Correlation Dependences between Mechanical Properties and Magnetic Parameter of the 41сr4 Steel

It is shown that the mechanical properties (relative yield strength σ0,2, tensile strength σв, relative constriction ψ) and hardness HRC of the 41Cr4 (DIN) steel change monotonically when the tempering temperature Tо changes after quenching and closely correlate with each other. The linear regression equations are presented describing interrelations σ0,2, σв and ψ on HRС of the 41Cr4 steel, calculation errors for them and correlation coefficients. It is shown that the coercive force Hc of the 41Сr4 steel does not have an unambiguous dependence with its hardness HRC over the entire range of variation of Tо, and the relaxation magnetization of the 41Cr4 steel cannot be used for non-destructive testing of its hardness due to low measurement accuracy. For the magnetic structuroscopy of the 41Сr4 steel, parameter Hc1 is proposed, for the calculation of which its Hc and relation of the residual magnetization to the saturation magnetization is used. It is shown that the calculation results of Hc1 do not have a high relative error, clearly depend on Tо of the 41Сr4 steel in the practically important range of its change and are highly sensitive to changes in the hardness HRC of the 41Сr4 steel. The equation for the correlation dependence of HRC on the parameter Hc1 is given. This equation and the equations of dependence of σ0,2, σв and ψ on HRС are used to build correlation dependences of σ0,2, σв and ψ on the parameter Hc1. It is shown that the constructed dependencies can be used for non-destructive magnetic testing of the mechanical properties of the 41Сr4 steel in a practically important range of their variation