Effect of Standoff Distance and Explosive Material Thickness on Properties of Explosively Welded Copper and 304 Stainless Steel

In this research, the effect of standoff distance and explosive material thickness on metallurgical features of explosive welding connection of copper to 304 stainless steel has been investigated. Experimental analysis were performed using optical microscopy, scanning electron microscopy, microhardness test and tensile shear strength test. The results indicated that due to severe plastic deformation in welding, both grain elongation and refinement occurred near the connection. Also, increasing of welding parameters led to an increase in the locally melted zones. The results showed that chemical composition of the melted zone consisted of elements of both flyer and base plates. By decreasing the explosive material thickness and standoff distance, the hardness of copper interface zone decreased from 103.4 HV to 99.8 HV. Moreover, increasing the temperature in stainless steel connection led to decreased hardness. As such, the maximum tensile shear strength of 244 MPa was observed in the sample with 79 mm explosive thickness and 3 mm standoff and the minimum tensile shear strength of about 208 MPa in the sample with 46 mm explosive thickness and 3 mm standoff. By decreasing explosive thickness and standoff, the bond strength decreased, too.