Structure and Properties of the Wear-Resistant Coatings Fused on Steel with Flux Cored Wires by an Electric Arc Method

The structural–phase states and mechanical properties of the coatings fused on Hardox 400 (0.18 С; 0.7 Si; 1.6 Mn) martensite steel with welding wires of 1.6 mm diameter and different chemical compositions EnDOtec DO∗33 (2.06 C; 0.6 Si; 2.51 Mn; 13.5 Cr; 6.4 Nb), EnDOtec DO∗30 (0.5 C; 0.4 Si; 1.4 Mn; 1 Cr), and SK A 70-G (2.6 C; 0.6 Si; 1.7 Mn; 2.2 B; 14.8 Cr; 4.7 Nb) are studied using the methods of optical, transmission and scanning electron microscopies, x-ray structural analysis, measurements of microhardness, wear resistance, and friction coefficient. The forming of deposit welding on the steel surface is accompanied with the formation of multilayer structure with different morphology of substructure elements. The deposit welding bulk is characterized by the micropore and microcrack presence that indicates the elastically stressed material state. The sources of the cracks appear due to the large inclusions of the second phase and crystallization dendrites. It is demonstrated that the coatings have much higher microhardness (by 2–3 times) and wear resistance (by 2 times) than the substrate has, while the friction coefficient is 1.2 times lower as compared with that for the substrate; the microhardness of fused coating is a constant along the whole depth up to 4.0 mm. The strengthening is caused by the formation of submicrosize and nanosize structures containing particles of the second phase (Fe3C, Fe23(CB)6, NbC, (FeSi)3B, Cr3C2, Fe3B, and Fe3Si0,97). Their volume content reaches 40%.