A36船板钢三维原子探针样品的微区定位制备及表征

Micro-location preparation and characterization of three-dimensional atom probe specimen in A36 ship plate steel

为研究A36船板钢中间裂纹形成的微观原因,实验主要利用聚焦离子束(FIB)的精确定位加工功能,在连铸坯的裂纹附近提取特征区域,通过FIB环形切割,制备出感兴趣区域的三维原子探针(3DAP)样品,克服了传统电解抛光制样方法无法定位的缺点,同时通过对样品支架进行修整及角度校正,解决了3DAP针尖样品在分析过程中因存在材料缺陷或尖端曲率半径增大而容易"折断"的问题。然后,利用3DAP研究了制备出的针尖样品的元素分布规律。分析结果显示,在裂纹附近制取的样品中存在C、Mn、Cr和P元素的富集或偏聚,进而验证了这些元素的不均匀分布可能是导致A36船板钢产生裂纹的事实。

In order to study the cause of the middle crack on the cont inuous cast ing slab of A36 ship plate steel,the three-dimensional atom probe （3DAP） specimens extracted from the local characteristic region were fabricated by annular milling with precise position function of the focused ion beam （FIB） , which could solve the problem of location randomness of traditional electrolytic polishing method. Furthermore, the problem of easily broken on specimen during the 3DAP test because of material defect or the oversized tip radius of curvature was successfully resolved by modification and angle correction on the holder. Then, the elements distribution in the prepared tip was analyzed by 3DAP. The results showed that the elements of C,Mn,Cr and P were segregated near the crack,and the non-uniform distribution of these elements may cause the cracks in the A36 ship plate steel.