30CrMo steel and 35CrMo steel in special steel are very similar, but there are also essential differences.
1. Chromium-molybdenum alloy steel is different
30CrMo chromium-molybdenum alloy steel, the mass fraction of carbon is about 0.30%. 35CrMo chromium-molybdenum alloy steel, the mass fraction of carbon is about 0.35%. From the perspective of the composition of chromium-molybdenum alloy steel, 35CrMo steel has a higher carbon content than 30CrMo steel. Therefore, 35CrMosteelis superior to the two materials in terms of hardness, tensile strength and yield after heat treatment. But on the contrary, 30CrMosteelis better in terms of toughness.
2. Different characteristics
30CrMo steel has good thermal strength, high strength and toughness, and high hardenability. The critical hardening diameter in oil is 15-70mm, and it has sufficient high temperature strength below 500°C, but its strength at 550°C decreases significantly. 30CrMo steel has the first type of temper brittleness in the range of 300-350℃ during heat treatment, and has a tendency to form white spots.
35CrMo steel has high static strength, impact toughness and high fatigue strength, good hardenability, no overheating tendency, small quenching deformation, good plasticity during cold deformation, proper preheating before welding is required during welding, and slow after welding process measures such as cold to control the welding line energy. 35CrMo alloy structural steel also has high static strength, impact toughness and higher fatigue limit, higher hardenability than 40cr, high creep strength and endurance strength at high temperature, and long-term working temperature can reach 500℃.
