GB 65Mn steel
65Mn steel is a Chinese GB standard spring steel, manganese (Mn) improves hardenability, so the strength, hardness, elasticity and hardenability are higher than that of 65# steel, but it has overheat sensitivity and quenching brittleness. Water quenching tends to form cracks. The annealed state has good machinability, low cold deformation plasticity and poor weldability.
65Mn high carbon steel is mainly used in the manufacture of various small-section flat springs, round springs, watchmaking mechanisms, etc. It can also be used to manufacture spring rings, valve springs, shock absorbers, clutch vanes and brake springs.
65Mn technical sheet
Below is the material data sheet of AISI 65Mn spring steel, including chemical composition, properties and heat treatment, etc.
Chemical composition
The table below lists the chemical composition of 65Mn high carbon steel based on thermal analysis.
| Chemical composition, % | |||||||||
| Standard | Note | W | Yes | Mn | P, ≤ | S, ≤ | Cr, ≤ | Ni, ≤ | Cu, ≤ |
| GB/T 1222 | 65 minutes | 0.62-0.70 | 0.17-0.37 | 0.90-1.20 | 0.030 | 0.030 | 0.25 | 0.35 | 0.25 |
65Mn Material Properties
Density: 7.85 g/cm3
| Mechanical properties | ||||||
| Standard | Note | Tensile strength, MPa, ≥ | Yield strength, MPa, ≥ | Elongation, %, ≥ | Reduction in area, %, ≥ | Brinell hardness, HBW, ≤ |
| GB/T 1222 | 65 minutes | 980 | 785 | 8.0 | 30 | 302 |
Notes: Bars with a diameter and lateral length not exceeding 80 mm and flat steel with a thickness not exceeding 40 mm.
Heat Treatment Specification
| Heat treatment | ||||
| Standard | Note | Quenching temperature, °C | Quenching medium | Quenching temperature, °C |
| GB/T 1222 | 65 minutes | 830±20 | Oil | 540±20 |
Annealing process: Annealing temperature (860 ± 10) °C, heat preservation for 45-60min, furnace cooling to (750 ± 10) °C, heat preservation for 3-3.5h and furnace cooling to 650 -660°C, then cooling outside the oven or slow cooling in a heat preservation well.
Equivalence of 65Mn spring steel
65Mn steel is considered equivalent to AISI SAE 1065, and some people also compare 65Mn with AISI/SAE 1075, 1095, 5160; JIS SK5 (SK85) and Chinese 8Cr13Mov, so the table below lists the chemical composition difference for your reference.
65Mn vs 1065, 1075, 1095, 5160, SK5 and 8Cr13Mov in chemical composition
| Chemical composition % | ||||||||||
| Note | W | Yes | Mn | P(≤) | S (≤) | Cr | Ni (≤) | Cu (≤) | Mo | V |
| 65 minutes | 0.62-0.70 | 0.17-0.37 | 0.90-1.20 | 0.030 | 0.030 | ≤ 0.25 | 0.35 | 0.25 | – | – |
| 1065 | 0.60-0.70 | 0.60-0.90 | 0.040 | 0.050 | – | – | (0.20) | – | – | |
| 1075 | 0.70-0.80 | 0.40-0.70 | 0.040 | 0.050 | – | – | (0.20) | – | – | |
| 1095 | 0.90-1.03 | 0.30-0.50 | 0.040 | 0.050 | – | – | (0.20) | – | – | |
| 5160 | 0.56-0.61 | 0.15-0.35 | 0.75-1.00 | 0.035 | 0.040 | 0.70-0.90 | – | (0.30) | – | – |
| SK5 | 0.80-0.90 | 0.10-0.35 | 0.10-0.50 | 0.030 | 0.030 | 0:30 | 0.25 | 0.25 | – | – |
| 8Cr13Mov | 0.70-0.80 | 1.00 | 1.00 | 0.040 | 0.030 | 1:00pm-2:50pm | 0.60 | 0.10-0.30 | 0.10-0.25 | |
