Influence of synchronized rolling-assisted process on crack and properties of Ni-WC laser cladding layers

To investigate the process method to inhibit the cracking of the laser cladding layer, based on the concept of synchronized micro-forging, this paper applies a self-developed laser cladding synchronized rolling auxiliary device to prepare Ni60-WC cladding layer by laser cladding on the surface of Q235 steel substrate. An optical microscope, scanning electron microscope, Vickers microhardness tester, X-ray diffractometer, friction and wear tester, and three-dimensional optical profilometer were used to observe, test, and analyze the macroscopic morphology, microstructure, physical phase composition, microhardness and wear-resistant properties of the fused cladding layer. This paper focuses on comparing the observation of cracking defects with and without the application of a synchronized rolling-assisted device to prepare the cladding layer and analyzes the reasons for the different results. The results show that: the synchronized rolling auxiliary process can effectively inhibit the generation of cracks, synchronized roller in the synchronized rolling device, under the action of high laser power, produces the effect of a secondary heat source, which has the effect of heating and heat preservation on the fusion cladding layer, reduces the temperature gradient of the fusion cladding layer when it is cooled, and the accumulation of thermal stress is reduced. In the synchronized rolling process, the molten cladding layer is in the dynamic response to the recrystallization stage, the growth time of the grain is relatively longer, the grain size increases slightly, the hardness decreases slightly, but the plasticity and toughness increases, the amount of wear is reduced, and the wear resistance is improved.