2.1. Materials Fabrication

The 2Cr13 steel (corresponding to 420 steel, US ASTM Standards) with a dimension of 150 mm × 150 mm × 10 mm was used to the substrate, its chemical compositions are 0.22 wt.% C, 12.9 wt.% Cr, 0.4 wt.% Si, 0,61 wt.% Mn, 0.016 wt.% S, 0.018 P wt.%, and the balance Fe. The microstructure of the 2Cr13 substrate is mainly composed of the α-Fe matrix and the M₂₃C₆ carbides distributed along the grain boundaries, as shown in Figure 1. The 2Cr13 substrate was grinded using the 1000# SiC sandpaper, and then cleaned by alcohol and acetone. High aluminum and chromium Fe-B-C powder was proportioned with pure alloy powder with a size of 60–80 μm. The prepared high aluminum and chromium Fe-B-C powder was dried in a drying oven to remove moisture, and then put into a ball mill pot in a glove box and ground at 120 r/min for 4 h. The chemical compositions of high aluminum and chromium Fe-B-C powder after mixing were measured by inductively coupled plasma mass spectrometry (ICP-MS), as shown in Table 1.

The microstructure image of the 2Cr13 steel substrate.

The chemical compositions of the high aluminum and chromium Fe-B-C cladding powder (wt.%).

In this study, IPG-6000 optical fiber laser cladding system was used for laser cladding. First, a layer of high aluminum and chromium Fe-B-C powder with a thickness of 1 mm was prefabricated on 2Cr13 steel plate. The binder was cellulose acetate (C₆H₈O₃ (COOCH₃)₂)_n. Before laser cladding, the 2Cr13 substrate was preheated to 80 °C to reduce cracking. The main parameters are 2.5 kW laser power, 4 mm/s scanning speed, 15 L/min-Ar gas flow speed, and 5 mm × 5 mm spot size. The metallographic sample with a size of 10 mm × 10 mm × 5 mm was prepared by wire cutting. After grinding and polishing, it was cleaned using acetone and alcohol for 60 s.