Research On Welding Procedure Of A New Type Of Titanium Alloy Ti75

There are lots of applications of titanium alloy in national defence industry andcivil industry due to its excellent comprehensive performances and good weldabilities. As the development of industrial technology, the kinds of titanium alloybecome more and their applications are wider, so more technology problems aboutthe welding of new kinds of titanium alloy are proposed.Ti75is the new type of alpha titanium alloy developed by China ShipbuildingIndustry Corporation, mainly used in the deep-sea submarine manufacturing fields.The components and contents of elements in Ti75are close to TA12in nationalstandard, but its intensity is lower and ductility is higher. As a new type alloy withthe780MPa strength,101J·cm^-2impact toughness and260microhardness, there hasno research paper or academic paper related to Ti75welding technology. The mainpurpose of this paper is to form a systematic study about Ti75welding technology.The technological study contents welding parameter optimization, analysis ofmechanical properties, organizational analysis, and fracture analysis. Through aseries of welding experiments and analytical tests, this paper gains thoseconclusions as follows:Debugging and optimizing the welding parameters of manual TIG welding, weobtain beads without any defects, the forming seems good, the beads have excellentcomprehensive mechanical properties, there impact toughness and strength pass thebase metal level, although the bending property needs to be improved. All theresults provide conferences for narrow-gap TIG welding in choosing weldingparameters and analyzing the welding results. Conducting the welding experimentsunder eight heatinput levels, analyzing the mechanical properties andmicrostructures, we find that, as the increasing of heatinput, the width of HAZ, thesize of martensite in welding zone also increase and the eliminated martensites ininterlamination become more and obvious. The tensile strength and impacttoughness of HAZ increase, the impact toughness of welding zone and the bendingproperty of the beads go up first and then come down. When the welding heat aresetted at15.18KJ.cm^-1,16.56KJ.cm^-1,17.25KJ.cm^-1, the comprehensive mechanicalproperties are satisfactory. When weld the plates with16mm,22mm and42mm thickness, setting the prestressing angle at9°-11°,12°-14°,20°, we can gain beadswithout angular distortion or little distortion. Conducting after welding heattreatment to eliminate residual stress, the tensile strength decreases10.87%, but theimpact toughness and bending property have been greatly increased. The tensilestrength of42mm narroew-gap TIG welding beads exceed the base metal, theimpact toughness in HAZ and welding zone reach to65.27%,92.31%of the basemetal, the bending property in0-10mm and30-40mm are common, but the bendingproperty of10-30mm are excellent.Optiming the welding parameters of narrow-gap TIG welding in42mm andimproving the bending deformation ability are the main direction of our research infuture time.