Investigation On Property Of 16Mn Steel Welded Joint Made By Double Wire Submerged Arc Welding Process

Two-wire submerged arc welding has many characteristics like high efficiency, high mechanization, high quality welding and so on. So it has been used in production, but the research is still relatively few on its theory. The investigation is focused on welding process parameters how to impacting on the metal property of two-wire submerged arc welded joints in present paper. The experimental basis for the practical production and the reference for studying further the joint properties of two-wire submerged arc welding is provided by present investigation.The analysis of three-dimensional finite element analysis of transient temperature field is carried on the 16Mn steel double-wire submerged-arc welding by ANSYS software in present paper. The simulation and analysis of weld thermal cycle curve are simulated and analysized, the experiment quantity is reduced and the welding procedure parameters is optimized, moreover, the welding quality is improved to provide the theory instruction for the welding tests. Respectively welding experiments is conducted at different welding current, welding speed and wire spacing conditions by double wire submerged arc welding process on the 20mm thick 16Mn steel. The tensile tests of these welded joints are performed, and cross-section shape and metal microstructure of these welded joints are analysed and hardness of these welded joints is determined .The results obtained are as following.(1) Keeping other welding parameters constant, with the increase of the welding current and the wire spacing, the aspect ratio of weld is increased, but with the increase of welding speed, the aspect ratio of weld is reduced gradually.(2) With the increase of the welding current,the metal microstructure of welded joints is more and more coarse, hoterogeneity of microstructure is increased, and hardness curves of joints change more and more obviously, and the elongation and yield strength of welded joints are increased correspondingly, but the current is over large or small will cause the tensile strength of joints to reduce. By comparison, when welding current of the front wire is 700A and welding current of the rear wire is 600A , mechanical property of the welded joint is better.(3) If welding speed is over big, the metal microstructure of the welded joints is more complex; hardness peak of the welded joints appears in the heat affected zone, and hardness of the welded joints is increased with the increasing of welding speed; when welding speed of 0.0050m / s, fracture location is in the base metal,the mechanical property of the joint is better.(4) With the increase of wire spacing, the metal microstructure grain size of welded joints is slightly decreased; the different wire spacing microhardness peak of welded joints all appears in heat affected zone; the tensile strength of three group welded joints are higher than that of the base metal, so the fracture occurs in the base metal zone.