摘要
A novel laser-electro magnetic acoustic transducer （EMAT） system for nondestructive testing NDT surface crack of continuous casting billet （CCB） is provided. Rayleigh wave generated by line laser source is used to detect the surface crack of CCB. According to the principle of mode conversion from Rayleigh wave to shear wave, the defect signal is received using the shear wave EMAT sensor in a non-contact way. Experiments are carried out on the steel sample with size 30 × 0.2 ×0.2 （mm） of crack. Further, the influences of life off value and distance between EMAT sensor and laser beam on the testing sensitivity are discussed, respectively. It is found that the life off value is the main factor that effects sensitivity of the proposed method. There is a clear prospect of the method applied to test continuously cast bloom at high temperature.
A novel laser-electro magnetic acoustic transducer （EMAT） system for nondestructive testing NDT surface crack of continuous casting billet （CCB） is provided. Rayleigh wave generated by line laser source is used to detect the surface crack of CCB. According to the principle of mode conversion from Rayleigh wave to shear wave, the defect signal is received using the shear wave EMAT sensor in a non-contact way. Experiments are carried out on the steel sample with size 30 × 0.2 ×0.2 （mm） of crack. Further, the influences of life off value and distance between EMAT sensor and laser beam on the testing sensitivity are discussed, respectively. It is found that the life off value is the main factor that effects sensitivity of the proposed method. There is a clear prospect of the method applied to test continuously cast bloom at high temperature.
基金
This work was supported by the National Natural Science Foundation of China （No. 51205240）, Outstanding Young Scientists Program of Shandong （No. BS2011ZZ016）, and Youth Science Funds of Shandong Academy of Sciences （No. 2012-02）.
