Abstract
Post-treatment is crucial to improve the comprehensive performance of laser-cladded martensitic stainless steel coatings. In this work, a low-temperature tempering treatment (210 °C), for the first time, was performed on the laser-cladded AISI 420 martensitic stainless steel coating. The microstructure and properties of the pre- and post-tempering specimens were carefully investigated by XRD, SEM, TEM, a micro-hardness tester, a universal material testing machine and an electrochemical workstation. The results show that the as-cladded AISI 420 stainless steel coating mainly consisted of martensite, austenite, Fe3C and M23C6 carbides. The phase constituent of the coating remained the same, however, the martensite decomposed into finer tempered martensite with the precipitation of numerous nano-sized Fe3C carbides and reverted austenite in the as-tempered specimen. Moreover, a slight reduction was found in the micro-hardness and tensile strength, while a significant increase in elongation was achieved after tempering. The fractography showed a transition from brittle fracture to ductile fracture accordingly. The as-tempered coating exhibited a striking combination of mechanical properties and corrosion resistance. This work can provide a potential strategy to enhance the overall properties of the laser-deposited Fe-based coating for industrial applications.
Highlights
Laser cladding, as a simple but efficient surface modification technique, has been extensively utilized in different industrial fields such as surface coating functionalization, component repair and additive manufacturing under harsh service conditions [1,2]
Has been considered as one of the potential alloys for creating additive manufacturing functional coatings/components owing to its high mechanical properties, moderate corrosion resistance and tailored properties by the subsequent heat treatment [2,3,4]
Krakhmalev et al [3] investigated the thermal cycling by numerical simulation and the in-situ microstructural evolution by an experiment with AISI 420 stainless steel (SS) prepared by a selective laser melting (SLM) technique
Summary
As a simple but efficient surface modification technique, has been extensively utilized in different industrial fields such as surface coating functionalization, component repair and additive manufacturing under harsh service conditions [1,2]. Has been considered as one of the potential alloys for creating additive manufacturing functional coatings/components owing to its high mechanical properties, moderate corrosion resistance and tailored properties by the subsequent heat treatment [2,3,4]. There was only a little reporting in the literature on laser-cladded AISI 420 SS coatings [3,4,5,6,7]. Zhang et al [4] studied the heat transfer process of the laser-cladded AISI 420 with 4% Mo, and the erosion and corrosion resistance of the laser-cladded.
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