| Dissimilar stainless steel welding structure has good comprehensive properties,can work normally in complex and changeable harsh service environment,and has been widely used in equipment manufacturing field of nuclear power equipment,navigation and aerospace,petrochemical industry,electronic equipment and pressure vessel.During laser welding of dissimilar stainless steel,the chemical composition and metallurgical structure of the welding zone are changed by transient high temperature,and complex non-uniform stress field is produced in the adjacent area of welded joint.It not only changes the mechanical properties of welded joints of dissimilar stainless steel,but also directly influences the fatigue strength of welded structures.Therefore,the research on fatigue behavior of welded structure of dissimilar stainless steel not only has practical application value,but also can provide a theoretical basis for anti-fatigue design and service safety performance of welded structure of dissimilar stainless steel.In view of this,the fatigue behavior of dissimilar stainless steel welded structure is analysed by means of experiment and simulation.The main contents are as follows:First,the laser welding process of dissimilar stainless steel was studied.According to the orthogonal test method,the laser welding experiment of dissimilar stainless steel was designed,and the laser welding test piece of 1mm SUS304L/SUS316 dissimilar stainless steel was prepared,and the laser welding experiment of dissimilar stainless steel was carried out.The range analysis method and fuzzy comprehensive evaluation method were used to optimize the welding process parameters.Second,the welding residual stress of dissimilar stainless steel and its influence on fatigue properties are analyzed.The welding residual stress simulation scheme is designed according to the laser welding process test,and the laser welding program is compiled by ANSYS APDL.The welding process temperature and residual stress are simulated and analyzed,based on which the fatigue load curve of welding structure is constructed.The load curve and simulation model are imported into Fe-safe software to calculate the fatigue life of dissimilar stainless steel welded structure.Third,the impact of notch shape on fatigue properties of welded structures is analyzed.Tensile tests and low-cycle fatigue tests of dissimilar stainless steel welded structures were carried out.The H specimens were tested by Origin data processing software.The stress-life(S-N)and strain-life(-N)curves of V-notch specimens and Y-notch specimens were fitted,and the low-cycle fatigue life of dissimilar stainless steel welded specimens was calculated by Matlab software. |
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