Laser-cladding and interface evolutions of inconel 625 alloy on low alloy steel substrate upon heat and chemical treatments

SURFACE & COATINGS TECHNOLOGY

卷:404

Article

Liu, Hongfei¹  Tan, Chee Kiang Ivan¹  Wei, Yuefan²  Lim, Suo Hon¹  Lee, Coryl J. J.¹ 

[1] ASTAR, Inst Mat Res & Engn IMRE, 2 Fusionopolis Way, Singapore 138634, Singapore

[2] ASTAR, Adv Remfg & Technol Ctr ARTC, 3 Cleantech Loop, Singapore 637143, Singapore

关键词: Laser-cladding;    Inconel 625;    Heat treatment;    Hot corrosion;    Molten salts;    Chemical etching;    Heat-affected zone;    Interface strains;   

DOI  :  10.1016/j.surfcoat.2020.126607

来源: Elsevier

【 摘 要 】

Dual-layer structures of inconel 625 (In625) alloy have been deposited by laser-cladding on low alloy steel substrates for corrosion protections at elevated temperatures. Structural and morphological characterizations, before and after treatments in molten salts and/or acidic solutions, reveal absence of corrosions of the In625 layer except for a similar to 2-mu m-thick Cr2O3 layer formed on its surface. However, the heat treatments give rise to remarkable delta-Ni3Nb precipitations along with an in-plane lattice shrinkage [i.e., epsilon(gamma(111)) = -0.26%] of the In625 layer; the former are replaced by carbides (i.e., M3C/M23C6) while the latter is increased to epsilon(gamma(111)) = -0.66% when approaching the In625/MS interface. Chemical treatments reveal a much faster material removal from the heat affected zone (HAZ), R-HAZ, than those from the base material of the substrate, Rs. They also reveal an inplane lattice expansion [i.e., epsilon(gamma(111)) = 0.31%] of the In625 layer near the interface along with the material removal. In comparison, after the heat treatment, R-HAZ became smaller than R-S and, meanwhile, the shrunken inplane lattices do not exhibit any expansions upon the chemical etching. These observations provide evidence that both the carbide precipitations and the local strains play an important role in the interface stability of the laser-cladded In625/Steel structures upon heat and/or chemical corrosions.

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