Residual stress in low temperature carburised layer of austenitic stainless steel

Abstract

Microstructure, elements concentration and residual stress of a low temperature carburised layer on 316L austenitic stainless steel were investigated by optical microscopy, electron probe microanalysis, nanoindentation and X-ray diffraction (XRD). The results show that surface carbon concentration and nanohardness increase significantly after low temperature carburisation in the mixture gas of 30 vol.-% CO–30 vol.-% H₂–40 vol.-%N₂ at 743 K for 20 h, while Young’s modulus keeps unchanged. A finite element model was proposed to simulate the nanoindentation of unstressed carburised layer based on the results of nanoindentation experiments. Combined with the experimental and simulation results, the residual stress was calculated based on Suresh model, which agrees well with the corrected data by XRD method. The surface displacement around indenter was discussed.

Keywords:

• Low temperature carburisation
• Austenitic stainless steel
• Residual stress
• Nanoindentation
• Finite element simulation

Acknowledgements

The authors gratefully acknowledge the support provided by the National Natural Science Foundation of China (51475224), the Key University Science Research Project of Jiangsu Province (14KJA470002) and the Postgraduate Cultivation and Innovation Project (CXZZ12_0420).