基于数字图像处理的粉末冶金高速钢中碳化物表征研究

Characterization of carbides in powder high-speed steel based on digital image processing

针对粉末冶金高速钢中碳化物小、多、杂带来的表征难题,基于数字图像处理技术,借助高通量场发射扫描电镜,建立了一种粉末冶金高速钢中的碳化物定量统计表征方法。该方法通过对大量SEM图像进行滤波、双阈值分割、特征提取、膨胀、腐蚀及骨架提取等处理,快速获取SEM图像中碳化物定量统计分布信息。并将该方法应用于不同状态AHPT15M粉末冶金高速钢中MC、M_(6)C型碳化物尺寸、数量及分布的定量统计分析,结果显示:AHPT15M高速钢中碳化物尺寸范围分布为0~5μm,其中2μm以下碳化物占碳化物总数的95%以上。退火态高速钢中碳化物面积为21.62%,其中MC型碳化物为14.05%,M_(6)C型碳化物为7.57%;试样经热处理工艺后,碳化物面积减少为15.05%,其中MC型碳化物面积为10.47%,M_(6)C型碳化物为4.58%;所得碳化物定量统计结果与物理化学相分析统计结果相符。结果表明,该方法可快速统计识别大量粉末冶金高速钢SEM图像中的碳化物,统计结果更全面。

Aiming at the problems of characterization of small,numerous and complicated carbides in powder metallurgy high speed steel,based on the high-throughput field emission scanning electron microscope,a quantitative characterization method of carbides in powder metallurgy high speed steel was established by means of digital image processing.By filtering,double threshold segmentation,feature extraction,expansion,corrosion and skeleton extraction on a large number of SEM images,the method can quickly obtain the quantitative statistical distribution information of carbides in SEM images.It has been applied to the quantitative analysis of the size,quantity and distribution of MC,M_(6)C type carbides of AHPT15M in different states.The results show that the carbide size distribution of AHPT15M is 0-5μm,and the carbide size below 2μm accounts for more than 95%of the total carbide.The area fraction of carbide area in annealed speed steel is 21.62%,of which the proportion of MC type carbide is 14.05%,and that of M_(6)C type carbide is 7.57%.After heat treatment,the area fraction of carbide decreases to 15.05%,of which the MC carbide is 10.47%,and that the M_(6)C carbide is 4.58%.The quantitative result of carbides obtained by this method is consistent with the statistical data of physicochemical phase analysis.It shows that this method can quickly identify carbides of a large number of images in powder metallurgy high speed steel,and the results aremorecomprehensive.