摘要
利用OM,SEM,能谱分析和显微硬度等测试方法对Ti-24Al-15Nb-1.5Mo/TC11双合金焊接接头的显微组织特征及硬度进行了分析.结果表明,焊接热输入为135kJ/m时,焊缝熔合区柱状晶由均匀密集的α′相针状马氏体和少量α相组成,显微硬度平均值为447HV.焊接热输入增大到150kJ/m时,熔合区α′相明显减少,焊缝TC11合金侧热影响区的短针状α+β组织变为粗大的长针状组织,Ti-24Al-15Nb-1.5Mo热影响区的β晶粒变得更粗,显微硬度平均值降为402HV.这主要是因为增大热输入使焊缝合金元素含量的比例发生变化,并且冷却速度下降使焊缝组织形态和分布改变,最终导致显微硬度降低.合金元素Ti,Al,Nb的含量在焊缝边界发生突变,但在焊缝熔合区达到一个新的平衡.
Microstructure evolution characterization of the Ti-24Al-15Nb-1.5Mo/TC11 dual alloys welded joints obtained on the condition of different electron beam heat input was studied by optical microscope,scanning electron microscope,energy spectrum and micro-hardness analysis. The results show that the energy input have an important effect on the microstructure,grain size,micro-hardness and alloy elements content of welded joints. The microstructure is made up of homogeneous acicular martensite α'phase in fusion zone(FZ) and the average micro-hardness value is 447HV when heat input E=135 kJ/m is utilized. With heat input increasing to 150 kJ/m,the number of α'phase decreases in FZ,short acicular α+β phase become coarser in heat-affected zone(HAZ) of TC11,coarse β grains become larger in HAZ of Ti-24Al-15Nb-1.5Mo and the average micro-hardness value drops to 402HV. The result is attributed to the changed content of alloy elements and lower cooling velocity caused by increasing heat input. The content of element Ti,Al and Nb is changed abruptly in the boundary of the joint,but these elements evenly distribute in each zone and hardly diffuse.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2009年第7期33-36,40,共5页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(50775187)
关键词
电子束焊接
双合金
热输入
微观组织
显微硬度
electron beam welding
dual alloy
heat input
fine texture
microstructure
