Cast silico-manganese steel is a kind of common medium and low alloy high-strength cast steel. Because silico-manganese steel castings have better mechanical properties, silico-manganese steel castings are widely used in large-scale machinery and transportation equipment. Some kinds of gears, wheels, beams, train bolsters, side frames, and columns of hydraulic presses and other key load-bearing components in mechanical parts are made of silico-manganese steel castings.
The silicon element can play a solid solution strengthening effect on the ferrite in the cast steel, thereby improving the yield strength of the cast steel. In medium carbon manganese steel, the mass fraction of silicon element is about 1%. After quenching and tempering (Q+T) heat treatment, the strength of cast silico-manganese steel can be increased by 15%-20% while maintaining the toughness of steel castings without significant reduction. If the ratio of silicon and manganese is matched properly, the tendency of grain growth during heat treatment of silico-manganese steel can be slightly reduced.
Chemical Composition of Cast Silicon-Manganese Steel | |||||
Steel Grade | C (%) | Si (%) | Mn (%) | P (%) | S (%) |
ZG20SiMn | 0.12-0.22 | 0.60-0.80 | 1.00-1.30 | ≤0.035 | ≤0.035 |
ZG30SiMn | 0.25-0.35 | 0.60-0.80 | 1.10-1.40 | ≤0.04 | ≤0.04 |
ZG35SiMn | 0.30-0.40 | 0.60-0.80 | 1.10-1.40 | ≤0.04 | ≤0.04 |
ZG45SiMn | 0.40-0.48 | 1.10-1.40 | 1.10-1.40 | ≤0.04 | ≤0.04 |
ZG50SiMn | 0.46-0.54 | 0.85-1.15 | 0.85-1.15 | ≤0.04 | ≤0.04 |