The effect of sintering parameters on diffusion bonding of 316L stainless steel in inserted metal injection molding

Inserted metal injection molding is a unique and new method to produce large-sectioned components. However, what should be taken into consideration in this method is that the bonding of wrought insert to injected outer section is a challenging task. In this study, the effect of sintering temperature, dwell time, and heating rate on diffusion bonding of the insert and injected area, made of 316L stainless steel, has been investigated. Twenty-millimeter components consisting of 60, 70, and 80 % insert/part diameter ratios were fabricated, and the sintering response was investigated by evaluating the shear strength of the bonding zone under varying sintering conditions: sintering temperature ranging from 1260 to 1340 °C; dwell time of 30, 60, and 90 min; and heating rates of 1.5, 3, and 4.5°K min−1. It was shown that shear strength of the bonding zone could be up to 342 MPa depending on insert/part diameter ratio and sintering condition. It was also proven by ANOVA that among sintering parameters, sintering temperature is the most effective one compared with dwell time and heating rate. In addition to shear-punch test, microhardness as well as SEM views were carried out to study the bonding zone with more details.