The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plastici...The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.展开更多
The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels ...The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels interlayer was carried out, and the interface microstructure evolution due to heat treatment was presented. There was not found significant interdiffusion at stainless steel/nickel interface, when the specimens were heat treated in the temperature range of 600-800 °C for 10 and 30 min, while micro-cracks occurred at the stainless steel/nickel interface heat treated at 700 °C for 30 min. The thickness of intermetallic layers at nickel/titanium alloy interface increased at 600 °C, and micro-cracks occurred at 700 and 800 °C. The micro-cracks occurred between intermetallic layers or between intermetallic layer and nickel interlayer as well. The tensile strength of the transition joint decreased with the increase of heat treatment temperature or holding time.展开更多
Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning ...Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. As a result, influences of filler metals on microstructures and mechanical properties of electron beam welded titanium-stainless steel joints were discussed. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. For each type of the filler metal, the type of solid solution and interfacial intermetallics depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti＋Ni3Ti＋NiTi2, TiFe, and Cu2Ti＋CuTi＋CuTi2 in the joints welded with Ni, V, and Cu filler metals, respectively. The tensile strengths of the joints were dependent on the hardness of the interfacial intermetallics. The joint welded with Ag filler metal had the highest tensile strength, which is about 310 MPa.展开更多
Pure commercial titanium was welded with two types of stainless steel,namely SUS 304 austenitic stainless steel and SUS 821L1 duplex stainless steel.The wavy interface of SUS 821L1 was smaller than that of SUS 304.The...Pure commercial titanium was welded with two types of stainless steel,namely SUS 304 austenitic stainless steel and SUS 821L1 duplex stainless steel.The wavy interface of SUS 821L1 was smaller than that of SUS 304.The vortex zone was observed from both longitudinal and transverse directions,and its composition was analyzed.The interface of Ti/SUS 821L11 was able to bear 401−431 MPa shear load while that of Ti/SUS 304 could withstand 352−387 MPa.The weldability window was used to analyze experimental phenomenon.Furthermore,the smoothed particle hydrodynamics(SPH)numerical simulation method was used to simulate the wavy interface.The trend of wavelength and amplitude change with strength and the stand-offs was consistent with the experimental results.展开更多
Dissimilar joints(DSJs)of ferrous and non-ferrous metals have huge technological importance in the frontiers of newdesigns in new machineries and improved design of conventional systems.This investigation was undertak...Dissimilar joints(DSJs)of ferrous and non-ferrous metals have huge technological importance in the frontiers of newdesigns in new machineries and improved design of conventional systems.This investigation was undertaken to improve mechanicalproperties of joints of two dissimilar metals:one is Ti-based and the other is Fe-based.DSJs were processed using bonding pressurefrom1to9MPa in step of2MPa at750°C for60min.Properties of the DSJs of these two metals using different mechanisms andmethods were compared with the present research for verification.Experimental results from the diffusion bonding mechanism forjoining the dissimilar metals validated the improvement in properties.Superior mechanical properties of dissimilar-metals joints wereachieved mainly due to the third non-ferrous metallic foil,Ni of^200-?m thickness,which avoided the formation of brittleFe-Ti-based intermetallics in the diffusion zone.DSJs processed are able to achieve maximum strength of^560MPa along withsubstantial ductility of^11.9%,which is the best ever reported in the literatures so far.Work hardening effect was detected in theDSJs when the bonding was processed at5MPa and above.Bulging ratio of the non-ferrous metal(Ti-based)was much higher thanthat of the ferrous metal(SS)of the DSJs processed.SEM analysis was carried out to know the details of reaction zone,while XRDwas carried out to support the SEM results.Reasons for change in mechanical,physical,and fracture properties of the DSJs with theprocess parameter variations were clarified.展开更多
基金Project(AWPT-M07)supported by State Key Laboratory of Advanced Welding and Joining,ChinaProject(20120041120015)supported by Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.
基金Project(AWPT-M07)supported by the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology
文摘The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels interlayer was carried out, and the interface microstructure evolution due to heat treatment was presented. There was not found significant interdiffusion at stainless steel/nickel interface, when the specimens were heat treated in the temperature range of 600-800 °C for 10 and 30 min, while micro-cracks occurred at the stainless steel/nickel interface heat treated at 700 °C for 30 min. The thickness of intermetallic layers at nickel/titanium alloy interface increased at 600 °C, and micro-cracks occurred at 700 and 800 °C. The micro-cracks occurred between intermetallic layers or between intermetallic layer and nickel interlayer as well. The tensile strength of the transition joint decreased with the increase of heat treatment temperature or holding time.
基金Project(2011DFR50760)supported by International Science&Technology Cooperation Program of China
文摘Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. As a result, influences of filler metals on microstructures and mechanical properties of electron beam welded titanium-stainless steel joints were discussed. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. For each type of the filler metal, the type of solid solution and interfacial intermetallics depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti＋Ni3Ti＋NiTi2, TiFe, and Cu2Ti＋CuTi＋CuTi2 in the joints welded with Ni, V, and Cu filler metals, respectively. The tensile strengths of the joints were dependent on the hardness of the interfacial intermetallics. The joint welded with Ag filler metal had the highest tensile strength, which is about 310 MPa.
文摘Pure commercial titanium was welded with two types of stainless steel,namely SUS 304 austenitic stainless steel and SUS 821L1 duplex stainless steel.The wavy interface of SUS 821L1 was smaller than that of SUS 304.The vortex zone was observed from both longitudinal and transverse directions,and its composition was analyzed.The interface of Ti/SUS 821L11 was able to bear 401−431 MPa shear load while that of Ti/SUS 304 could withstand 352−387 MPa.The weldability window was used to analyze experimental phenomenon.Furthermore,the smoothed particle hydrodynamics(SPH)numerical simulation method was used to simulate the wavy interface.The trend of wavelength and amplitude change with strength and the stand-offs was consistent with the experimental results.
文摘Dissimilar joints(DSJs)of ferrous and non-ferrous metals have huge technological importance in the frontiers of newdesigns in new machineries and improved design of conventional systems.This investigation was undertaken to improve mechanicalproperties of joints of two dissimilar metals:one is Ti-based and the other is Fe-based.DSJs were processed using bonding pressurefrom1to9MPa in step of2MPa at750°C for60min.Properties of the DSJs of these two metals using different mechanisms andmethods were compared with the present research for verification.Experimental results from the diffusion bonding mechanism forjoining the dissimilar metals validated the improvement in properties.Superior mechanical properties of dissimilar-metals joints wereachieved mainly due to the third non-ferrous metallic foil,Ni of^200-?m thickness,which avoided the formation of brittleFe-Ti-based intermetallics in the diffusion zone.DSJs processed are able to achieve maximum strength of^560MPa along withsubstantial ductility of^11.9%,which is the best ever reported in the literatures so far.Work hardening effect was detected in theDSJs when the bonding was processed at5MPa and above.Bulging ratio of the non-ferrous metal(Ti-based)was much higher thanthat of the ferrous metal(SS)of the DSJs processed.SEM analysis was carried out to know the details of reaction zone,while XRDwas carried out to support the SEM results.Reasons for change in mechanical,physical,and fracture properties of the DSJs with theprocess parameter variations were clarified.
