The effect of heat treatment on the properties of zirconium - Carbon steel bimetal produced by explosion welding

Abstract

This paper assesses the effect of the heat treatment on the mechanical properties and the structure of the bond zone in zirconium (Zr 700) - steel (P355NL2) bimetal. The investigations were performed for welds with varied characteristics of the bond zone. Experimental results were presented concerning the strength tests (the values of peeling - Ro, shear - Rs and tensile Rm strength), measurement of hardness, and structural analyses carried out in micro- and macro-scale. Microhardness measurements shows that the increase in the detonation velocity during explosion welding causes the increased share of the melted area in the bond, the increase of the deformed area and consequently hardening at the interface. Applying heat treatment lowers the hardening in the bond zone, which is more pronounced in the base material, i.e. steel. This effect results from the full recrystallization of the grains in the plastic deformation area. The selection of temperature is paramount as the higher the temperature, the lower tensile resistance of the bond zone. Applying the same settings for materials with different characteristics showed the treatment did not considerably influence the shear strength, but significantly affects tensile and peeling strength.