锻压技术

DT4锻造开裂原因分析及控制措施研究

英文标题：Research on the crack mechanism and crack control measures of hot forging solenoid DT4

作者：江学强吉卫曹海桥周朝晖郝爱国

单位：中国工程物理研究院

分类号：TG316

出版年,卷(期):页码：2015,40(6):116-120

摘要：

为了分析电磁纯铁DT4在850～1150 ℃区间锻造时经常出现开裂的原因，选用DT4拉伸试样和压缩试样，在Gleeble 1500上分别进行高温热模拟拉伸试验和压缩试验，同时完成了DT4从α-Fe向γ-Fe相变点检测。试验发现：DT4从α-Fe向γ-Fe的相变温度为900 ℃，在高于相变点温度（912，920和950 ℃）进行拉伸时出现双颈缩，颈缩点温度接近相变温度，在900和950 ℃进行压缩试验，在试样两端出现异常流动。在850～1150 ℃区间内，变形集中在α-Fe向γ-Fe同素异构转变温度区，压缩应力应变曲线显示两相转变区强度比相邻高温区和低温区均低，导致锻造时在相变区出现变形集中而开裂。因此，在锻造过程中避开α-Fe向γ-Fe相变温度区可避免锻造开裂。

For solenoid DT4, the experiments of hot tensile and compress were carried out in the Gleeble 1500 to analyze the reason of cracks at the forging temperature 850-1150 ℃, and the phase transition point from α-Fe to γ-Fe of DT4 was measured. The experiment result shows that the phase transition temperature of DT4 is 900 ℃. When the temperature of hot tensile experiment is higher than the phase temperature such as 912，920，950 ℃, double neck-shrink phenomenon is observed and the temperature of neck-shrink point is almost the same as the phase temperature. When the temperature of compress experiment is 900 and 950 ℃ respectively, abnormal flow phenomenon happens at the ends of specimen. Within 850-1150 ℃, there is deformation concentration on the phase transition zone from α-Fe to γ-Fe and the compress stress-strain curve displays that the strength at the phase transition zone is lower than that of high temperature and low temperature nearby. Therefore the deforming concentration and crack occur easily. Thus, the forging crack can be avoided in the forging process beyond the temperature of phase transition from α-Fe to γ-Fe zone.

基金项目：

中国工程物理研究院发展基金资助项目(2014B0203026)

江学强(1977-)，男，硕士，高级工程师

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