Influence of Alloying Elements on Interfacial Reaction and Strength of Aluminum/Steel Dissimilar Joints for Light Weight Car Body

2007 ◽  
Vol 539-543 ◽  
pp. 3888-3893 ◽  
Author(s):  
Akio Hirose ◽  
Hirotaka Imaeda ◽  
Miki Kondo ◽  
Kojiro F. Kobayashi

Dissimilar joining of Al alloys and steel was carried out using diffusion bonding process. The effects of Si and Mg contents of Al alloys and bonding parameters on the interfacial reaction were fundamentally investigated. While the reaction layers consisting of Fe-Al type intermetallic compounds (IMCs) formed at the interfacial region, in the joint with Al alloys including 1mass% Si or more a ternary Fe-Al-Si IMC layer formed at the Al alloy side. The growth of the reaction layers followed the parabolic growth low. A maximum joint strength was obtained at an average reaction layer thickness ranging from 0.5 to 1μm. The thicker reaction layer caused the fracture of the joints at a lower stress because of brittleness of the IMCs, and the thinner reaction layer including un-bonded interface also resulted in a low joint strength. As a result a thin and uniform reaction layer including less un-bonded interface can realize a high joint strength. Since the Fe-Al-Si IMC layer uniformly formed more rapidly than the binary Fe-Al IMCs in the joint with Al alloys including 1mass% Si or more, a higher joint strength was obtained at a thinner average reaction layer. As a result, it was found that the chemical compositions of 6000 series Al alloy controlled to be Mg (0.6 to 1.0mass%) and Si (more than 1.0mass%) were appropriate to obtain the better bonding characteristics.

2005 ◽  
Vol 475-479 ◽  
pp. 349-352 ◽  
Author(s):  
Akio Hirose ◽  
Fumiaki Matsui ◽  
Hirotaka Imaeda ◽  
Kojiro F. Kobayashi

In the present study, we fundamentaly analyzed the interfacial reaction and evaluated the joint strength in dissimilar diffusion bonding of Al alloys to steels. The growth of the reaction layer consisting of FeAl3 and Fe2Al5 intermetallic compounds followed the parabolic growth low. The joints with 5000 series Al alloys had a higher growth rate of the reaction layer than the joints with A6061 Al alloy. The joints of A6061 Al alloy to HT980steel had the lowest growth rate of the reaction layer. The joint strength depended on the thickness of the reaction layer. The A6061 Al alloy/steel joints had the maximum joint strength at around 1µm of average reaction layer thickness.


2015 ◽  
Vol 29 (10n11) ◽  
pp. 1540025 ◽  
Author(s):  
Xiaomin Wang ◽  
Xiaoyao Liao ◽  
Chuanping Ma ◽  
Shufang Zhang ◽  
Yan Liu ◽  
...  

Corrosion behavior of 7N01 Al alloy is sensitive to chemical composition. In this paper, stress corrosion cracking (SCC) and electrochemical behaviors of A7N01S-T5 Al alloys with three different chemical compositions were investigated. The corrosion weight loss and corrosion pits depth statistics showed that Alloy #3 (4.53 wt .% Zn , 1.27% Mg , < 0.001% Cu , 0.24% Cr , 0.15% Zr ) possesses the best anti-SCC property, while Alloy #1 (4.54% Zn , 1.09% Mg , 0.102% Cu , 0.25% Cr , 0.15% Zr ) was the weakest one. The different SCC susceptibility was mainly related to the Cu content as Alloy #3 contains higher Cu than Alloys #1 and #2. Electrochemical test result showed that Alloy #3 has higher corrosion potential and lower corrosion current density than Alloys #1 and #2. It is believed that a trace Cu can significantly improve the SC resistance of Al alloy, mainly because that Cu element can reduce the potential difference between grain inside and grain boundaries.


2014 ◽  
Vol 783-786 ◽  
pp. 2747-2752 ◽  
Author(s):  
Hiromichi T. Fujii ◽  
Yuta Goto ◽  
Yutaka S. Sato ◽  
Hiroyuki Kokawa

Dissimilar joints between 1050 Al alloy and Cu were prepared by ultrasonic spot welding technique to understand the joint characteristics. The joint strength was evaluated by tensile shear strength test. The joint strength increased with increasing joining energy and the joint produced with sufficiently high energy was fractured at the base metal region of Al alloy. The interface microstructure in Al alloy consists of severely deformed region due to ultrasonic vibration. In addition, the fine and equiaxed grains were observed near the joint interface in the specimens fractured at the base metal. These characteristics were significantly different from the microstructure in the bulk region of Al alloy. In contrast, the microstructure in Cu was hardly changed around the interface after ultrasonic welding. Additionally, thin intermetallic compound layer with the thickness of 40 nm was found to be formed at the joint interface in the specimens fractured at the base metal. Peak temperature during ultrasonic welding was found to be approximately 480 K at the interface, which was measured using embedded thermocouple.


2006 ◽  
Vol 512 ◽  
pp. 355-360
Author(s):  
Akio Hirose ◽  
Tomoyuki Hiramori ◽  
Mototaka Ito ◽  
Yoshiharu Tanii ◽  
Kojiro F. Kobayashi

Sn-3.5Ag (Sn-Ag) and Sn-3.5Ag-0.75Cu (Sn-Ag-Cu) solder balls were reflowed on electroless Ni-P/Au plated Cu pad with varying thickness of Au layer (0 to 500nm). In the Sn-Ag solder joint, a P-rich layer including voids, which resulted from Ni diffusion from the Ni-P plating to form Ni3Sn4 interfacial reaction layer, formed at the interface regardless of Au plating thickness. This caused the degradation of the joint strength. On the contrary, the Sn-Ag-Cu solder joint had no continuous P-rich layer formed and showed a higher joint strength than the Sn-Ag solder joint in the case of Au plating of 50nm or less. Cu alloying to the solder promote the formation of (Cu, Ni)6Sn5 instead to Ni3Sn4 as the interfacial reaction layer. The (Cu, Ni)6Sn5 reaction layer can suppress the diffusion of Ni from the N-P plating and thereby inhibit the formation of the P-rich layer. However, in the case of thick Au plating of 250nm or more, a thin P-rich layer formed at the interface even in the Sn-Ag-Cu solder joint and the joint strength was degraded. Au dissolving into the solder from the Au plating during the reflow process may encourage the diffusion of Ni from the Ni-P plating into the solder. As a result, the Sn-Ag-Cu solder joints with 50nm Au coating provided the best joint strength, although its joint strength considerably degraded after the aging treatment at 423K.


2005 ◽  
Vol 502 ◽  
pp. 411-416
Author(s):  
Keisuke Uenishi ◽  
Kojiro F. Kobayashi

The microstructure and strength for the micro joints of Pb free Sn-Ag based solders with Au/Ni alloy platings were investigated. For the joint using Sn-Ag solder, Ni3Sn4 reaction layer formed at the solder/pad interface and also P-rich layer formed in Ni-P plating. The P-rich layer was confirmed to be composed of Ni-P-Sn ternary compound layer and crystallized Ni3P layer. Both of them introduced defects, which degraded the joint strength. Addition of Cu to Sn-Ag solders suppressed the formation of such a P rich layer while the (Cu, Ni)6Sn5 reaction layer was formed at the solder/pad interface. These different interfacial reactions would affect the changes in the joint strength during heat exposure at 423K. On the contrary, addition of Co to Ni platings enhanced the interfacial reaction and the Sn-Ag solder completely transformed to the intermetallic compounds under higher melting temperature even by heating to 543K. The addition of Co in Ni could change the interfacial reaction layer from Ni3Sn4 to (Ni, Co)Sn2 with higher diffusivity of Ni which enhanced formation of intermetallic phases. The control of interfacial reaction by the alloying elements is important to obtain ideal micro joints.


2014 ◽  
Vol 66 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Serkan Büyükdoğan ◽  
Süleyman Gündüz ◽  
Mustafa Türkmen

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; however, a plastically deformed solution-treated alloy has higher strength and wear resistance than undeformed specimens for different ageing times at 180°C. Practical implications – A very useful source of information for industries using or planning to produce Al alloys. Originality/value – This paper fulfils an identified resource need and offers practical help to the industries.


2015 ◽  
Vol 772 ◽  
pp. 250-256 ◽  
Author(s):  
Hideto Harada ◽  
Shin Ichi Nishida ◽  
Mayumi Suzuki ◽  
Hisaki Watari ◽  
T. Haga

This paper describes direct cladding of magnesium (Mg) and aluminum (Al) alloys using a tandem horizontal twin roll caster that has three pairs of upper and lower rolls. Manufacturing conditions that are appropriate for fabricating Al/Mg and Al/Mg/Al cladded material were investigated. The surface condition of the cladded cast strip was examined. An electron probe micro analyzer was used to observe the interface between Al alloy and Mg alloy. The thickness of the mixed layer of Al and Mg alloy was 15μm, and how the materials were connected was clarified. Microscopic observation and backscattered electron analysis were used to investigate the cladding mechanisms of the Al and Mg alloy layers. Average hardness was determined using the Vickers hardness test at the Al layer and at the diffused layer between Mg and Al alloys. Cladding of Al/Mg alloy and A/Mg/Al alloy was possible using a tandem twin-roll caster. In addition, Al3Mg2 and Al12Mg17 phase precipitation at the interface of the Al and Mg alloys was confirmed during direct cladding from molten metals.


Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 727
Author(s):  
Bofang Zhou ◽  
Taohua Li ◽  
Hongxia Zhang ◽  
Junliang Hou

The interface behavior of brazing between Zr-Cu filler metal and SiC ceramic was investigated. Based on the brazing experiment, the formation of brazing interface products was analyzed using OM, SEM, XRD and other methods. The stable chemical potential phase diagram was established to analyze the possible diffusion path of interface elements, and then the growth behavior of the interface reaction layer was studied by establishing relevant models. The results show that the interface reaction between the active element Zr and SiC ceramic is the main reason in the brazing process the interface products are mainly ZrC and Zr2Si and the possible diffusion path of elements in the product formation process is explained. The kinetic equation of interfacial reaction layer growth is established, and the diffusion constant (2.1479 μm·s1/2) and activation energy (42.65 kJ·mol−1) are obtained. The growth kinetics equation of interfacial reaction layer thickness with holding time at different brazing temperatures is obtained.


2005 ◽  
Vol 486-487 ◽  
pp. 125-128 ◽  
Author(s):  
Seong Jong Kim ◽  
Seok Ki Jang ◽  
Jeong Il Kim

The effects of the duration of potentiostatic anodizing on the corrosion resistance and surface morphology of anodic oxide films formed on Mg-Al alloy (AZ91) in 1 M NaOH were investigated. With the formation of an anodic film, the current density decreased gradually, started to stabilize at 300 s, and was relatively constant at 600 s. These results may be related to the increased time for catalysis of the active dissolution reaction, which not only enlarges the area covered by the anodic film, but also produces a more coherent, thicker film. The reference corrosion potentials of the anodic oxide film for AZ91 shifted in the noble direction with time. In general, the corrosion resistance characteristics were improved with anodizing time.


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