35CrMnSiA is a low-alloy ultra-high-strength steel. After heat treatment, it has good comprehensive mechanical properties, high strength, sufficient toughness, hardenability, weldability (preheating before welding), and processing formability, but it has good corrosion resistance and Low oxidation resistance, generally used after low temperature tempering or austempering. High-strength quenched and tempered structural steel. It has high strength and toughness, high hardenability, medium cold deformation plasticity, and good cutting performance. There is a tendency to temper brittleness, and the transverse impact toughness is poor. The welding performance is better, but when the thickness is greater than 3mm, it should be preheated to 150℃ first, and heat treatment is required after welding. Generally used after tempering.