The Research Of The310S Austenitic Heat Resistant Stainless Steel TIG Welding And Joint Performance

310S austenitic heat-resistant stainless steel is widely used in the manufacture of allkinds of high temperature anti-oxidation parts. Generally it has a single organization of theaustenitic at the room temperature, it can obtain the continuous full welded joint moreeasily, but some defects happen easily in the actual welding process such as the hot crack,the chromium carbide precipitation, the joint embrittlement. Meanwhile we should alsoconsider the tendency of crack, the resistance of intergranular corrosion, the strength in thehigh temperature and the resistance of the oxidation. It is necessary to study the evolutionlaw of the joint microstructure when the austenitic heat resistant stainless steel under thedifferent welding process, it is the key problem to promote the austenitic heat resistantstainless steel weldments widely used.Using the TIG welding method, conduct the weld test of310S austeniticheat-resistant stainless steel. The welding technology,s influence in the welding jointmicrostructure and mechanical properties are researched. The distribution of residualstress of welded joint is measured by the method of X ray. The new distribution of residualstress is analyzed and compared after the different stress relieving process. The weldedjoint fatigue performance is tested. The fatigue property of weldment in different survivalconditions are studied. The main research contents and conclusions are as follows:(1) By analyzing the welding joint microstructure and mechanical properties, the bestwelding process parameters is: the welding current I is140A, the welding speed Vh is0.32m/min, the wire feeding speed Vs is0.32m/min.(2) The evolution law of the welding joint microstructure is analyzed based on theSchaeffler diagram, the solidification mode of the stainless steel weld metal is: L?L+???.(3) The form distribution of the longitudinal residual stress is not completelysymmetric distribution on the direction of perpendicular to the weld, the very centre of theweld position x=0is the symmetry center, the stress state is compressive in the negativedirection of the x area, there are maximum compressive stress60MPa in the straight liney=-35; the stress state is tensile in the positive direction of the x area, there aremaximum tensile stress207MPa in the straight line y=35; The form distribution of thethe transverse residual stress is not completely symmetric distribution on the direction ofParallel to the weld; the very centre of the weld position x=0is the symmetry center; there are maximum tensile stress184MPa in the straight line y=0and there aremaximum tensile stress248MPa in the straight line y=35.(4) The best heat treatment process scheme to eliminate the welding residual stress is:heating the welding parts with the furnace temperature to600?, preserving heat1.5h,then cooling the parts with the slow cooling furnace to below300?then removing it.With the increase of holding time, the effect of residual stress is more obvious.(5) When conducting the tension-tension fatigue practicality tests the welding jointfracture in the weld under the condition of the stress ratio R=0.1,0.4; Under thecondition of survival rate P=50%, the fatigue strength of welded joint is83MPa when R=0.1, the fatigue strength of welded joint is75MPa when R=0.4. Under the condition ofP=95%, the fatigue strength of welded joint is75MPa when R=0.1, the fatigue strengthof welded joint is70MPa when R=0.4.(6) With the increase of stress ratio the fatigue strength of the weldments has thetrend of lower under the condition of the same survival rate, the higher survival rate s-ncurve has a relatively low fatigue strength under the condition of the same stress ratio.