Control of dilution during laser cladding of Al7075 substrates with Al-12Si aluminium alloy powder

The feasibility of controlling dilution through on-line temperature control during continuous wave laser cladding of aluminium (Al) alloys has been investigated. A series of experiments was conducted at IRIS with a high power Nd:YAG laser using Al 7075-T6 substrates and an Al alloy powder containing 12wt% silicon (Al-12Si). The melt pool temperature was measured with a 2-colour optical pyrometer and on-line temperature control was performed by closed loop monitoring of the laser power using the TemCon^© control software developed at LZH. Comparative cladding trials were performed with and without temperature control, as well as with and without cooling of the substrate. The effects of laser cladding condit ions such as the substrate scan rate, powder feed rate and track increment on clad dilution were determined by quantitative metallography. Results are described in this paper and the benefits of on-line temperature control are discussed.