基于组织统计分析的大型铸件无损评估方法

Non-destructive Evaluation Method of Large-scale Casting Piece Based on Metallographic Structure Statistical Analysis

针对大型、薄壁、复杂、整体、精密钛合金铸件各区域组织分布差异较大的问题,提出一种基于组织统计分析的大型铸件无损评估方法,在不破坏铸件的前提下,通过手持式显微镜获得铸件表层组织信息,建立表层组织统计学模型,给出铸件组织整体分布结果。通过对比分析无损评估获得的组织分布结果(A方法)与解剖取样后表层金相检测结果(B方法),研究该无损评估方法的可行性。结果表明:大型ZTC4钛合金铸件的晶粒尺寸均值、晶粒尺寸分布曲线的半高宽均符合高斯分布特征;采用无损评估方法能够有效评估其组织分布状况;本实验条件下,两种方法获得的铸件晶粒尺寸均值均随壁厚增加而线性增大,其变化率偏差在6%的范围内;所得晶粒尺寸分布曲线半高宽的相对偏差随铸件壁厚的增加呈指数增加的趋势,趋近于26%。

Aimed at the great metallographic structure differences between every part of the large-scale thin-wall complex integral precise titanium alloy casting, a non-destructive evaluation method based on metallographic structure statistical analysis is proposed Under the non-destructive condition, the casting skin structure information is given by means of handheld microscope. The casting skin structure statistic model is established. And the result of integral casting structure is given. Through comparative analysis between non-destructive evaluation （Method A） and metallography detection of the dissect sample （Method B）, the results show that the non-destructive evaluation evaluates the metallographic structure effectively. The mean value and half-width of the grain size distribution curves fit the characteristic of Gaussian distribution. And the grain size mean value in both two methods increase linearly along with the casting thickness, and the slope deviation is within the limits of 6%; the half-width relative deviation increases exponentially along with the casting thickness, approached 26%