DEBACOAT project: Effect of pre-heating temperature on microstructure and wear resistance of a laser cladded Ni-based alloy reinforced with tungsten carbides

摘要

Laser cladding (LC) is one possible deposition technique suitable for producing dense hardfacing alloys. Thick deposits produced by laser cladding with WC-reinforced Ni-based alloys represent optimal wear-resistant materials for components subjected to service under severe abrasive environments. One of the main concerns of this technique when used with hard materials is crack susceptibility during the deposition. This issue is controlled by proper alloy selection, by opportune cladding parameter design and by pre-heating of the substrate to reduce residual stress accumulation. In this research, different pre-heating levels were adopted in order to check the crack formation in a WC/Ni-based alloy. In correspondence of a pre-heating temperature of 550°C no cracks were identified in the deposits. Partial dissolution of WC-W_2C carbides was observed, inducing the formation of rod-like W-Cr rich carbides at the interface with the Ni-Cr matrix. The Ni-based alloy reinforced by WC showed an improvement of about 15% in hardness and an improvement of about 90% in wear resistance under pin-on-disc test conditions, compared to the matrix.