Study on Welding Temperature and Joints Microstructure of TC4 Titanium Alloy Thin Plate in Laser Weld

Temperature and microstructure of laser welded joints of TC4 titanium alloy thin plate were studied.The results show that the closer to the weld center,the higher the peak temperatures of characteristic points,and the faster the heating rates and the cooling rates.The macromorphology of weld seam obtained from experimental is cone.Acicular martensite α′ forms basketweave microstructure in fusion zone.The basketweave microstructure has different dimensions in different grains.The microstructure of HAZ consists of original α,original β and tiny acicular martensite α′.From base metal zone to fusion zone,the dimensions of original α grains in HAZ increase firstly,and then decrease,disappear,while the dimensions of acicular martensite in HAZ increase continuously.