Thermal and Structural Characterization of Copper–Steel Bonding Interfaces Produced by Impact Welding

Abstract

A complete characterization of Cu–steel impact welded were made using photothermal radiometric (PTR) spectroscopy, scanning electron microscopy (SEM), microhardness, and X-ray diffraction (XRD) in order to study the changes in the structural, metallurgical, and thermal properties of Impact Welding Zone (IWZ) and the Impact Affected Zone (IAZ) after the impact welding. Three samples with different morphological interfaces were prepared for this analysis. According to the SEM analysis in etched samples, it was possible to determine that the IWZ is formed by the collapse of grains of Cu and steel (ferrite and pearlite) into the Cu–steel interface and the IAZ are formed in a region close to the IWZ with low grain damage. Microhardness Vickers test is able to detect the IAZ in all cases, but due to its contact character, it is not possible to obtain continuous hardness information across the Cu–steel interface. According to the XRD patterns after the impact welding process, no new phase was formed. Noncontact PTR amplitude and phase images are able to identify the IAZ and the IWZ.