Effect of quenching conditions on localized residual stresses

Conclusions

• 1. It was shown that with decreasing precooling temperatures (before quenching) the residual surface compression stresses decrease in samples of 18KhNVA steel 70 mm in diameter, and become tensile stresses when the precooling temperature is below 600°C. At a depth of 10–12 mm the tensile stresses decrease but do not change sign.

• 2. An increase in the temperature at which quenching is interrupted has the same effect. This indicates that slow cooling (in air) in the temperature range in which martensite is formed decreases the thermal stresses much more than the structural stresses.

• 3. Both quenching methods (precooling and interrupted quenching) decrease the stress gradient in the surface and subsurface layers. The combination of precooling and interrupted quenching has an additive effect on the decrease of the stress.