24 July 2021 Structural Steel Bar
30Cr Structural Steel Bar
30Cr is a Chinese standard alloy structural steel specified in GB/T 3077-1999 . It has high strength and high hardenability. The critical hardening diameter in oil is 8～34mm, and it is critically hardened in water. The penetration diameter is 19～56mm. However, the cold deformation plasticity and weldability of 30Cr structural steel are moderate, and the machinability of annealing or high temperature tempering is good. 30Cr steel can be used to make parts with better internal toughness and harder surface, generally used to make parts with higher toughness and hardness. 30Cr steel is usually used in quenched and tempered state, and can also be used after normalizing. It is used to manufacture important parts such as shafts, small shafts, balance levers, shake Rods, connecting rods, bolts, nuts, gears and various rollers, etc. In addition, this kind of steel can also be used as high-frequency surface hardening steel for the production of parts that require high surface hardness and wear resistance.
Chemical Composition:
| C(％) | Si(％) | Mn(％) | P(％) | S(％) | Cr(％) | Ni(％) | Cu(％) |
|---|---|---|---|---|---|---|---|
| 0.27～0.34 | 0.17 ~ 0.37 | 0.50 ~ 0.80 | ≤ 0.035 | ≤ 0.035 | 0.80～1.10 | ≤ 0.030 | ≤ 0.030 |
Mechanical Propoerties:
| Yield Strength Rp0.2(MPa) | Tensile Strength Rm(MPa) | Elongation δ5 (%): | Section shrinkage ψ (%): | Impact energy Akv (J): | Impact toughness value αkv (J/cm2) | Hardness |
|---|---|---|---|---|---|---|
| ≥ 685 (70) | ≥ 885 (90) | ≥ 11 | ≥ 45 | ≥ 47 | ≥ 59(6) | ≤ 187 HB |
Heat treatment:
- The first quenching heating temperature (℃): 860; coolant: oil
- Second quenching heating temperature (℃): -Tempering heating temperature (℃): 500; Coolant: water, oil
Equivalent Grade:
American grade: ASTM 5130
Japanese grade: JIS SCR430