Failure Analysis of HSS Punch Tool: A Case Study
The work reports the failure investigations of HSS M35 grade steel that is used as a punch tool during cold forging process. The test samples were prepared from the heat-treated tool material and studied for composition, hardness, retained austenite, and microstructure. The punch tool operates at 800 MT during cold forging. It had produced 800 nos. of forged components before its failure. It is observed from the results that composition, hardness, and microstructure are conforming to the standard HSS M35 grade tool steel. The retained austenite (RA) percentage of the tool is within the acceptable limits. Fractographic studies were conducted on the failed sample using scanning electron microscope (SEM) to examine the fractured features. The cause of failure has been arrived at based on the fractographic analysis as well as macro-visual inspection of the fixture that is employed to clamp the punch tool. It is observed that, at the inner portion of the fixture, the presence of small pits and rubbing marks/ridges has caused stress concentration zone, leading to breakage/failure.
KeywordsPunch tool Cold forging Fractography Fatigue failure Failure investigation
The authors would like to thank the management of Sambhram Institute of Technology, Essae Digitronics Pvt. Ltd., and Central Power Research Institute for having accorded permissions to present the paper.
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