Effect of Fracture Morphology of Oxide Film in Solid-phase Forge Welding

―Solid-phase Forge Welding of Dissimilar Metals Ⅰ―

Abstract

Solid-phase forge welding (SPFW) is an effective method for bonding dissimilar metals in bulk. However, the bonding parameters for achieving strong and stable bonding by SPFW are not clarified. To investigate the parameters, a new test method to evaluate SPFW was developed. Using this method, we prepared test pieces bonded with SUS304/A1070 with various surface enlarging ratios and surface pressures on the interface. Tension tests were performed to measure bonding strength. It was found that strong bonding was obtained in specimens exceeding the surface enlarging ratio = 3.0, the surface pressure = 1740 MPa. After the tension tests, SUS304 fracture surfaces were observed by electron microscope. As a result, it was found that the SUS304 fracture surface was divided into the oxide film area and the exposed virgin area. In addition, oxide films were cracked after the surface enlargement, and A1070 adhesion was observed only on the virgin area, which was exposed in the gap of oxide films.