热处理工艺对Ti-555装甲钛合金微观组织与力学性能的影响

Effect of heat treatment process on microstructure and mechanical properties of Ti-555 armored titanium alloy

利用光学显微镜、扫描电镜和万能拉伸机等研究了退火温度、固溶温度、时效时间等工艺参数对新型装甲防护用Ti-555钛合金力学性能、微观组织和晶体结构的影响。结果表明:采用900℃×2 h空冷+550℃×6 h时效的工艺对Ti-555钛合金板材进行热处理后,其具有最优的强塑性和强韧性匹配;加热保温后的冷却速度对合金的强塑性匹配有显著影响,较快的冷却速度使得转变的β组织中形成细针状次生α相和次生α′相,经过进一步时效处理后,合金具有较高的强塑性匹配;随着保温时间的增加和冷却速度的降低,晶体结构由基面织构向柱面织构转变,并出现棱锥面织构,使合金断面收缩率降低,不利于其成形。

Effect of process parameters such as annealing temperature,solution temperature,and aging time on mechanical properties,microstructure,and crystal structure of a new type of Ti-555 titanium alloy for armored protection was studied using optical microscope,scanning electron microscopy and universal tensile machine.The results show that the Ti-555 titanium alloy sheet has the optimal matching of strength plasticity and strength toughness after heat treatment using the process of 900℃×2 h air cooling+550℃×6 h aging.The cooling rate after heating and holding has a significant effect on the strength plasticity matching of the alloy.A faster cooling rate leads to the formation of fine needle-like secondaryαphases and secondaryα′phases in the transformedβmicrostructure.After further aging treatment,the alloy has a higher strength plasticity matching.With the increase of holding time and the decrease of cooling rate,the crystal structure changes from basal texture to cylindrical texture,and a pyramidal texture appears,which reduces the reduction of area of the alloy and is not conducive to its forming.