Strength and hardening of high performance, after quenching and low temperature tempering, can get good comprehensive mechanical properties and low temperature impact toughness, no temper brittleness and should therefore be of secondary quenching to improve toughness in the center, unfavorable cooling quenching, cold deformation plastic high, cold drawing, the high temperature normalizing and tempering, good processability, good weldability. Welding should generally be preheated to 100 to 150 DEG C, and is generally regarded as penetration of carbon steel