Exploration and Analysis of Strain Softening Phenomena of L6 Steel

Abstract

It is a necessity of modern forging industries to explore new materials for hot forging dies, which gives better quality of forging with extended fatigue life and less economic aspects. L6 Steel is one of the material for modern metal forming industries, which mollifies all the benchmarks and requirements. PreMature fatigue failure of forging dies is always an unpredictable and economical damage for any metal forming industry. L6 Steel is a high strength material to avoid die cracking during complex phenomenon of hot forming process. L6 steel, which when subjected to load, will get softened and this is strain softening. In this paper, numerous experiments have been carried on L6 steel material to evaluate cyclic Stress-strain behavior of this material. This research leads us to evaluate and explain phenomenon regarding strain softening and its behavior during low cycle fatigue test. Low cycle fatigue test is carried out on MTS fatigue test machine at fully reverse loading condition R=-1. Also strain softening effect on forging metal forming process is explained in detail. The failed samples during low cycle fatigue test further investigated metallurgically on scanning electron microscopy. Material micro mechanisms further investigated by EBSD technique. Finally the study concludes that, strain softening phenomenon plays a vital role in the fatigue failure of metal forming dies.