在反复加载-卸载条件下，测量了35号冷轧钢试件在不同的最大拉应力作用下，试件表面某确定点漏磁场随拉应力的对应关系。试验结果表明，当最大拉应力σmax为255~496 MPa时，磁感应强度-应力(B-σ)近似呈线性关系变化；当σmax为535~611 MPa时，B-σ关系由直线变为折线，并且折线极值点的位置处于100~200 MPa之间；当σmax为637~662 MPa时，B-σ曲线极值点的位置处于382 MPa处，磁感应强度的变化量迅速增大；当σmax为687 MPa时，B-σ关系曲线的极值点移到458 MPa处，磁感应强度的变化量进一步增大。试验得到了试件在拉应力作用下的磁化关系，证实了可以通过磁信号的大小对试件的安全性作出评估。

The relationships of magnetization and stress with different maximum stresses of 35 steel items were measured, during process of extension and shrinkage. It indicated that when the maximum stresses was higher than 255 MPa and lower than 496 MPa, the relationships of magnetization and stress were linear. When the maximum stresses was higher than 535 MPa and lower than 611 MPa, the relationships of magnetization and stress became a broken line and the position of extremum of the line was at about 150 MPa. When the maximum stresses was between 637 MPa and 662 MPa, the position of extremum of the relationships of magnetization and stress was at about 382 MPa and the change of magnetization with the stress was increasing. When the maximum stresses was up to 687 MPa, the position of extremum of the relationships of magnetization and stress moved to 458 MPa approximately and the change of magnetization with the stress was increasing too. It showed that the relationships of magnetization and stress were obtained and that one might be able to estimate the safety for ferromagnetic items by using magnetic signal.