Ti-23Al-17Nb alloy is an important high temperature structural material used in the space and aerospace fields. Welding of this alloy is an indispensable processing method, so the microstructures and mechanical proper...Ti-23Al-17Nb alloy is an important high temperature structural material used in the space and aerospace fields. Welding of this alloy is an indispensable processing method, so the microstructures and mechanical properties of these welded joints must be studied to improve the welds. Longitudinal three-point bending tests were conducted to measure the bending ductility of laser beam welded joints. The crack distribution and fracture surface were investigated to further analyze the fracture behavior. The results indicate that the bending ductility decreases as the heat input by the laser beam welding increases. The crack inducing strain reaches 4.24%, while the fracturing strain exceeds 5% when the heat input is below 316 J/cm. If the columnar crystal grain of the weld metal exhibits a uniform orientation, the bending ductility is worse. The fractography analysis shows that the cracking propagates transgranularly and the fracture surface has a cleavage mode.展开更多
The fiber laser welding tests for 3 mm thick TC4 titanium alloy plates are carried out,and the microstructures of the joints are analyzed by the OM and SEM,and the mechanical properties of the joints are described by ...The fiber laser welding tests for 3 mm thick TC4 titanium alloy plates are carried out,and the microstructures of the joints are analyzed by the OM and SEM,and the mechanical properties of the joints are described by tensile and hardness tests,and the SEM morpho-logies of the tensile fracture are observed.The results show that the weld zone is composed of columnarβphase with coarse grains and acicular martensiteα',and small secondaryα'phases in different directions are formed acicular martensiteα'.The microstructure at the boundary between the HAZ and the weld is composed ofα'andαphases,the microstructure at the boundary between the HAZ and the base metal is composed of the initial(αandβ)andαphases,and the microstructure of the middle transition zone of the HAZ is composed of a small amount ofα'andαphase of high temperatureβphase’transformation and initial(αandβ)phases.The average tensile strength of TC4 titanium alloy laser beam welded joints is 1056 MPa,and the average elongation is 9.0%,which are lower than the tensile strength and the elongation of the base metal respectively.The fracture is ductile fracture,and the hardness of the weld zone is the highest and that of the HAZ is the lowest.展开更多
基金Supported by the Intermetallic Compound Welding Research Pro-ject (No. 1205017)
文摘Ti-23Al-17Nb alloy is an important high temperature structural material used in the space and aerospace fields. Welding of this alloy is an indispensable processing method, so the microstructures and mechanical properties of these welded joints must be studied to improve the welds. Longitudinal three-point bending tests were conducted to measure the bending ductility of laser beam welded joints. The crack distribution and fracture surface were investigated to further analyze the fracture behavior. The results indicate that the bending ductility decreases as the heat input by the laser beam welding increases. The crack inducing strain reaches 4.24%, while the fracturing strain exceeds 5% when the heat input is below 316 J/cm. If the columnar crystal grain of the weld metal exhibits a uniform orientation, the bending ductility is worse. The fractography analysis shows that the cracking propagates transgranularly and the fracture surface has a cleavage mode.
基金supported by the Science and Technology Plan Foundation of Guizhou(Guizhou Science Support[2021]General 337)Anhui University Natural Science Key Research Project(2022AH052357).
文摘The fiber laser welding tests for 3 mm thick TC4 titanium alloy plates are carried out,and the microstructures of the joints are analyzed by the OM and SEM,and the mechanical properties of the joints are described by tensile and hardness tests,and the SEM morpho-logies of the tensile fracture are observed.The results show that the weld zone is composed of columnarβphase with coarse grains and acicular martensiteα',and small secondaryα'phases in different directions are formed acicular martensiteα'.The microstructure at the boundary between the HAZ and the weld is composed ofα'andαphases,the microstructure at the boundary between the HAZ and the base metal is composed of the initial(αandβ)andαphases,and the microstructure of the middle transition zone of the HAZ is composed of a small amount ofα'andαphase of high temperatureβphase’transformation and initial(αandβ)phases.The average tensile strength of TC4 titanium alloy laser beam welded joints is 1056 MPa,and the average elongation is 9.0%,which are lower than the tensile strength and the elongation of the base metal respectively.The fracture is ductile fracture,and the hardness of the weld zone is the highest and that of the HAZ is the lowest.
