Process characterization in laser metal deposition of EN AC-43000

Abstract

EN AC-43000 is a well-established cast material for the production of parts, which are used in the automotive and optical industries. Typical components like cylinder heads, control blocks for automatic transmissions, or housing are manufactured via die or sand casting. The casting process depends on a lot of influencing parameters and is difficult to control. Reject rates up to 10% are the consequence. Those parts are mostly characterized by defects like pores, blowholes, or surface deviations. Such defects restrict the functionality of the component, especially if they are located next to sealing surfaces or at mechanically or thermally high strained areas. In general, defect components are recycled by putting them back to the melt feeding of the casting process. An alternate approach in the presented paper is the repair of the defect components via powder-based laser metal deposition (LMD). EN AC-43000 represents a group of aluminum alloys that are characterized by a restricted weldability. Difficult material properties like the affinity to oxygen and the high thermal diffusivity cause porosity and high dilution. Welding experiments are performed using a disc laser with a maximum output power of 4 kW. The typical seam parameters, such as width, height, depth, and cross-sectional area, are measured in order to characterize the LMD process and to define process limits. Furthermore, the ways to optimize dilution and porosity are presented.