Research On PAW Seam Performance And Formation Mechanism Of Marine Stainless Steel

Stainless steel materials have been widely used in modern shipbuilding industry owing to their excellent corrosion resistance,satisfactory mechanical strength and good toughness.The PAW(Plasma-Arc Welding)uses plasma arc as a heat source which has the advantages of high energy density,fast welding speed,no need of welding wire and good weld quality.If the plasma arc welding could be applied to the welding of marine stainless steel,it will increase the welding speed,reduce the costs,and increase profits of the shipyard.In this paper,we use 304 stainless steel to carry out the experiment to study the characteristics of the stainless steel perforated plasma arc welding process.Through several tests,it is found that the weld forming is mainly affected by the welding speed.The weld penetration is mainly affected by the welding current,the tungsten internal shrinkage and the distance from the welding torch.In this paper,the orthogonal test of five factors and three levels is designed to study the influence of welding speed,welding current,plasma flow rate,tungsten internal shrinkage and welding distance from the workpiece distance on welding quality.The purpose of this paper is to analyze the forming mechanism of stainless steel perforated plasma arc welding and observe the weld shape and test the mechanical properties of the weld.Through the plasma soldering experiments,we got the best parameters of the experiment,the torch distance is 2mm,the welding speed is 7.7cm / min,the current is 100 A,the tungsten inner shrinkage is 2mm.The welds were subjected to wire cutting,tensile test and metallographic test.The shape and microstructure of the joint were observed and the mechanical properties of the weld were analyzed.The results show that the mechanical properties of the welding seam are almost the same as those of the flat welding weld,which is more than 90% of the mechanical properties of the base metal.We get the mechanical properties roughly as follows,after stretching fracture,the maximum force of 62886.9N,extension strength of 875 N / mm2.The ultimate tensile stress is 855.59 mp.However,the effective penetration of the riser weld is higher than that of the flat weld,and the flat weld can only reach 8mm,but the welding seam of the riser weld can reach at least 20 mm.