Optimizing direct laser metal deposition of H13 cladding on CuBe alloy substrate

This work aims at depositing single-layer H13 tool steel cladding on a precipitation hardening copper‑beryllium (CuBe) alloy substrate using direct laser metal deposition (DLMD). The process parameters, i.e. laser power, powder feed rate, overlap ratio, and substrate temperature were optimized at the scan speed of 1000 mm/min for both single-track and single-layer cladding. The clad quality was evaluated according to i) geometrical features ii) cladding defects, iii) interfacial adhesion, and iv) substrate over-aging. The energy-mass balance was sensitive to the variation of processing parameters especially when the high reflectivity CuBe substrate was used. The dense and sound cladding was eventually deposited after parameter optimization. Substrate preheating inhibited crack formation. However, the higher the preheating temperature, the larger the substrate softening due to over-aging: using 150 ◦C, the substrate hardness decreased by 13% down to 2.7 mm in depth, while at 250 ◦C it decreased by 40% down to the same depth. The single-layer H13 clad layer produced at a 150 ◦C-preheating temperature showed a better load-bearing capability than CuBe alloy substrate, up to 20 kN indentation load. Meanwhile, its surface hardness and wear resistance were remarkably higher.