Statistical estimation of Barkhausen noise testing results at various quenched and tempered steel

The paper treats the application of the micromagnetic method to the determination of hardness of C45 hardened-and-tempered steel on the basis of a voltage signal of the magnetic Barkhausen noise. In addition to the assessment of reproducibility of results the discriminatory power of the variance in determining the hardness achieved was determined by means of the statistical t-test. The statistical treatment of the Barkhausen-noise voltage-signal variance was used to assess two neighbouring specimens showing a difference in the tempering temperature, i.e. ΔT1=10°C, ΔT2=20°C and ΔT3=40°C respectively. The statistical analysis of the discriminating power of the variances considered two neighbouring tempering temperatures in the same temperature range, i.e. between TT1=220°C to TT29=500°C.