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 automotive and optical industry. 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 percent are the consequence. Those parts are mostly characterized by defects like pores, blowholes or surface deviations. Such defects are restricting 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 put them back to the melt feeding of the casting process. An alternative approach in the presented paper is the repair of the defect components via powder based laser metal deposition. EN AC-43000 represents a group of aluminum alloys which are characterized by a restricted weldability. Difficult material properties like the affinity to oxygen and the high thermal diffusivity, are causing 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 laser metal deposition process and to define process limits. Furthermore, ways to optimize dilution and porosity are presented.