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CuTiNiZrV Amorphous Alloy Foils for Vacuum Brazing of TiAl Alloy to 40Cr Steel

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Journal of Materials Science & Technology 2015年第2期31卷 217-222页

作者： Honggang Dong Zhonglin Yang Zengrui Wang Dewei Deng Chuang Dong School of Materials Science and Engineering Dalian University of Technology State Key Laboratory of Advanced Welding and joining Harbin Institute of Technology Key Lab of Materials Modi fi cation (Dalian University of Technology) Ministry of Education

Vacuum brazing of TiAl alloy to 40Cr steel sheets was conducted with newly developed CuTiNiZrV amorphous foils. It was found that a diffusion layer,filler metal and reaction layer existed in the brazed seam. The diffusion layer in the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25(at.%) foil was flat and thin,containing Ti19Al6 and Ti2Cu intermetallic compounds; however,the diffusion layer brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil was uneven with bulges,consisting of essentially Ti-based solute solution. The foil with 12.5 at.% V showed inferior spreadability compared to that with 6.25 at.% V at brazing temperature. However,fracture happened along the diffusion layer with 6.25 at.% V foil due to the formation of brittle intermetallic phases,but the joints brazed with 12.5 at.% V foil failed through the TiAl substrate. These results show that designing amorphous alloy with less Ti and more V for brazing TiAl alloy to steel is appropriate.

关键词： Titanium aluminide Steel dissimilar metal joining

Microstructure characteristics of dissimilar metal weld between aluminum alloy and brass

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China Welding 2013年第3期22卷 1-5页

作者：董红刚张旭超胡文金杨继承 School of Materials Science and Engineering Dalian University of Technology Dalian 116024 Dalian Shipbuilding Industry Co. Ltd. Ship Design & Research Institute Dalian 116005

dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.

关键词： dissimilar metal joining aluminum brass interface microstructure

joining of AZ31 and AZ91 Mg alloys by friction stir welding

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Journal of Magnesium and Alloys 2015年第4期3卷 330-334页

作者： B.Ratna Sunil G.Pradeep Kumar Reddy A.S.N.Mounika P.Navya Sree P.Rama Pinneswari I.Ambica R.Ajay Babu P.Amarnadh Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 521202India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India

Two dissimilar magnesium(Mg)alloy sheets,one with low aluminium(AZ31)and another with high aluminium(AZ91)content,were successfully joined by friction stir welding(FSW).The effect of process parameters on the formation of hot cracks was investigated.A sound metallurgical joint was obtained at optimized process parameters(1400 rpm with 25 mm/min feed)which contained fine grains and distributed β(Mg_(17)Al_(12))phase within the nugget *** increasing trend in the hardness measurements has also confirmed more amount of dissolution of aluminium within the nugget zone.A sharp interface between nugget zone and thermo mechanical affected zone(TMAZ)was clearly noticed at the AZ31 Mg alloy side(advancing)but not on the AZ91 Mg alloy side(retreating).From the results it can be concluded that FSW can be effectively used to join dissimilar metals,particularly difficult to process metals such as Mg alloys,and hot cracking can be completely eliminated by choosing appropriate process parameters to achieve sound joint.

关键词： dissimilar metal joining Magnesium alloys Friction stir welding AZ31 AZ91

Microstructures and mechanical properties of metal inert-gas arc welded Mg-steel dissimilar joints

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Transactions of Nonferrous metals Society of China 2015年第8期25卷 2533-2542页

作者：汪晓勇孙大千殷世强刘东阳吉林大学材料科学与工程学院汽车材料教育部重点实验室长春130025

The joining of Mg alloy to steel was realized by metal inert-gas arc welding, and the weld thermal cycle characteristics and Mg-steel joints were investigated. The results show that the temperature distribution in the joints is uneven. Mg alloy welds present a fine equiaxed grain structure. There exists a transition layer consisting mainly of AlFe, AlFe3 and Mg（Fe, Al）2O4 phases at Mg/steel interface, and it is the weakest link in Mg？steel joints. The welding heat input and weld Al content have the significant effect on the joint strength. The joint strength increases with increasing the heat input from 1680 J/cm to 2093 J/cm, due to promoting Mg/steel interface reaction. When weld Al content is increased to 6.20%, the joint strength reaches 192 MPa, 80% of Mg alloy base metal strength. It is favorable to select the suitable welding heat input and weld Al content for improving joint strength.

关键词： AZ31B Mg alloy Q235 steel metal inert-gas arc welding dissimilar metal joining

Microstructure and mechanical properties of friction welds between TiA l alloy and 40Cr steel rods

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Transactions of Nonferrous metals Society of China 2014年第10期24卷 3126-3133页

作者：董红刚于连震高洪明邓德伟周文龙董闯大连理工大学材料与科学工程学院大连116085 哈尔滨工业大学先进焊接与连接国家重点实验室哈尔滨150001 大连理工大学三束材料改性教育部重点实验室大连116085

Direct friction welding of Ti Al alloy to 40 Cr steel rods was conducted, and the microstructure and mechanical properties of the resultant joints in as-welded and post-weld heat treatment（PWHT） states were investigated. The martensitic transformation occurred and brittle Ti C phase formed near the interface due to C agglomeration, which degraded the joint strength and increased the microhardness at the interface in as-welded state. Feathery and Widmanstatten structure generated near the interface on Ti Al alloy side. After PWHT at 580 °C and 630 °C for 2 h, the sorbite formed and C dispersed at the interface, leading to the increase of the joint strength from 86 MPa in as-welded state to 395 MPa and 330 MPa, respectively. The heat-treated specimen fractured with quasi-cleavage features through the zone 1 mm away from the interface on TiA l alloy side, but the as-welded specimen failed through the interface.

关键词： TiAl alloy steel dissimilar metal joining friction welding post-weld heat treatment

Welding of shape memory alloy to stainless steel for medical occluder

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Transactions of Nonferrous metals Society of China 2013年第1期23卷 156-160页

作者：吕世雄杨仲林董红刚哈尔滨工业大学先进焊接国家重点实验室哈尔滨150001 大连理工大学材料科学与工程学院大连116085

dissimilar metal joining between NiTi shape memory alloy（SMA） and stainless steel was conducted.A cluster of NiTi SMA wires were first joined with tungsten inert gas（TIG） welding process,then the NiTi SMA TIG weld was welded to a stainless steel pipe with laser spot welding *** microstructure of the welds was examined with an optical microscope and the elemental distribution in the welds was measured by electron probe microanalysis（EPMA）.The results show that TiC compounds dispersively distribute in the NiTi SMA TIG ***,the amount of TiC compounds greatly decreases around the fusion boundary of the laser spot weld between the NiTi SMA and stainless *** diffusion between NiTi shape memory alloy and stainless steel happen within a short distance near the fusion boundary,and intermetallic compounds such as Ni3Ti＋（Fe,Ni）Ti appear around the fusion boundary.

关键词： medical occluder NiTi alloy shape memory alloy stainless steel laser spot welding dissimilar metal joining Ni3Ti (Fe Ni)Ti