STRUCTURES OF GRADIENT LAYERS OBTAINED USING THE LASER METAL DEPOSITION (LMD) METHOD

Abstract

The paper presents the results of structural investigations of a laser-welded layer in the Inconel 625 and Stellite 6 alloy matrix with the addition of WC. The tests involved the use of on plates made of low-alloy steel S355J2C+N. The filler materials used in the tests were nickel-based (Inconel 625) or co-balt-based powders (Stellite 6) having various contents (0-25%) of spherical tung-sten carbide (WC) used as the reinforcing phase. The granularity of the powders was re-stricted within the range of 45 µm to 90 µm. The cladding tests involved making multi-layer overlay welds. Next, non-destructive (VT and PT) and destructive (macro, hardness) tests were carried out. The macroscopic metallographic tests revealed that the three-layer Inconel 625-based overlay welds (with a WC content of up to 15%) had the correct shape and were characterized by full fusion into the base material, ensuring the continuity of the overlay weld.In the case of the Stellite 6-based overlay welds containing 10% of WC, it was possible to observe a through-crack of the overlay welds. The crack was formed in the first layer (as a result of stresses during the solidification of the liquid metal) and developed during the deposition of subsequent layers. The macrostructural tests were supplemented with microstructural observations and microanalysis of the chemical composition (EDS). The above-named tests revealed the good stirring of alloying elements in the overlay weld, indicating the high homogeneity of the overlay weld.The hardness obtained on the surface of the padding weld was 600 HV1.