Effect of Thermal Refining on Mechanical Properties of Annealed SAE 4130 by Multilayer GTAW

摘要

During the first welding process in manufacturing a precise seam container,the steel material must first undergo a full annealing treatment.Multilayer welding operations are conducted and then applied with refining treatment to obtain the goal by hardening.The influence of thermal refining on mechanical properties of annealed SAE 4130 by multilayer GTAW (gas tungsten arc welding) was discussed.The AW (annealing+welding) and AWST (annealing+welding+solution+tempering) occurred with a minimum hardness value at GGHAZ (grain growth heat affected zone) due to coarse grain growth;the hardness occurred with sudden drops between the multilayer welding,but was still larger than the minimum value at HAZ (heat affected zone).The welded joint efficiency of the AWST was 89.9%,with the elongation reduced to 77.2% of AST (annealing+solution+tempering).The cross section of the tensile samples both appeared with a uniform dimple-shaped structure,and however the necking for AST was greater than that for AWST.The impact value for AWST was 166.5% of AST.Moreover,from microstructure observations,it was found that AWST had a greater tendency to ductile failure than AST.These results can be inferred:the process of steady pressure and the initial position of the precision tube breakage HAZ.However,when stress occurs instantly,HAZ can absorb more energy,therefore the initial damage does not occur.