Microstructure and Corrosion Resistance of Underwater Laser Cladded Duplex Stainless Steel Coating after Underwater Laser Remelting Processing

Congwei Li,Jialei Zhu,Xian Du,Xiangdong Jiao,Le Mei,Zhihai Cai,Kai Wang

doi:10.3390/ma14174965

Abstract

Combined with the technologies of underwater local dry laser cladding (ULDLC) and underwater local dry laser remelting (ULDLR), a duplex stainless steel (DSS) coating has been made in an underwater environment. The phase composition, microstructure, chemical components and electrochemical corrosion resistance was studied. The results show that after underwater laser remelting, the phase composition of DSS coating remains unchanged and the phase transformation from Widmanstätten austenite + intragranular austenite + (211) ferrite to (110) ferrite occurred. The ULDLR process can improve the corrosion resistance of the underwater local dry laser cladded coating. The corrosion resistance of remelted coating at 3 kW is the best, the corrosion resistance of remelted coating at 1kW and 5kW is similar and the corrosion resistance of (110) ferrite phase is better than grain boundary austenite phase. The ULDLC + ULDLR process can meet the requirements of efficient underwater maintenance, forming quality control and corrosion resistance. It can also be used to repair the surface of S32101 duplex stainless steel in underwater environment.

Highlights

During the long-term service of nuclear power plants, the duplex stainless steel (DSS) plate of the spent fuel pool will have an aging effect
Underwater laser cladding technology has the characteristics of low heat input and high repair accuracy, so it has gradually become an important key technology for the underwater repairs of nuclear power equipment
Researchers have focused on underwater wet laser cladding (UWLC) and local dry underwater laser cladding (LDULC)

Summary

Introduction

During the long-term service of nuclear power plants, the duplex stainless steel (DSS) plate of the spent fuel pool will have an aging effect. In the study of heat treatment and laser surface treatment of DSS, Mohammad M et al [12] found that the retained austenite in the grain of duplex stainless steel transformed into martensite during cold rolling. Alex M. et al [16] studied the laser surface melting treatment of DSS, which resulted in increased surface hardness and decreased corrosion resistance.

Results

Conclusion