Investigation on the effect of cryogenic treatment on initial residual stress and reduction mechanism of hydrogen-resistant steel

Hydrogen-resistant steel thin-walled components are widely used in various fields due to their advantages of high strength and toughness. The residual stress inside the material is a key factor affecting the deformation of hydrogen-resistant steel thin-walled parts. This article uses orthogonal experimental method and contour method to study the effects of deep cooling temperature, deep cooling time, number of cold and hot cycles, and deep cooling cooling rate on residual stress inside hydrogen steel. The results indicate that extending the cryogenic treatment time, increasing the number of cryogenic treatments, and reducing the cooling rate can reduce the initial residual stress of hydrogen-resistant steel. Compared with untreated, this method can reduce the initial residual stress by 77.5%. In addition, it was found through EBSD and TEM testing after cryogenic treatment that the grain size of the sample can be refined and the dislocation density can be reduced, thereby changing the initial residual stress. Ultrasonic vibration aging treatment on the basis of cryogenic treatment can further reduce the initial residual stress, with a reduction rate of 25.1%.