镀锡银钎料钎焊316LN不锈钢的接头组织及力学性能
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摘要
通过在BAg34CuZnSn钎料(3.5%Sn,质量分数)基材表面刷镀微米锡层,采用感应钎焊方法对316LN不锈钢进行连接。利用扫描电镜(SEM)和X射线衍射仪(XRD)分析基材表面锡镀层的结晶取向和界面形貌,以及316LN不锈钢钎焊接头的显微组织、物相组成、断口形貌,并借助万能拉力试验机测试了钎焊接头的力学性能。结果表明,基材表面锡镀层结晶晶粒呈现明显的(200),(112)择优取向。BAg34CuZnSn基材钎料和5.0%Sn含量镀锡银钎料连接的316LN不锈钢钎焊接头组织主要由Ag相、富Cu相、CuZn相、Cu_5Zn_8相组成;当镀锡银钎料中Sn含量为6.4%时,316LN不锈钢钎焊接头组织主要由Ag相、富Cu相、CuZn相、Cu_5Zn_8相、Cu_(41)Sn_(11)相和Ag_3Sn相组成。镀锡后316LN不锈钢钎焊接头的抗拉强度高于基材钎料连接的接头强度,且随着镀锡银钎料中Sn含量逐渐升高,316LN不锈钢钎焊接头的抗拉强度呈现先升高后降低的趋势。在镀锡银钎料中Sn含量为5.5%时,钎焊接头的抗拉强度最高,为415 MPa。镀锡不改变316LN不锈钢钎焊接头的断口特征,镀锡前后316LN不锈钢钎焊接头的拉伸断口均呈现以韧性断裂为主脆性断裂为辅的混合断裂特征。
316LN stainless steels were induction brazed successfully using BAg34CuZnSn( 3. 5% Sn content,mass fraction) brazing alloys with tin brush-plated coatings. Scanning electron microscope( SEM) and X-ray diffraction( XRD) were used to analyze the interface morphology and crystalline orientation of tin coating on the surface of base brazing alloys and observe the microstructure,phase composition and fracture morphology of 316 LN stainless steel brazed joints. The tensile strength of brazed joints was analyzed using tensile test machine. The results showed that the crystallization orientation of tin coating displayed( 200) and( 112) crystal faces. The microstructure of 316 LN stainless steel brazed joints using BAg34CuZnSn base brazing alloys and 5. 0%( mass fraction) silver brazing alloys with plating tin was composed of Ag phase,Cu-rich phase,CuZn compound phase and Cu_5Zn_8 compound phase. The structure of316 LN stainless steels brazed joints was composed of Ag phase,Cu-rich phase,CuZn compound phase,Cu_5Zn_8 compound phase,Cu_(41)Sn_(11) compound phase and Ag_3Sn compound phase when tin content of silver brazing alloys was 6. 4%( mass fraction). The tensile strength of substrate brazing alloys was lower than silver brazing filler metals with plating tin. The tensile strength of brazed joints initially increased and then decreased with the increase of plating tin content. When silver brazing alloys contained 5. 5%( mass fraction)tin,the maximum tensile strength of 316 LN stainless steels brazed joints was 415 MPa. Fracture characteristic of 316 LN stainless steel was not changed with the introduction of brush plating tin. The fracture morphology of 316 LN stainless steels brazed joints using silver brazing filler metals with plating tin mainly displayed ductile fracture which was the same as the brazed joints using the BAg34CuZnSn substrate brazing filler metals.
316LN stainless steels were induction brazed successfully using BAg34CuZnSn( 3. 5% Sn content,mass fraction) brazing alloys with tin brush-plated coatings. Scanning electron microscope( SEM) and X-ray diffraction( XRD) were used to analyze the interface morphology and crystalline orientation of tin coating on the surface of base brazing alloys and observe the microstructure,phase composition and fracture morphology of 316 LN stainless steel brazed joints. The tensile strength of brazed joints was analyzed using tensile test machine. The results showed that the crystallization orientation of tin coating displayed( 200) and( 112) crystal faces. The microstructure of 316 LN stainless steel brazed joints using BAg34CuZnSn base brazing alloys and 5. 0%( mass fraction) silver brazing alloys with plating tin was composed of Ag phase,Cu-rich phase,CuZn compound phase and Cu_5Zn_8 compound phase. The structure of316 LN stainless steels brazed joints was composed of Ag phase,Cu-rich phase,CuZn compound phase,Cu_5Zn_8 compound phase,Cu_(41)Sn_(11) compound phase and Ag_3Sn compound phase when tin content of silver brazing alloys was 6. 4%( mass fraction). The tensile strength of substrate brazing alloys was lower than silver brazing filler metals with plating tin. The tensile strength of brazed joints initially increased and then decreased with the increase of plating tin content. When silver brazing alloys contained 5. 5%( mass fraction)tin,the maximum tensile strength of 316 LN stainless steels brazed joints was 415 MPa. Fracture characteristic of 316 LN stainless steel was not changed with the introduction of brush plating tin. The fracture morphology of 316 LN stainless steels brazed joints using silver brazing filler metals with plating tin mainly displayed ductile fracture which was the same as the brazed joints using the BAg34CuZnSn substrate brazing filler metals.
引文
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[13]Wang X X,Du Q B,Long W M,LüD F.Effect of micro tin brush-electroplated coating on properties of Ag Cu Zn Sn brazing filler metals[J].Transactions of the China Welding Institution,2015,36(3):47.(王星星,杜全斌,龙伟民,吕登峰.微米锡刷镀层对Ag Cu Zn Sn钎料性能的影响[J].焊接学报,2015,36(3):47.)
[14]Wang X X,Long W M,Ma J,LüD F.Effect of electroplated tin coating on properties of BAg50Cu Zn brazing filler metal[J].Transactions of the China Welding Institution,2014,35(9):61.(王星星,龙伟民,马佳,吕登峰.锡镀层对BAg50Cu Zn钎料性能的影响[J].焊接学报,2014,35(9):61.)
[15]Wang X X,Li Q C,Long W M,Nie K B,Tang M Q.Effect of heat diffusion process on the interface microstructure and melting characteristic of brazing filler metals with tin coatings[J].Transactions of the China Welding Institution,2016,37(5):89.(王星星,李权才,龙伟民,聂凯波,唐明奇.热扩散对镀锡银钎料界面组织及熔化特性的影响[J].焊接学报,2016,37(5):89.)
[2]Zhang G X,Long W M,He P,Cui Y Y,She C.Brazing properties of silver based filler metal with different carbon contents[J].Chinese Journal of Rare Metals,2015,39(6):527.(张冠星,龙伟民,何鹏,崔艳艳,佘春.不同碳含量对银钎料钎焊性能的影响[J].稀有金属,2015,39(6):527.)
[3]Watanabe T,Yanagisawa A,Sasaki T.Development of Ag based brazing filler metal with low melting point[J].Science and Technology of Welding and Joining,2011,16(6):502.
[4]Cao J,Zhang L X,Wang H Q,Wu L Z,Feng J C.Effect of silver content on microstructure and properties of brass/steel induction brazing joint using Ag-Cu-Zn-Sn filler metal[J].Journal of Materials Science&Technology,2011,27(4):377.
[5]Winiowski A,Rózanski M.Impact of tin and nickel on the brazing properties of silver filler metals and on the strength of brazed joints made of stainless steels[J].Archives of Metallurgy and Materials,2013,58(4):1007.
[6]Lai Z M,Xue S B,Han X P,Gu L Y,Gu W H.Study on microstructure and property of brazed joint of Ag Cu Zn-X(Ga,Sn,In,Ni)brazing alloy[J].Rare Metal Materials and Engineering,2010,39(3):397.
[7]Ma J,Long W M,He P,Bao L,Xue P,Wu M F.Effect of gallium addition on microstructure and properties of Ag-Cu-Zn-Sn alloys[J].China Welding(English Edition),2015,24(3):6.
[8]Sui F F,Long W M,Liu S X,Zhang G X,Bao L,Li H,Chen Y.Effect of calcium on the microstructure and mechanical properties of brazed joint using Ag-Cu-Zn brazing filler metal[J].Materials&Design,2013,46:605.
[9]Zhang G X,Long W M,Pan J J,Li H.Effect of oxygen content on wettability and mechanical property of brazing seam for silver based powdered brazing filler metal[J].Transactions of the China Welding Institution,2014,35(3):81.(张冠星,龙伟民,潘建军,李浩.氧含量对银基粉状钎料润湿性及钎缝力学性能的影响[J].焊接学报,2014,35(3):81.)
[10]Chen Y,Yun D,Sui F,Long W,Zhang G,Liu S.Influence of sulphur on the microstructure and propertiesof Ag-Cu-Zn brazing filler metal[J].Materials Science and Technology(United Kingdom),2013,29(10):1267.
[11]Wierzbicki L J,Malec W,Stobrawa J,Cwolek B,Juszczyk B.Studies into new,environmentally friendly AgCu-Zn-Sn brazing alloys of low silver content[J].Archives of Metallurgy and Materials,2011,56(1):147.
[12]Li M G,Sun D Q,Qiu X M,Yin S Q.Effect of tin on melting temperature and microstructure of Ag-Cu-Zn-Sn filler metals[J].Materials Science and Technology,2005,21(11):1318.
[13]Wang X X,Du Q B,Long W M,LüD F.Effect of micro tin brush-electroplated coating on properties of Ag Cu Zn Sn brazing filler metals[J].Transactions of the China Welding Institution,2015,36(3):47.(王星星,杜全斌,龙伟民,吕登峰.微米锡刷镀层对Ag Cu Zn Sn钎料性能的影响[J].焊接学报,2015,36(3):47.)
[14]Wang X X,Long W M,Ma J,LüD F.Effect of electroplated tin coating on properties of BAg50Cu Zn brazing filler metal[J].Transactions of the China Welding Institution,2014,35(9):61.(王星星,龙伟民,马佳,吕登峰.锡镀层对BAg50Cu Zn钎料性能的影响[J].焊接学报,2014,35(9):61.)
[15]Wang X X,Li Q C,Long W M,Nie K B,Tang M Q.Effect of heat diffusion process on the interface microstructure and melting characteristic of brazing filler metals with tin coatings[J].Transactions of the China Welding Institution,2016,37(5):89.(王星星,李权才,龙伟民,聂凯波,唐明奇.热扩散对镀锡银钎料界面组织及熔化特性的影响[J].焊接学报,2016,37(5):89.)