Effect of different overlap cladding transition layer – Austenitic stainless steel coating and defect degree on corrosion resistance.

The effects of overlap rate and defects on the corrosion resistance of laser fusion clad austenitic stainless steel coatings were studied. In this paper, the Ni transition layer and Fe-based coating were sequentially prepared on grey cast iron, and the corrosion morphology and corrosion mechanism of the coating were comprehensively analyzed through physical phase, microstructure and electrochemical tests. The coating phase was mainly γ-Fe, which formed strong selective orientation and texture strength at the (100) crystal plane; overlap ratio and defects affected the recrystallization changes, and the stresses near the defects were high. Increased overlap rate (Fe-based alloy 50 % → 66.7 %) could result in microstructure refinement, reduced corrosion rate v (A8 6.22×10−4 g/m2·h→A9 3.12×10−5 g/m2·h), and improved corrosion resistance. Corrosion cracking extended the crack and embrittled the alloy at the tips of the cracks, so that its (|Z| max 0.67 ∼ 1.31×104 Ω cm2) influence on the corrosion resistance was much higher than that of the pore (|Z| max 5.85 ∼ 10.2×104 Ω cm2). The best corrosion resistance of the process was achieved with an overlap ratio of 66.7 % for both the Ni transition layer and the Fe-based coating. • Different laser overlap cladding manufactured transition layer – Fe-based coating. • Defect characteristics and change mechanisms were analyzed. • Overlap rate and defects on corrosion resistance of coating mechanism were analyzed. [ABSTRACT FROM AUTHOR]