English
Zhongchi
Zhongchi
Zhongchi
Zhongchi
Zhongchi
Zhongchi
Zhongchi
Zhongchi
Zhongchi
G High-frequency quenching surface treatment.
Z Normalising
C (General) quenching, pulse quenching, isothermal quenching
T Tempering
H Flame (quenching)
S Carburising
D Nitriding
Secondly, the meanings of the above symbols all include subsequent heat treatment as specified in the heat treatment specifications; for example, some may require quenching and tempering. As for preliminary heat treatment, this should be determined in accordance with the relevant specifications based on other requirements for the component.
Thirdly, the numbers following the symbols represent the final hardness values achieved; two-digit numbers represent HRC values, three-digit numbers generally represent HB values, and in the case of nitriding, they represent HV values.
Furthermore, in some cases, the heat treatment or hardness zone must be indicated on the drawing.
Finally, the numerical values representing hardness generally indicate a range of plus or minus 5 units for HRC (with the minimum value indicated when the number approaches 60), plus or minus 30 units for HB, and the minimum value for nitriding. For example:
G48: The number 48 precisely represents HRC 46–51
T235: The number 235 precisely represents HB 220–250
C42: The number 42 precisely represents HRC 40–45
C35: The number 35 precisely represents HRC 32–38
T235 refers to quenching and tempering, with a hardness of HB 235;
T235 refers to quenching and tempering, with a hardness range of HB 220–250 or HRC 22–25 after tempering;
C42 and C35 refer to quenching, with hardnesses of HRC 42 and 35 respectively;
G48 refers to high-frequency quenching with a hardness of HRC 48
