Case depth in SAE 1020 steel using barkhausen noise

Materials Research

Alessandra Drehmer¹  Gunther J. L. Gerhardt¹  Frank P. Missell¹ 

[1] ,Universidade de Caxias do Sul - UCS Centro de Ciências Exatas e Tecnologia - CCET Caxias do Sul RS ,Brazil

关键词: case depth;    SAE 1020 steel;    Barkhausen noise;    frequency spectrum;   

DOI  :  10.1590/S1516-14392013005000095

来源: SciELO

【 摘 要 】

The most widely used thermochemical process for surface hardening of steels is case hardening. Using several different heat treatments, martensitic surface layers were formed on SAE 1020 steel into which carbon had been diffused. Case depths were measured by traditional destructive techniques. Barkhausen noise measurements were made and both the RMS Barkhausen pulse envelope and the fast Fourier transform (FFT) were obtained from numerical calculation. The FFT amplitudes, functions of frequency, were associated with distance from the sample surface using the skin depth equation δ = 1/ (πfσµ)½ , where f is the frequency of the electromagnetic wave, s is the electrical conductivity, and µ is the magnetic permeability. We define a normalized power index (NPI) which can be used to estimate case depths. The NPI is discussed in relation to the sample microstructure and it is shown that the case depth is most easily determined when the magnetic properties of the surface layer and core are substantially different.

【 授权许可】

CC BY   
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