Interfacial structure and bond strength of ultrasonic brazed Al–304 stainless steel dissimilar joints

Abstract

A filler alloy (Zn–14 at.-%Al) was used to join aluminium to 304 type stainless steel by ultrasonic brazing at 673 K for different ultrasound application times. Different reaction layers could be observed at the interface, containing Fe–Al, Fe–Zn, and Al–Zn solid solutions. As the amount of these solid solutions increased at the interface, there was a gradual improvement in the joint bond strength. The maximum bond strength of 146 MPa was obtained for the Al–304 joint brazed at 673 K for 3 s ultrasound application time. A critical remaining thickness of the filler alloy after ultrasonic application improves the interfacial joining. Extending the ultrasound application time beyond 3 s causes a bulk escape of the brazing alloy from the interface and leads to a direct interaction between aluminium and 304, which increases the possibility of forming intermetallics, and consequently decreases the joint bond strength.     

Characterization of High-Frequency Induction Brazed Magnesium Alloy Joint with an Al-Mg-Zn Filler Metal

In this paper, a novel Al-Mg-Zn filler metal was designed to join magnesium alloy AZ31B plates by means of high-frequency induction brazing in argon gas shield condition. The microstructure and the mechanical properties of the brazed joint were investigated. The experimental results showed that the brazed joint contained large amount of α-Mg and β-Mg₁₇(Al, Zn)₁₂ phases. The homogeneous Mg₃₂(Al, Zn)₄₉ phase in the original filler metal was consumed due to the intensive alloying during the brazing process. The results indicate that the shear strength of the brazed joint is 35 MPa. The fracture morphology of the brazed joint exhibits intergranular fracture mode, and the fracture originates from the hard β-Mg₁₇(Al, Zn)₁₂ phase.     

Microstructure and strength of brazed joints of TiB2 cermet to TiAl-based alloys

In this study, TiB2 cermet and TiAl-based alloy are vacuum brazed successfully by using Ag-Cu-Ti filler metal.The microstructural analyses indicate that two reaction products, Ti ( Cu, Al ) 2 and Ag bused solid solution ( Ag ( s. s ) ) , are present in the brazing seam, and the iuterface structure of the brazed joint is TiB2/TiB2 Ag ( s. s ) /Ag ( s. s ) Ti ( Cu,Al)2/Ti( Cu, Al)2/TiAl. The experimental results show that the shear strength of the brazed TiB2/TiAl joints decreases us thebrazing time increases at a definite brazing temperature. When the joint is brazed at 1 223 K for 5 min, a joint strength up to 173 MPa is achieved.     

SiCp/Al复合材料与Fe36Ni合金超声波钎焊

利用超声波钎焊方法使用ZnAlSi钎料实现了Fe36Ni合金与45%SiC_p/2024Al和55%SiC_p/A356两种复合材料的连接,并得到由SiC颗粒增强的复合焊缝.通过扫描电镜、能谱等方法对焊缝的微观结构以及断口形貌进行了观察,对接头的压剪强度进行了测试,分析了Fe36Ni与两种复合材料钎焊接头微观组织和接头强度的差异.结果表明,在Fe36Ni与两种复合材料的钎缝中,钎料与两侧母材界面均形成良好的冶金结合,SiC颗粒均匀分布于焊缝中.Fe36Ni与45%SiC_p/2024Al的接头抗剪强度为110~145 MPa,Fe36Ni与55%SiC_p/A356的接头抗剪强度为75~85 MPa.Fe36Ni与45%SiC_p/2024Al的接头断裂位置为钎缝中,而Fe36Ni与55%SiC_p/A356的接头断裂位置位于Fe36Ni与钎料的界面上.     

Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu_43.75Ti_37.5Ni_6.25Zr_6.25V_6.25 foil was 105 MPa and that with Cu_37.5Ti₂₅Ni_12.5Zr_12.5V_12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr₄Ti, Cu_0.8FeTi, Fe₈TiZr₃ and Al₂NiTi₃C compounds were found in the fractured joint brazed with Cu_43.75Ti_37.5Ni_6.25Zr_6.25V_6.25 foil, and Fe₂Ti, TiCu, Fe₈TiZr₃ and NiTi_0.8Zr_0.3 compounds were detected in the joint brazed with Cu_37.5Ti₂₅Ni_12.5Zr_12.5V_12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.     

Al2O3/SUS304 Brazing via AgCuTi-W Composite as Active Filler

Alumina ceramic (α-Al₂O₃) was brazed to stainless steel (SUS304) using an Ag-Cu-Ti + W composite filler and a traditional active brazing filler alloy (CuSil-ABA). Then, the effects of the presence of W particles and of the brazing parameters on the microstructures and mechanical properties of the brazed joints were investigated. The maximum tensile strength of the joints obtained using Ag-Cu-Ti + W composite filler was 13.2 MPa, which is similar to that obtained using CuSil-ABA filler (13.5 MPa). When the joint was brazed at 930 °C for 30 min, the tensile strengths decreased for both kinds of fillers, although the strength was slightly higher for the Ag-Cu-Ti + W composite filler than for the Ag-Cu-Ti filler. The interfacial microstructure results show that the Ti reacts with W to form a Ti-W-O compound in the brazing alloy. When there are more W particles in the brazing alloy, the thickness of the Ti _X O _Y reaction layer near the alumina ceramic decreases. Moreover, W particles added to the brazing alloy can reduce the coefficient of thermal expansion of the brazing alloy, which results in lower residual stress between the Al₂O₃ and SUS304 in the brazing joints and thus yields higher tensile strengths as compared to those obtained using the CuSil-ABA brazing alloy.     

TiAl与Ni基合金接触反应钎焊接头界面组织及性能

以Ti为中间层实现了TiAl与Ni基合金的接触反应钎焊。采用扫描电镜和电子探针等手段对钎焊接头的界面结构及生成相进行分析,并对接头剪切强度进行测试。结果表明:当钎焊温度为960℃时,钎缝主要由Tiss和Ti2Ni组成;当钎焊温度从960℃升高到1000℃时,钎缝中生成Ti-Al及Al-Ni-Ti化合物,典型界面结构为:GH99/(Ni,Cr)ss/Ti2Ni+AlNi2Ti+TiNi/Ti3Al+Al3NiTi2/Ti3Al+Al3NiTi2/TiAl;钎焊温度继续升高,Ti3Al和Al3NiTi2变得粗大,导致接头性能下降。当钎焊温度为1000℃,保温10min时,接头剪切强度达到最大值233MPa。随钎焊温度的升高,钎缝厚度先增加后减小。     

Ag-Cu-Sn-Ti活性钎焊Gr/2024Al复合材料与TC4钛合金

采用自制的AgCuSnTi钎料对发汗材料Gr/2024Al复合材料和TC4钛合金进行钎焊,对焊后接头界面组织及力学性能进行了分析.结果表明,接头典型界面组织为Gr/2024Al/Ti₃AlC₂/Ag₂Al+Ag₃Sn+Al₂Cu+Al₅CuTi₂/Al₅CuTi₂+Ag₃Sn/TC4.钎焊时,活性元素Ti与Gr/2024Al复合材料的石墨基体发生活性反应,实现了TC4与Gr/2024Al复合材料的低温连接,保证了复合材料的力学性能及发汗功能.随钎焊温度升高及保温时间延长,钎缝组织中弥散分布的Al₅CuTi₂化合物聚集长大成块状,使接头性能下降.当钎焊温度为680℃,保温时间为10min时接头抗剪强度达到最大值17MPa,其为Gr/2024Al复合材料母材强度的70%.     

Cold metal transfer welding–brazing of magnesium to pure copper

Magnesium alloy AZ31B and pure copper T2 were lapped and joined by cold metal transfer (CMT) welding–brazing method by AZ61A magnesium alloy wire with a 1·2 mm diameter. Results indicated that a satisfied Mg/Cu CMT welding–brazing joint was obtained in the stable welding processes with no spatter. The joint was composed of Mg–Mg welding joint formed between the Mg weld metal and the Mg base metal, and Mg–Cu brazing joint formed between the Mg weld metal and the local molten Cu base metal. The microstructure and the intermetallic compound (IMC) distribution were inspected and analysed in detail. The interfacial reaction layers of the brazing joint consisted of Mg₂Cu, Al₆Cu₄Mg₅, MgCu₂ and Mg₁₇Al₁₂ IMCs. The tensile shear strength of the Mg/Cu CMT welding–brazing joint could reach 172·5 N mm^?1. In addition, two different fracture modes were observed: at the fusion zone and at the brazing interface.     

中间层对高体积分数SiCp/Al复合材料真空钎焊的影响

采用铜箔、Al-Si-Mg及Al-Si-Mg/Cu/Al-Si-Mg(简称ACA)3种不同中间层对高体积分数45%SiC_p/Al复合材料进行真空钎焊连接研究.通过SEM,EDS及XRD等方法对钎缝的微观结构及界面组织进行了分析,研究了中间层种类对钎焊接头微观结构、界面组织以及连接强度的影响,阐明了不同中间层钎焊连接45%SiC_p/Al复合材料的界面形成过程及接头断裂机制.结果表明,ACA中间层兼具了铜和Al-Si-Mg钎料的优点,可降低钎料的液相线,增加其流动性,通过Cu原子优先在铝合金基体与其氧化膜的界面处扩散发生共晶反应,增强钎料的去膜作用,从而实现高体积分数45%SiC_p/Al复合材料的高质量连接.     

Effect of Ti content in Ag–Cu–Ti activated filler metal on dissimilar joint formation of sialon and WC–Co alloy by laser brazing

Laser brazing was carried out for dissimilar joining of sialon and a WC–Co alloy. Eutectic type Ag–Cu alloys as filler metals with different Ti content ranging from 0 to 2·8 mass-% were used to investigate the effects of Ti on the interface structure and strength of the joint. The filler metal sheet was sandwiched between a sialon block and a WC–Co alloy plate, and a laser beam was irradiated selectively on the WC–Co alloy plate. The brazed joint was obtained using the filler metal containing >0·3 mass-%Ti. TiN, Ti₅Si₃, and Cu₄Ti layers were formed at the interface of sialon and brazed metal as compound layers. The shear strength of the brazed joint increased with increasing Ti content in the filler metal in the range 0·3–1·7 mass-%, reaching a maximum value of 106 MPa. However, the strength decreased when the Ti content became higher than 1·7 mass-%.     

SiCp/A356复合材料超声波辅助钎焊

利用超声波辅助钎焊的方法实现了Zn-Al合金与体积分数55%SiCp/A356复合材料的连接,并得到了由SiC陶瓷颗粒增强的复合焊缝.通过扫描电镜、能谱等方法对焊缝的微观结构进行了描述,研究了超声波作用时间对焊接接头微观组织结构及连接强度的影响规律,建立了超声波作用下复合焊缝形成过程的物理模型.当焊接温度为475℃,超声波作用时间为20 s时钎焊焊缝的平均抗剪强度值为231 MPa.由SiC陶瓷增强的复合焊缝其室温抗剪强度与无增强相颗粒的纯合金焊缝强度相比提高了50%.结果表明,焊缝中铝含量的增加及陶瓷颗粒的增强作用是导致焊缝强度提高的两个重要因素.     

Laser brazing of alloy 600 with precious filler metals

Abstract

The diode laser brazing of Ni base heat resistant alloy with precious filler metals has been conducted using the tandem beam for preheating and brazing. A couple of 1 mm thick plates of alloy 600 (Inconel 600) were butt brazed using Au–18Ni, Ag–10Pd and Ag–21Cu–25Pd filler metals of 0·5 mm diameter with a brazing flux. Sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at brazing clearances of 0·1–1·5 mm. The tensile strength of the braze joint produced using Ag–Pd filler metal increased with decreasing brazing clearance and reached ～70% of the base metal strength at a brazing clearance of 0·1 mm while those obtained by using Au–Ni and Ag–Cu–Pd filler metals were comparable with the base metal strength at any clearances between 0·1 and 1·5 mm. The laser brazing technique could be successfully applied to the brazing of Ni base superalloy to attain a joint with high performance and reliability.     

Infrared brazing of Fe3Al intermetallic compound using gold-based braze alloy

Infrared-brazing Fe₃Al with Au–44Cu as filler metal has been investigated. The brazed joint consists mainly of a β-phase, Au_8 − x Cu_4 + x Al₄, caused by the dissolution of Al from Fe₃Al substrate into the braze alloy. The depletion of Al from Fe₃Al substrate results in the formation of a layer of β-phase particles dispersed in the Fe-rich phase. The highest shear strength for AuCu filler is 327 MPa for specimens infrared brazed at 880°C for 180 s. The brazed joint is mainly fractured along the central β-phase in which the fractograph exhibits quasi-cleavage with dimples. Increasing the brazing time or temperature will deteriorate the bonding strength of the joint, and the fracture mode is prone to cleavage of brittle fracture. Au–44Cu filler demonstrates a great potential for bonding Fe₃Al intermetallic compound.     

Effect of Ce Addition on the Microstructure and Properties of Ag17CuZnSn Filler Metal

The effect of trace amounts of rare earth element Ce on the wettability, mechanical properties and microstructure of Ag17CuZnSn filler metal was investigated systematically by means of microstructure and spectroscopic characterizations. H62 brass and 304 stainless steel were brazed with Ag17CuZnSn-xCe filler metals. The results indicate that wettability and oxidation resistance of filler metal are remarkably improved with adding trace amount of Ce. The shear strength of brazed joint increases 29% compared to that of brazed joint without adding Ce. Moreover, it is observed that the trace amount of Ce in Ag17CuZnSn filler metal refines the brazed joint matrix microstructure. The elements diffusion is examined during the brazing process. More Ce can diffuse into the stainless steel than that of either Cu or Zn. Compared to the Cu solid solution, Fe prefers to diffuse into the Ag solid solution. When the Ce content is 0.3 wt.%, some bright and brittle Ce-bearing particles appear in the bottom of dimples which deteriorate the shear strength of brazed joint. The results of this study can stimulate the use of low-silver brazing filler metals for various applications.     

超声振动对含LPSO结构的Mg98Y1.0Ni0.5Al0.5合金显微组织与力学性能的影响(英文)

低Y、Ni含量的LPSO结构增强镁合金具有低成本、优异力学性能的特点。为进一步提升其综合力学性能,掺杂Al元素及熔体超声振动处理是可行的途径。通过扫描电子显微镜、能谱分析、透射电子显微镜、X射线衍射和纳米压痕测试研究掺杂Al元素后低Y、Ni含量的Mg98Y1.0Ni0.5Al0.5合金的显微组织,对比超声振动对显微组织与力学性能的影响。掺杂Al后LPSO结构的含量降低,且在块状LPSO结构相邻处析出圆整的Al₂NiY相。Al₂NiY相与LPSO结构和Mg基体在界面处均不共格。通过对熔体施加超声振动处理后,Al₂NiY相被有效细化为短片状,并均匀分布在基体中,阻碍微裂纹的产生和扩展,从而提高Mg₉₈Ni_0.5Y_1.0Al_0.5合金的力学性能。与未经超声处理Mg₉₈Ni_0.5Y_1.0Al_0.5合金相比,其极限抗拉强度和伸长率提升至187 MPa和7.9...     

基于银合金先导润湿的铜磷钎料钎焊钢分析

基于低熔点合金先导润湿的原理,设计制备了一种表面覆盖低熔点银合金层的新型铜磷焊片.采用该焊片钎焊45碳钢,分析了界面反应机理及钎焊接头性能,并和使用普通铜磷焊片钎焊的碳钢接头进行了对比.结果表明,表面覆盖的低熔点银合金早于铜磷合金熔化润湿碳钢基体,并形成反应层,铜磷钎料熔化后与银合金层反应熔合,冷却后形成良好的冶金连接;与使用铜磷钎料直接钎焊的接头相比,银合金先导润湿钎焊的铜磷/碳钢界面化合物层厚度明显减小,抗剪强度超过160 MPa,断裂发生在靠近连接界面的钎焊材料内部,接头强韧性显著改善.     

Microstructure and mechanical properties of Cu/Al joints brazed using (Cu,Ni, Zr,Er)-modified Al—Si filler alloys

To design a promising Al—Si filler alloy with a relatively low melting-point, good strength and plasticity for the Cu/Al joint, the Cu, Ni, Zr and Er elements were innovatively added to modify the traditional Al—Si eutectic filler. The microstructure and mechanical properties of filler alloys and Cu/Al joints were investigated. The result indicated that the Al—Si—Ni—Cu filler alloys mainly consisted of Al(s,s), Al₂(Cu,Ni) and Si(s,s). The Al—10Si—2Ni—6Cu filler alloy exhibited relatively low solidus (521 °C) and liquidus (577 °C) temperature, good tensile strength (305.8 MPa) and fracture elongation (8.5%). The corresponding Cu/Al joint brazed using Al—10Si—2Ni—6Cu filler was mainly composed of Al₈(Mn,Fe)₂Si, Al₂(Cu,Ni)₃, Al(Cu,Ni), Al₂(Cu,Ni) and Al(s,s), yielding a shear strength of (90.3±10.7) MPa. The joint strength was further improved to (94.6±2.5) MPa when the joint was brazed using the Al—10Si—2Ni—6Cu—0.2Er—0.2Zr filler alloy. Consequently, the (Cu, Ni, Zr, Er)-modified Al—Si filler alloy was suitable for obtaining high-quality Cu/Al brazed joints.     

Effect of brazing temperature and brazing time on the microstructure and tensile strength of TiAl-based alloy joints with Ti-Zr-Cu-Ni amorphous alloy as filler metal

An amorphous Ti-37.5Zr-15Cu-15Ni (wt.%) ribbon fabricated by vacuum arc remelting and rapid solidification was used as filler metal to vacuum braze TiAl alloy (Ti-45Al-2Mn-2Nb-1B (at.%)). The effects of brazing temperature and time on the microstructure and strength of the joints were investigated in details. The typical brazed joint major consisted of three zones and the brazed joints mainly consisted of α_2-Ti₃Al phase, α-Ti phase and (Ti, Zr)₂(Cu, Ni) phase. When the brazing temperature varied from 910 °C to 1010 °C for 30 min, the tensile strength of the joint first increased and then decreased. With increasing the brazing time, the tensile strength of the joint increased. The maximum room temperature tensile strength was 468 MPa when the specimen was brazed at 930 °C for 60 min. All the fracture surfaces assumed typical brittle cleavage fracture characteristic. The fracture path varied with the brazing parameter and cracks preferred to initiate at (Ti, Zr)₂(Cu, Ni) phase and propagation path were mainly determined by the content and distribution of α-Ti phase and (Ti, Zr)₂(Cu, Ni) phase.     

Evolution of microstructure and phase composition of joints with ultrasonic-assisted resistance brazing

ABSTRACT

Zn–2Al alloy is used as a filler metal for brazing of aluminium 6063 alloys by ultrasonic-assisted resistance brazing (RB) technology. The evolution of the microstructure and phase composition under the effects of the electric field and ultrasonic vibration were studied. The results show that ultrasonic cavitation can remove the existing oxide films effectively and inhibit element segregation, which help obtain joints with good metallurgical bonding. In comparison to RB joints, which exhibit a coarse dendritic structure, a uniform dendritic structure was obtained in the ultrasonic-assisted resistance joints. Furthermore, the combined electric and ultrasonic field has a significant effect on grain size and on dissolution during brazing. With the application of ultrasonic vibration, the diffusion between the base metal and the Zn–2Al filler metal intensifies.