Residual stress refers to the unbalanced plastic deformation of materials in the process of deformation or casting production, or is introduced when they are machined, heat treated and welded. When rolling the plate, if the rolling diameter is small, the compressive residual stress will appear on the surface. If the roll diameter is large, such as flat calendering rolling, the tensile stress will appear on the surface and the compressive stress will appear on the center.
Aluminum plate manufacturer
轧制后板材沿厚度在轧制方向上表层残余着拉应力，内层金属残余着压应力，固溶处理时板材被加热到再结晶温度以上，轧制过程中所形成的残余内应力得以消 除。将加热后的板材快速放入冷水槽中或喷水淬火，此时由于表面金属冷 却得比内层的快，淬火初期表层金属剧冷、急剧收缩，基于板材的整体性，表层金属产生拉应力，内层金属产生压应力。
After rolling, the residual tensile stress in the surface layer and the residual compressive stress in the inner layer along the rolling direction of the thickness of the plate. During solution treatment, the plate is heated above the recrystallization temperature, and the residual internal stress formed in the rolling process is eliminated. When the heated plate is quickly put into a cold water bath or quenched by water spray, the surface metal cools faster than the inner metal, and the surface metal cools sharply and shrinks sharply at the initial stage of quenching. Based on the integrity of the plate, the surface metal produces tensile stress and the inner metal produces compressive stress.
With the further cooling of the plate
The results show that the residual compressive stress in the surface layer and the residual tensile stress in the inner layer are opposite to the residual internal stress in the rolling process. The magnitude of residual stress depends on material properties, shape and heat treatment conditions. In general, the higher the thermal conductivity, the smaller the coefficient of thermal expansion, the lower the modulus of elasticity and the strength at high temperature, the smaller the residual stress.
In addition, casting, welding and other processes will cause residual stress, improper assembly of parts will also cause residual stress, even aging treatment will also have residual stress, and cause small changes in size. In composite materials, due to different material properties, there are inevitably residual stress.