Numerical analysis of distortion due to inhomogeneous distribution of martensite start temperature within SAE 52100 bearing rings

This paper reports about numerical investigations regarding the spatial distribution of martensite start temperature (M-s) within bearing rings made out of SAE 52100 (100Cr6). Out-of-roundness values due to inhomogeneous M. distribution are calculated by means of FIE simulations. In a first step the distribution of M-s is modelled with simple trigonometric functions with different wavelengths and amplitudes of M-s. In addition, more complex distributions of M-s are investigated by means of superposition of different trigonometric functions. Simulations with the commercial FE simulation program SYSWELD (R) yield dependencies of out-of-roundness values of bearing rings on wavelength and amplitude of M-s. The numerical study is supplemented by experimental investigations concerning the distribution of M-s. Typical scatter-bands of M-s within a work piece were found to be +/- 10 K. Concerning this scatter-band, different possible distributions of M-s are analysed by Fourier transformation. With the resulting trigonometric functions the out-of-roundness values are calculated and compared with experimental data.