Microhardness and Stress Analysis of Laser-Cladded AISI 420 Martensitic Stainless Steel

Effects of Low-Temperature Tempering on Microstructure and Properties of the Laser-Cladded AISI 420 Martensitic Stainless Steel Coating

“…Apparently, both as-cladded and as-tempered specimens consisted mainly of martensite, austenite, and carbides, such as Fe3C. Similar phases have also been observed in laser-deposited martensitic SS coatings [2,6]. The absence of the M23C6 (M represents Cr, Fe etc.)…”

“…By calculating the formulas of Equations (1) and (2), the Cr eq and Ni eq values were 14.6 and 8.87, respectively, as indicated by the red dot in Figure 2a. It is worth mentioning that the 0.55 wt % Ni present in this work, as indicated in Table 1, is higher than those reported in AISI 420 SS with a lean Ni element [2][3][4][5][6][7]. In view of the high hardenability of AISI 420 stainless steel, together with the presence of the austenite stabilizer Ni, it can be reasonably speculated that martensite (M) and austenite (A) coexist in the as-cladded coating in this work.…”

“…However, there was only a little reporting in the literature on laser-cladded AISI 420 SS coatings [3][4][5][6][7]. For instance, Krakhmalev et al [3] investigated the thermal cycling by numerical simulation and the in-situ microstructural evolution by an experiment with AISI 420 SS prepared by a selective laser melting (SLM) technique.…”

“…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 AISI 420/VC metal matrix composites [5]. In order to improve the properties of the laser-cladded AISI 420 SS coating, Alam et al [6] explored the effects of the post-cladding heat treatment (PCHT, 565 • C for 1 h) on the micro-hardness variation and residual stress of laser-cladded specimens. They found that PCHT could lead to not only reductions of micro-hardness and residual stress, but also the precipitation of tempered martensite and more carbides [6].…”

“…In order to improve the properties of the laser-cladded AISI 420 SS coating, Alam et al [6] explored the effects of the post-cladding heat treatment (PCHT, 565 • C for 1 h) on the micro-hardness variation and residual stress of laser-cladded specimens. They found that PCHT could lead to not only reductions of micro-hardness and residual stress, but also the precipitation of tempered martensite and more carbides [6]. Recently, Sun et al [7] reported an in-situ quench and tempering treatment by introducing a laser idle time of 80 s between clad tracks, and demonstrated a significant improvement in the ductility of the AISI 420 SS coating on a 300M steel substrate.…”