, aerospace, machinery, and marine engineering. Specifically, it has a large number of applications in the key components of aircraft, aviation engines, etc. 40CrMnMo steel can also be used in the manufacture of automobile booms, machinery parts, vibration sieves, etc., which are mainly responsible for bearing pressure, shearing, tearing, bending, and other structures and parts that can withstand loads and stress.


Ⅰ. Classified by process

Round steel is divided into three types: hot rolled, forged and cold drawn. The specifications of hot-rolled round steel are 5.5-250 mm. Among them: 5.5-25 mm small round steel is mostly supplied in bundles of straight strips, which are often used as steel bars, bolts and various mechanical parts; round steel larger than 25 mm is mainly used for manufacturing mechanical parts and tube blanks of seamless steel pipes wait.


Ⅱ. Classification by chemical composition

Carbon steel can be divided into low carbon steel, medium carbon steel and high carbon steel according to chemical composition (that is, carbon content).

(1) Mild steel

Also known as mild steel, the carbon content is from 0.10% to 0.30%. Low carbon steel is easy to accept various processing such as forging, welding and cutting, and is often used to make chains, rivets, bolts, shafts, etc.

(2) Medium carbon steel

Carbon steel with a carbon content of 0.25% to 0.60%. There are killed steel, semi-killed steel, boiling steel and other products. In addition to carbon, it can also contain a small amount of manganese (0.70% to 1.20%). According to product quality, it is divided into ordinary carbon structural steel and high-quality carbon structural steel. Good thermal processing and cutting performance, poor welding performance. The strength and hardness are higher than low carbon steel, but the plasticity and toughness are lower than low carbon steel. Hot-rolled and cold-drawn materials can be used directly without heat treatment, or after heat treatment. Medium carbon steel after quenching and tempering has good comprehensive mechanical properties. The highest hardness that can be achieved is about HRC55 (HB538), and σb is 600-1100MPa. Therefore, in various uses of medium strength level, medium carbon steel is the most widely used. In addition to being used as building materials, it is also widely used in the manufacture of various mechanical parts.

(3) High carbon steel

Often called tool steel, the carbon content is from 0.60% to 1.70%, and it can be hardened and tempered. Hammers, crowbars, etc. are made of steel with a carbon content of 0.75%; cutting tools such as drills, taps, reamers, etc. are made of steel with a carbon content of 0.90% to 1.00%.


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