The influence of rolling process on fatigue properties of 316L/ 2Cr13 multilayered steel and analysis of its fracture process

In order to investigate the effect of the rolling process on the fatigue properties of 316L/2Cr13 Multilayered Steel (MLS), high-cycle fatigue tests of MLS at a stress ratio of 0.1 are performed on the universal testing machine. The MLS composed of the austenitic stainless steel 316L and martensitic stainless steel 2Cr13 is prepared by accumulative roll-bonding (ARB). Furthermore, MLS is prepared under a variety of rolling temperatures and rolling sequences. The changes of microstructure and properties as well as fracture mechanism are analyzed by means of Scanning Electron Microscope (SEM), Electron Back Scatter Diffraction (EBSD), tensile tests, fatigue tests and interruption tests. The results reveal that in contrast to the full martensite and full austenitic MLS, the fatigue properties of 316L/2Cr13 MLS are improved. When the rolling process is "1130 degrees C 4 + 6 passes" and "1200 degrees C 10 passes", the MLS possesses the optimal performance. In addition, the fatigue strength of MLS first increases and then decreases with the increase of tensile strength. Interruption test shows that the fatigue crack of multilayered steel starts from ferrite phase of 2Cr13 layer. When the crack propagates, if there are cracks initiated by adjacent 2Cr13 layers near the crack tip, the crack will connect and accelerate the propagation rate.