High-strength core rivets in the cold or hot and rolling thread after the use of salt bath furnace or roller furnace for quenching, tempering heat treatment to improve its strength and hardness. Heat treatment is an important process to determine the quality of high strength core pulling rivet products.

 

Quenching temperature is usually guaranteed at 800-9009C, the tempering temperature according to the different characteristics of steel, control in the 350-6501C. If you master the tempering temperature can reduce its impact on the hysteresis rupture strength, while ensuring the tensile strength of riveted products, to meet the design requirements. In order to ensure the uniformity of the heat treatment, it is necessary to select the steel with a small reduction in the middle hardness after the heat treatment.

 

The dew point in the furnace must be accurately adjusted in the heat treatment, and the surface decarburization of the heat-treated product is the main factor causing the variation of the riveting moment coefficient, and the re-carburization will increase the sensitivity of the hysteresis.