Existing batch of screws, originally scheduled to be made of 35 steel, the requirements of its head after heat treatment hardness of 35 ~ 40 HRC. now the material is mixed in the T10 steel and 10 steel If still according to 35 steel heat treatment (see your hardness range belongs to the tempering treatment), not can meet the requirements, 10 steel hardness is not enough, T10 steel is too hard,

35 steel is a high-quality carbon tempered steel, its normal tempering quenching and heating temperature is 840 ~ 850 ℃, tempering 580 ~ 600 ℃

10 steel belongs to the low carbon steel, used for stamping or carburizing treatment! Because of the low carbon content, heating to 840 ~ 850 ℃ has not entered the complete austenite zone, belongs to the incomplete austenitization, therefore, after quenching, one is because of the lack of complete austenitization, and the second is the carbon content is low, so get the amount of martensite is very small, the hardness basically does not occur a big change, and then tempered at high temperatures, the final hardness is insufficient to completely fail to meet the requirements.

T10 steel belongs to high-quality carbon tool steel, high carbon content, its heating temperature is 770 ~ 790, if it is heated to 840 ~ 850 ℃ quenching, hardness of up to 58 ~ 62HRC, even after tempering at high temperatures, due to carbide precipitation hardness is also very high, the final hardness index is not up to the requirements.