May 2023 Volume 5

FORGING RESEARCH

Final Report: Evaluation of Rejuvenated Forging Tools Supported Staff: JimMcGuffin-Cawley, Case Western Reserve University Department of Materials Science and Engineering Industry Collaborators: Presrite Corporation Carl Taslma, Corporate Metallurgist John Deighton, Plant Manager Lincoln Electric Company Kyle Smith, Business Manager, Automation Christopher Agosti, Laser Applications Engineer

Executive Summary This Stage-Gate FIERF Research grant began with an objective of resurfacing a production forging die using laser-hot wire welding followed by in-plant trials with the resultant resurfaced die.This was motivated by the positive results of a prior Defense Logistics Agency sponsored program on AM die repair, and calculations suggesting an economically favorable “infinite” resurfacing of 718 nickel alloy tooling. Laser hot-wire was explored since it is much lower net heat-input than arc welding, and thus offers the possibility of high deposition rate and modest heat-affected zones. However, toolpaths and optimization of deposition parameters proved difficult and, due to the long timeframe associated with each iteration, it was not possible to obtain weld overlays with a low enough defect density to permit the desired in-plant trials. The project was then redirected at bringing on-line a gantry-based freeform welder created through integration of a plasma cutting table (4 ft x 4 ft x 0.5 ft) and a MIG welder. This freeformwelder will be used for future student projects. Background Under support from the Defense Logistics Agency, research in the Department of Materials Science and Engineering examined the prospect of systematically rejuvenating, and improving, the working surface of forging tooling. This was a five year project that employed an array of welding-based and additive manufacturing methods to the repair of forging dies through close collaboration of forgers and researchers. The collaboration at its best provided significant die life extension, lower costs, shorter lead times, and reduced scrap generation (both in die fabrication and in fewer scrapped parts).

The greatest success was achieved using wire-fed systems with either arc or laser heat sources for deposition. Less success was observed when powder-fed laser depositions were attempted, likely due to limited available effort to identify an appropriate processing window(s). The most outstanding results were observed at BAE Systems and Modern Forge. A tank track die from BAE Systems that previously had a practical service life of 3,500 to 4,000 parts per die, was extended to more than 13,000 after re-sinking and cladding with Stellite 21LA. A Buster ‘R’ die from Modern Forge typically produced about 20,000 parts before re-sinking. After cladding with Waspaloy, the Buster ‘R’ die produced more than 113,000 parts. These are two of several examples of success with composite cladding, i.e., cladding materials that were very different than the underlying substrate. These outstanding improvements were obtained by Absolute Welding, Inc. using a robotic arc-welding system that was developed by NeWeld (Italy) and sold in the US by Eureka Welding Alloys (Michigan). Not all cladding attempts were successful, resulting in a range of performance outcomes throughout the project. Lack of success has been linked to specific defects formed during claddingmanufacture. For example, thick cladding layers resulted in significant residual stresses, which degraded the ability to form the desired die surface (either through inability to EDM the surface or due to warpage). Lack-of-fusion defects during cladding deposition also contributed to difficulty in subsequent die preparation. In the most successful parts of this project, stringent process control was identified to be a key factor.

FIA MAGAZINE | MAY 2023 85