摘要
研究了双态组织的Ti-6Al-4V-0.55Fe(TC4-0.55Fe)钛合金在不同热处理制度(固溶时效、双重退火)下和引入预拉伸后的微观组织及力学性能,并分析了合金显微组织与力学性能之间的联系。发现合金固溶时效和双重退火热处理下随着时效和低温退火温度升高合金中微米级的片层α相厚度逐渐增大,强度降低、塑性提高。固溶时效热处理下随着时效温度的升高合金屈服强度从530℃的873 MPa左右下降到590℃的862 MPa左右,而延伸率提高3.2%。双重退火热处理试样的屈服强度随着低温退火温度的升高逐步降低,延伸率相比于固溶时效有了很大提高,最好可达到23.6%。由于固溶时效和双重退火对合金强度提升不明显,时效温度和低温退火温度均为590℃时,屈服强度差别不大,双重退火试样塑性更优于固溶时效,所以针对该温度的双重退火工艺引入预拉伸强化,对合金在固溶处理和低温退火处理中间进行预拉伸。引入预拉伸后,晶粒α相发生了明显的变形,形成无沉淀区(PFZ),进一步退火后无沉淀区(PFZ)中析出大量细小的二次α相(α_(s)),引入预拉伸后进行退火可以在提升钛合金屈服强度的同时只降低极少的塑性,其中预拉伸变形1%的试样α_(s)含量最高,强度较引入预拉伸前提高68 MPa,延伸率仅下降4%,力学性能最优。通过本研究可知,TC4-0.55Fe钛合金在经过固溶处理后继续进行预拉伸和时效处理,可以有效提升合金的综合力学性能。
This paper investigated the effects of different heat treatment processes(solution aging and double annealing)and pre-stretching on the microstructure and mechanical properties of Ti-6Al-4V-0.55Fe(TC4-0.55Fe)alloy with duplex microstructure,and the relationship between its microstructure and mechanical properties were discussed.The TC4-0.55Fe alloy microstructures and mechanical properties after solution aging and double annealing were compared,it is found that the thickness of the lamellarαphase gradually increases with the increase in aging and low temperature annealing temperature,which leads the strength of the alloy decreases and the plasticity increases.Under the solution aging treatment,the yield strength of the alloy decreases from 873 MPa at 530℃ to 862 MPa at 590℃ and the elongation increases by 3.2%.The yield strength of the double annealing heat treated sample decreases gradually with the increase in the low temperature annealing temperature,but the elongation has been greatly improved compared with the solution aged,and the best is 23.6%.Because the strength of TC4-0.55Fe alloy is not significantly improved by solution aging and double annealing,the plasticity of the double annealing sample is better than that of the solution aging when the aging and low temperature annealing temperature is 590℃,so the double annealing process at 590°C is selected to combine the pre-stretching strengthening,the pre-stretching is introduced between the solution and low temperature annealing.After the introduction of pre-stretching,theαphase deformation is obvious,and the precipitation-free zone(PFZ)forms.A large amount of fine secondaryαphases(α_(s))are precipitated in the PFZ after annealing.The annealing after the pre-stretching can improve the yield strength of TC4-0.55Fe alloy and only reduce plasticity little.Among them,the sample with 1% pre-stretching deformation has the highest content of α_(s) phase,the field strength is increased by 68 MPa compared with that of the double annealing,and the elongation is only decreased by 4%,the comprehensive mechanical properties are the best.According to this study,it can be concluded that the comprehensive mechanical properties of TC4-0.55Fe titanium alloy can be improved by pre-stretching and aging strengthening after solution.
作者
刘思侬
张晶棋
刘博玮
李鑫
李峰
常辉
Liu Sinong;Zhang Jingqi;Liu Bowei;Li Xin;Li Feng;Chang Hui(College of Materials Science and Engineering,Nanjing Tech University,Nanjing 211816,China;Tech Institute for Advanced Materials,Nanjing Tech University,Nanjing 211816,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2023年第10期3485-3494,共10页
Rare Metal Materials and Engineering
基金
国家重点研发计划(2021YFB3700801)
国家级大学生创新创业训练计划(202110291008Z)
江苏高校优势学科建设工程资助项目。
