The manual argon tungsten-arc welding was used to weld TC4 titanium alloy plate (150 mm X 150 mm) of different thickness(25 mm / 18 mm).The stress relief annealing and isothermal annealing were implemented on the plate , the status of which was compared with that of natural cooling (without heat treatment) sample.The effect of different heat treatment process on microstructure and mechanical properties of weld area was analyzed.The results show that microstructure of weld area without heat treatment and the stress relief annealing are martensite and a rough acicular martensite ,respectively.After isothermal annealing (930 ℃/2 h+530 ℃/4 h), the microstructure are mainly acicular martensite at root and top of the weld area, with martensite + slice α phase at the central weld area, while the Vickers hardness of the weld area is 434 HV.The tensile strength of alloy was increased by the lower content of Al element after isothermal annealing.Tensile strength is 904 MPa , the elongation is 8.0%,and the tensile fracture in the region of the base metal belongs to the ductile fracture.%采用手工钨极氩弧焊焊接不同厚度(25 mm/18 mm)TC4钛合金板(150 mm×150 mm),对其分别进行去应力退火(600 ℃/4 h)、等温退火(930 ℃/2 h+530 ℃/4 h)并与未热处理(自然冷却)态进行比较,分析不同热处理工艺对焊缝的组织和力学性能的影响.结果表明,未热处理态焊缝区组织为马氏体,去应力退火后组织为较粗大的针状马氏体,等温退火(930 ℃/2 h+530 ℃/4 h)焊缝根部和顶部组织主要为针状马氏体,中部组织则为马氏体+片状α相,此时焊缝的维氏硬度为434 HV.由于等温退火后Al含量降低使合金抗拉强度增大,抗拉强度为904 MPa,伸长率为8.0%,拉伸断口在母材区域,属于韧性断裂.
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