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.-% H 2 -40 vol.-%N 2 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.

Effect of Residual Stress in Surface Layer on Plastic Yield Inception

“…In the above-mentioned simulations, the elastic moduli of the surface layer and substrate are the same. Sometimes, the elastic modulus is less sensitive to surface treatment, but residual stress originates after surface treatment [32,33]. However, in most practical cases, the material parameters of the surface layer and substrate are not identical.…”

Numerical Analysis of Stress Gradient and Traps Effects on Carbon Diffusion in AISI 316L during Low Temperature Gas Phase Carburization

“…The experimental results demonstrated that applied compressive stress can retard the fast diffusion process comparing to an unstressed state. It is well known that low temperature surface carburization of austenitic stainless steel can result in tremendous compressive stresses (GPa level) with graded distribution as a consequence of the lattice expansion associated with the dissolution of interstitial carbon [5,[13][14][15]. It has been well established that the diffusion of atoms is dependent on the chemical potential gradient, and the stress gradient is one of the important factors determining the chemical potential gradient [16].…”

Experimental and numerical analysis of residual stress in carbon-stabilized expanded austenite

“…9. Rong et al [17] determined residual stresses in the low-temperature carburized case based on a nano-indentation technique proposed by Suresh et al [18]. This method is more complicated compared to XRD method, but it does not lead to ghost stresses.…”

“…For comparison the composition profile obtained by electron probe microanalysis (EPMA) [22] and the residual stress-depth profile obtained by Rong et al [17] with nano-indentation for a sample carburized under identical conditions, are given in Fig. 1 [24].…”