Master of Science, The Ohio State University, 2020, Welding Engineering

High pressure die casting is used to quickly and repeatably manufacture high volumes of aluminum parts with good surface finish. Thermal fatigue cracking (heat checking) from thousands of thermal cycles, local soldering of aluminum part features to the surface, and buildup of lubricant residue leads to damage of die surfaces. Manual repair of hot work tool steel (HWTS) dies using arc welding is burdensome, involving high preheats and post weld heat treatment (PWHT) to restore HWTS properties. Improved automated repair procedures and materials are necessary to reduce die casting costs. This effort focused on developing automated arc welding repair procedures, characterizing clad deposit microstructure, evaluating tempering effects in the H13 heat affected zone (HAZ), and cladding shot block dies for in-plant trials using an experimental Anviloy (W-27.5Ni-12.5Fe) alloy wire on H13 HWTS dies. Mechanized hot wire gas tungsten arc welding (HW-GTAW) procedures were developed to produce low dilution single and double layer deposits. The minimum weld dilution with HW-GTAW required to produce sound clads was 18%. HW-GTAW trials showed that consistent, sound Anviloy wire clads could be deposited onto H13 using arc welding. Robotic gas metal arc welding pulse (GMAW-P) procedures were developed for conformal cladding the shot block. The robotic GMAW-P system provided better accessibility to accommodate shot block features. Both a DC+ and DC- advanced waveform were evaluated, but only the DC- waveform resulted in stable and sound deposition of Anviloy wire consumable. The die block's complex shape mandated the use of sub-optimal torch angles when cladding in the 2G position. Work angle oscillation was used to improve bead shape in these adverse torch positions. A weld stop procedure was developed to improve conformal cladding complex shapes. The developed two layer cladding procedure minimized number of weld passes and amount of deposited material needed to create a 10mm clad l (open full item for complete abstract)

Committee: Dennis Harwig (Advisor); Boyd Panton (Committee Member) Subjects: Engineering; Materials Science; Metallurgy