The Chemical Composition of AISI 4145H contains a medium level of the carbon content of 0.42-0.49 %. The material has an Mn content of 0.65-1.10 % which imparts hardness to the material. The contents of P is reduced to 0.035% and S is reduced to 0.040 % max as excess content of P and S can damage the quality of steel and can cause the alloys steel to break at low stresses. The SAE 4145H has Ni and Mo content along with Cu.