Magnetic Barkhausen Noise Evaluation Of Method For Mechanical Properties Of Alloy Steel Made By Laser Addiction

Hardness / strength mechanical properties are the key reference indicators for wear and fatigue properties of alloy steel materials.Quantitative non-destructive testing of hardness / strength is critical for engineering applications of additive manufacturing alloy steel parts.In view of the shortcomings of the evaluation method of hardness / strength of the laser additive manufacturing forming parts,this paper explores the quantitative non-destructive evaluation method of hardness / strength for the alloy steel material using the Barkhausen noise method.Starting from the basic principles of ferromagnetic materials,the basic principles and methods of ferromagnetic materials hardness / strength testing are summarized.Based on the test results,the Barkhausen noise method is used to evaluate and study the hardness /strength mechanical properties of the alloy steel manufactured by additive manufacturing.In this paper,starting from the magnetic properties of ferromagnetic materials,based on the dynamic equations satisfied by the magnetic domain movement,the hysteresis effect is analyzed from the perspective of magnetization,and the relationship between the Barkhausen noise signal and the hysteresis model is derived.A mathematical model of magnetic flux change and irreversible magnetic domain wall motion during magnetization is presented.Secondly,it introduces the detection principle,system design and evaluation parameters of the Barkhausen signal.Then,taking the isotropic 24 CrNiMo alloy steel as the research object,the relationship between the microstructure of different heat-treated alloy steel-Buckhausen signal-mechanical properties was analyzed and a calibration model for evaluating the 24 CrNiMo alloy steel specimen was established.The research results show that with the continuous decrease of hardness / strength,the root mean square of the Buckhausen signal,the reconstruction hysteresis loss,the reconstruction residual magnetism,and the pulse energy all show a monotonous increasing trend.The prediction sensitivity is high and the prediction accuracy and All meet the requirements of 10% for engineering applications.Based on this evaluation method,a quantitative evaluation study on the hardness / strength of the shaped parts manufactured by laser additive manufacturing was carried out.Compared with the prediction results of the hardness / strength of isotropic alloy steel,the prediction error of unidirectional mechanical property calibration model is generally too large.Finally,a weighted regression model is established to quantitatively characterize the mechanical properties of alloy steel manufactured by additive manufacturing.In the regression model,the characteristic parameters of Barkhausen and the hardness /strength of the material are all linearly related.The minimum correlation is 0.95 and the maximum is as high as 0.99,and the correlation is further improved.Its prediction accuracy is improved by about 2% compared with the one-way calibration model.The pulse energy model’s prediction accuracy of hardness / strength reaches 5.88% and4.68%,which improves the model’s prediction redundancy.