The material of 20# seamless steel pipe is 20# steel, the strength is slightly higher than 15#, it is rarely quenched and has no temper brittleness. Cold deformation has high plasticity and is generally used for bending, rolling, flange and hammer arching. The welding performance of arc welding and contact welding is good, the thickness is small during gas welding, and cracks are easy to occur on parts with strict requirements or complex shapes. The machinability cold drawn or normalized state is better than the annealed state, and is generally used to manufacture workpieces with low stress and high toughness requirements.