The Stress Corrosion Properties Study Of 304 Stainless Steel TIG Welded Joints

Since the end of the nineteenth century,there have been a great deal of studies on corrosion problems under stress,however,it is still difficult to explain the relationship between stress and corrosion processes because of the complexity of the interaction.As one of the stainless steel processing methods,welding is of great significance for the use of austenitic stainless steel workpieces.In the welding process,weld and its vicinity undergoes,have welding residual stress at the,which will easily lead to corrosion damage of the stainless steel in the electrolyte solution.However,relevant design work and safety assessment still lack sufficient basic reference data.In this paper,It is used to weld 304 stainless steel by pulsed tungsten argon arc welding.For the welded joints under different welding processes,metallographic,mechanical tests,residual stress tests and slow stress strain tensile tests were carried out.This paper attempts to explain the influence of welding process on stress corrosion sensitivity by welding residual stress.The main research results are as follows:1?With the reduction of welding heat input,the microstructure of the weld zone is refined,the ferrite is dendritic and regular in the grain boundary,and the tensile strength and elongation after fracture increase,but the welding line When the energy is in two extreme conditions,the performance of the welded joint changes inversely,such as the V18I100/150 group with the lowest heat input,and the mechanical properties are reduced.2?As the welding heat input decreases,the measured welding residual stress has a tendency to decrease,while the residual stress in the same set of parameters is:heat affected zone>weld>base metal;From the measured results of residual stress,a local maximum stress zone appears near the weld line,which explains that there is a Vickers hardness peak.It can be preliminarily judged that such welded joints have two hardness peaks,one in the weld and one near the weld line.The residual stress distribution of the V18I100/200 welded joints was simulated by ABAQUS.The calculated values of the calculated values and the test values in the heat affected zone are consistent.The calculation result is small because it neglects factors such as work hardening.3?As the heat input increases,corrosion begins to occur in areas where stress is concentrated near the weld line.However,it is not obvious because the compression residual stress concentration at the fracture inhibits crack growth.During the stress corrosion process,pitting corrosion occurs in the local stress concentration area at the edge of the weld,where the residual stress perpendicular to the weld direction is the compressive stress,which hinders the pitting corrosion from proceeding.Combined with the trend of residual stress distribution,the crack growth rate outside the corrosion fracture negatively correlated with the compression residual stress.