Laser cladding and in-situ nitriding of martensitic stainless steel coating with striking performance

The nitrogen (N) alloying in traditional bulk martensitic stainless steel (MSS) necessitates high-pressure and high-temperature treatment because of its extremely low solubility. Herein, we report a novel strategy for in situ nitriding MSS coating with N content up to 0.14 wt% by laser cladding technique without harsh conditions. The resulting coating is composed of martensite, austenite, nano-precipitates M23C6 and M2N, which exhibits striking mechanical properties with tensile strength of 1900 MPa and elongation of 7.3% as well as excellent corrosion resistance, exceptionally superior to the reported laser cladded MSS coatings. This may be ascribed to the combination impacts of grain refinement, nano-precipitation, interstitial solid solution and dislocation strengthening. (C) 2019 Elsevier B.V. All rights reserved.