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针对合金钢对接焊缝中倾斜裂纹定量困难的问题,提出了TOFD(超声衍射时差法)定量检测倾斜裂纹的方法。基于焊缝纵断面方向上两次B扫查间隔、两次B扫查过程中声程最短时编码器移动距离差和倾斜裂纹三者所构成的三角形,利用三者之间几何关系实现裂纹倾斜角度与长度定量。模拟结果表明:对长度5,10,60mm,倾斜角度范围为10°~90°的裂纹进行定量验证,角度定量误差小于1°;长度定量相对误差小于5%。试验针对对接焊缝试块中长度60mm,倾斜角度范围为30°~60°的倾斜裂纹应用此方法进行定量验证,可得裂纹角度定量误差最大值为0.29°;长度定量误差最大值为0.94mm。
In order to solve the problem of the quantitatively slanting crack in the butt weld of alloy steel, a method of TOFD (Ultrasonic Diffraction Time Difference Method) is proposed to quantitatively detect the slant crack. Based on the three B-scan intervals in the longitudinal direction of the weld, the triangle formed by the difference of the moving distance of the encoder and the inclined crack in the shortest acoustic path during the two B-scan processes, the crack inclination is achieved by the geometric relationship among the three Angle and length of quantitative. The simulation results show that the quantitative verification of the cracks with the length of 5, 10, 60mm and the inclined angle range of 10 ° ~ 90 ° is less than 1 °, and the relative error of the length measurement is less than 5%. The test for the butt weld test block with a length of 60mm, the tilt angle range of 30 ° ~ 60 ° of the tilt crack quantitative verification using this method, the crack can be obtained quantitative maximum error angle of 0.29 °; maximum length of the quantitative error of 0.94mm .