1)The material for U-joint cross is 20Cr or 20CrMnTi alloy steel(hardness after heat treatment is HRC 58 -63 degree) 2)The material for bearing caps is 20Cr or 20CrMnTi alloy steel(hardness after heat treatment is HRC 58 -63 degree); 3)The material for needle roller is GCr15(hardness after heat treatment is HRC 59 -63 degree); 4)The material for circlip is 65Mn; 5)Cementite deepness: 0.8-1.3mm