A-TIG Welding Technology Of Titanium Alloy Applied Research

Titanium as a kind of excellent functional material, has for the density is small, than the intensity is high, the high and low temperature resistance and erosion resistance is good, and many other features. But titanium affinity at room temperature is bigger, so in the welding process of titanium alloy, the brittle weld easily happened; Had a great influence on comprehensive mechanics performance of weld. At present, in the process of the welding of titanium and its alloys, the most commonly used for tungsten argon arc welding.Compared to conventional TIG welding,A-TIG welding as an emerging technology, the electric arc is more concentrated, the penetration forcein creased more significantly and theheat input and stress reduced more significantly. A-TIG welding is widely used in the aerospace, automotive, pressure vessels, biotechnology, especially in the field of nuclear power in recent years due to that it can open groove welds on both sides, leaving no gaps, a single pass weld penetration welds or welding can reduce the number of layers significantly, which result in hieher productivity.The article through the orthogonal experiment contrast two kinds of TIG welding method and A- TIG welding under the condition of the same welding parameters. By changing the welding process parameters for butt welding of the titanium plates of different thickness, through stretch bending test, metallographic test, microhardness test and analysis of weld organization and the change of the performance, get the following results.(1) Under the same external conditions, When welding 2 mm titanium plate, the TIG weld needs 60 A current, while it only need 45 A current using A- TIG welding method.(2) The appropriate weld joint can be obtained by A- TIG welding welding with 100 A current, but it does not work when using the TIG weld method under the same external conditions.(3) The optimum technology parameters of 5mm TC4: voltage is 11 V, the welding current is 200 A, the welding speed of 40 mm / min, argon flow rate of 241 / min, the tensile strength of the joint is 914.935 MPa, the parent can be achieved 93.4% material; elongation of 1.67%. The optimum technology parameters of 6mm TC4: voltage is 12 v, welding current is 210 A, the welding speed is 3 m/h, the argon gas flow 28 l/min, the joint tensile strength is 965.714 MPa, can reach 98.6% of the parent metal; Elongation is 2.51%.(4) Through analyzing the sample section observation, two methods of welding welding stretch bending specimen fracture and deformation conditions are similar, most of the sample of the cracking position in the weld fusion line position and close to the heat affected zone, in the strength and toughness of weld heat affected zone of organization are smaller than the parent metal, A- TIG weld tensile strength under the condition of the same heat input is higher; Two methods of welding of the titanium alloy weld microstructure characteristics is mainly composed of acicular or knitting basket mesh alpha martensite, but there are some differences. Of the group size of tensile fracture in measurement, the contrast A- TIG welding TIG weld martensite acicular structure to small.