The Effect of Stand-Off Distance on the Structure and Properties of Zirconium – Carbon Steel Bimetal Produced by Explosion Welding / Wpływ Odległości Blach Na Strukturę I Własności Bimetalu Cyrkon - Stal Wytworzonego Technologią Zgrzewania Wybuchowego
This study focuses on the effect of the stand-off distance between the bonded plates on the properties of zirconium (Zr700) - steel (P355NL2) bimetal produced by explosion welding.
Bonding trials were carried out in parallel arrangement at constant detonation velocity. The analyses of microstructural transformations occurring in the bond zone and mechanical properties of the clad were performed for as-bonded welds, i.e. immediately following explosion welding. A general description of the obtained welds was made (height and length of the wave was determined) and the quantitative fraction of the melt zones was calculated along the bond’s length. Using optical microscopy and scanning electron microscopy (SEM) enabled the assessment of the quality of the formed bonds, initial identification of phases and quantitative analysis of the individual phases on the longitudinal section. The microhardness results were used in the analysis of hardening changes at the interface area.
The completed research proves the potential to obtain a proper bond for zirconium/carbon steel sheets. A strong effect of the stand-off distance on the strength properties of the fabricated plates was observed, and the ’direction’ of these transformations was pointed out. Optical microscopy and SEM examinations allowed determining the characteristic of the bond interface for diverse stand-off distances. It was established that increasing the stand-off distance between the plates causes the reduction of the melt area along the length of the bond, which improves strength properties of the bimetal. The analysis of the strength distribution performed based on the microhardness measurements showed that the changes occur within the distances up to 500µm from the bond interface and the highest hardening, for both zirconium and steel, is directly at the interface and then successively decreases.