Adhesive joint strength of dissimilar metal adherends by Taguchi Method

Abstract

The dissimilar metal joints are widely used in many applications. A lot of efforts have been made to study the joining techniques in order to achieve a reliable dissimilar joint for unlike metals including welding. However, dissimilar welding methods is facing critical failure because of the differences in thermal expansion between the different metals. This research is concerned with the investigation of joining dissimilar metal between stainless steel and carbon steel by adhesive joining technique. Adhesive bonding has the advantage and ability to joint different types of material. The main purpose of this study is to investigate the effect of heat treatment on medium carbon steel (AISI 1045) and stainless steel (AISI 304) and its effect on adhesive bonding strength. An experimental approach has been made to attain the research purpose with respects to these factors; adherend mechanical properties, surface treatment and adhesive thickness. The mechanical properties were controlled by using several heat treatment processes, annealing for stainless steel whilst annealing, normalizing, and quenching was done on carbon steel. Surface treatment was controlled by using sandpaper at 180, 500, and 1000 grit. Lastly, an alignment jig was used to control the joint geometry to have an aligned butt-joint specimen and to have a 0.5mm, 1.0mm, and 1.5mm adhesive thickness. The adhesive used in this investigation is Araldite, a slow-setting epoxy adhesive; it consists of two components which are resin and hardener manufactured by Huntsman Corporation and the specimens were divided into three groups which were named as as-received (AR), sequence 1 (SQ1) and sequence 2 (SQ2). Each group has nine numbers of experiments which were carried out by using Taguchi Method. Three specimens were prepared for each experimental condition. A total of 81 tensile tests at room temperature have been carried out under axial tensile test by Universal Testing Machine (UTM). Signal-to-noise ratio (SNR) and analysis of variance (ANOVA) analysis was used to find the optimal parameter setting resulting the highest tensile strength of adhesive bonded butt-joint specimen. Other tests were also done on adherend which are surface roughness and visual examination to find the relation or underlying reason for the analysis results. Based on ANOVA results, it was found that the contribution of adhesive thickness is 59.38%, which is higher than abrasive paper, 28.76% for AR group. For SQ1 group, the factors influencing the tensile strength in descending order are abrasive paper, 26.09% followed by adhesive thickness and heat treatment with 24.12% and 12.71% respectively. While the main factors influencing the tensile strength in SQ2 are adhesive thickness 67.51%, followed by the abrasive paper with 12.80% and then heat treatment 11.00%. This result shows that the heat treatment process have insignificant influence on adhesive butt-joint strength of AISI 1045 and AISI 304.