特厚钢板中一种特殊缺陷的超声波检测方法

Ultrasonic Detection Method for A Special Defect of Ultra Heavy Plate

厚度为200 mm的特厚钢板,按合同要求进行超声波探伤,执行EN10160—1999 S1 E1标准。超声波探伤时钢板缺陷当量没有超标,但缺陷处底波下降严重。通过采用不同的探伤灵敏度和检测方法,观察缺陷处的波型,确定该缺陷为大型的危害性缺陷。经解剖及对缺陷处取样做金相分析,并追溯该钢板所用连铸坯低倍检测结果,确定了该钢板缺陷为大型内裂。通过该探伤案例表明:采用纵波五次底波法检测,通过观察缺陷波型和底波状况,可以用超声波探伤检测出特厚钢板中大型内裂缺陷。

Ultrasonic wave inspection is required under the contract comply with the requirements of EN10160 - 1999 S1/E1 for the heavy plates with thickness 200mm. When detected by Ultrasonic flaw, the defect equivalent of plate do not exceed the require- ments of standard, but the defects at the bottom wave drop seriously. Adopt different detection sensitivity and inspection method to ob- serve the wave type at the point of defect and make sure that it is large harmful defects. After cutting and metal]ographic analysis of the sample, and trace to the result of macroscopic examination for slab, large internal crack are identified in the plates. The testing cases show that： large internal crack defect in ultra heavy plates can be ultrasonic detected through five bottom longitudinal wave method in the defects detection by observing the wave pattern and bottom wave condition.