A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅱ) - Mechanism of Dissimilar Metal Joining -

Abstract

As a result of studying the research trends of dissimilar metal joining using the arc heat source, the process parameters that determine the quality of the joints can be classified into the filler metal, type of coating, heat input energy and joint conditions such as the gap. Among these parameters, the joining mechanism has already been identified by many researchers from the metallurgical point of view such as the kind of the filler and the characteristics according to the heat input. Therefore, in this study, we tried to understand the joining mechanism related to kind of coating and wettability through high speed camera observation. We also studied the effect of not only the various coating but also the thickness of coating layer. As a result, there was a large difference in bonding property depend on the type of coating in the joint. In case of galva-annealed steel, the coating layer was not sufficiently melted due to a higher melting point compare with galvanized steel, so that a large amount of spatter was generated and no wetting occurred under any conditions. Also we cannot found the relationship between the thickness of the coating layer and the generation of the intermetallic compound. However, the difference about the quality of the joints is evident because the amount of Zn vaporized under the same heat input condition is increased.

Joint Properties of Aluminum Alloy and Galvanized Steel by AC Pulse MIG Braze Welding

“…bead surface is generated [3]. The size of the pin hole decreased with the EN ratio, corresponding to a higher heat input.…”

“…Generally, the porosity influencing joint properties can be divided into three types: pin hole, blow hole, and worm hole. If the solidification rate is faster than the growth rate of porosity, a very small pin hole in the bead surface is generated [3]. The size of the pin hole decreased with the EN ratio, corresponding to a higher heat input.…”

“…As shown in Figure 7a-c, from the results of the composition analysis, Zn ranging from 8.85 to 1.27 wt.% was detected in the bottom area, but the pores distributed in the matrix did not have Zn, as shown in Figure 7d. Hence, pores caused by hydrogen could be easily formed because the hydrogen porosity during solidification gave liquid Al the ability to absorb a large amount of hydrogen [3]. As a result, the crack initiated at the end of thin pin holes and then it propagated along the finer pores, finally leading to a fracture perpendicular to the tensile loading direction.…”

Recent Joining Techniques of CFRP to Metal Using Welding Process

“…용접 19) 과 함께 아크 열원을 이용한 브레이징 접합 [20][21] 등 [24][25][26][27][28] , 초음파용접 [29][30][31][32] , 마찰교반용 접 [33][34][35][36] 및 마찰교반점용접 [37][38][39][40]…”