Investigating the Effect of Strain and Rolling Temperature on the Microstructure and Hardness of Explosively Bonded Copper-304 Stainless Steel Plates

In this research, the effect of the amount of strain and rolling temperature on the microstructure and the hardness of the explosively bonded 304 stainless steel- copper sheets were investigated. Explosive welding was performed using two explosive thickness of 46 and 79 mm with a stand-off distance of 2 and 3 mm. The results of the optical microscope after welding showed that all samples had a common wavy interface. The results of scanning electron microscopy and EDS analysis showed that in all samples the melting region was observed in the joint. The results of micro-hardness tests showed that the most hardness in interface was the sample with the highest thickness of the explosive and the stand-off distance. Rolling operations were carried out with a thickness reduction of 2 mm in two different conditions without preheating and preheating at 300 ℃ and 30 minutes. The results of the optical microscopy after rolling showed that in all cases after rolling, a decrease in the amplitude of the waves (wavelength thickness) was created. The results of the scanning electron microscopy and EDS analysis in the post-rolling and pre-heat conditions indicated that as a result of pre-heat before rolling operation, the copper and iron elements diffused from the interface of copper melting-metal region. Investigating the results of post-rolling non-treating samples showed that hardness after rolling in all samples increased. But in pre-heated samples, the hardness was less than that of as-welded samples.