Structure and low-cycle fatigue of steel AISI 316 after ECAP

Purpose: Main aim of this paper is to describe the plastic deformation executed by ECAP on low cycle fatigue of steel AISI 316. Among others was attention fixed on mechanical properties after this treatment. Design/methodology/approach: Experiments were planned and realised at the temperature ranging from room temperature up to 280 °C. After application of deformation the structure was investigated in dependence on accumulation of deformation and deformation temperature as well as abovementioned final properties. Findings: Accumulated real (logarithmic) deformation varied from the value 2 to 8. Investigation of structure by electron microscopy was made with use of microscope JEOL JEM 2100. Mechanical properties were investigated by conventional tensile test and penetration test. Selected samples were subjected to low-cycle fatigue. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD) in combination with scanning electron microscope FEG SEM Philips. Practical implications: The Technology ECAP was applied on austenitic steel AISI 316. It was verification of ECAP application possibility on steel AISI 316 importantly for following applying on similar kinds of steel, because ECap technology influence on fatigue properties was confirmed. Originality/value: It can be predicted on the basis of obtained results that, contrary to low-cycle fatigue the ultra-fine grained material will manifest at fatigue load in the mode of constant amplitude of stress higher fatigue characteristics, particularly fatigue limit.