Accelerated Fatigue Testing of High‐Speed Steel

ABSTRACT The staircase method is commonly employed in the characterization of metals to determine their fatigue limit. In this approach, the stress amplitude is systematically varied around the assumed fatigue limit in consecutive tests. However, its applicability for in‐process optimization in alloy design and development is limited by the large number of specimens required—particularly for high‐speed steels (HSSs), which exhibit pronounced scatter in fatigue limit—resulting in long testing times. To address this limitation, accelerated fatigue testing is applied to HSS for the first time in the present study. The stress amplitude is continuously increased within a single experiment while recording the specimen temperature, enabling the fatigue limit to be estimated from the dissipated energy of a single specimen and thereby reducing both material consumption and testing time. The applicability of the accelerated fatigue testing method is demonstrated for an ingot‐cast HSS (AISI M2) and a powder‐metallurgical (PM) HSS (AISI M3 Class 2) fabricated by hot isostatic pressing (HIP) as consolidation technique. In addition, the fatigue limits of both materials are determined using the conventional staircase method at various highly loaded volumes (HLVs) to characterize the defect distribution and to validate the results obtained from accelerated testing.