摘要
TC18钛合金模锻件低倍组织显现出分层现象。通过热模拟试验,利用金相统计并结合微拉伸、SEM等手段,分析对比了近表层表现出的“冷模组织”及近中心层的网篮组织的显微特点及力学性能,探讨了经β锻造及热处理后TC18模锻件由表及里显现出的低倍组织分层机理,提出了低倍分层出现的工艺条件判据并建立了预测模型。结果表明:经单相区加热后,锻件表层变形温度降低(处于双相区)且变形程度小,这使得变形前粗大晶粒的破碎程度降低,难以形成网篮组织,而以“冷模组织”的特征存在,导致了明显的分层现象。特别是“冷模组织”对应的伸长率明显降低,难以达标。随着变形温度(t)的降低,获得网篮组织的临界应变量(εf)增大,根据热模拟试验的系统数据对εf与t之间的关系进行量化表达;以εf为判据,通过二次开发建立了有限元子程序,实现了锻件低倍组织分层的可视化预测。
The macrostructure of TC18 titanium alloy die forging shows delamination.By means of thermal modeling test,optical microscope(OM),micro-tensile tests and scanning electron microscope(SEM),the microstructure characteristics and mechanical properties of“cold die structure”in the near surface and“basketweave structure”in the near center were analyzed and compared.The delamination mechanism of macrostructure from surface to center of TC18 die forging afterβforging and heat treatment was discussed,the process condition criterion of macrostructure delamination was put forward and the prediction model was established.The results show that after heating in the single-phase zone,the surface deformation temperature of the forging decreases(in the two-phase zone)and the deformation degree is small,which makes the crushing degree of coarse grains before deformation low,and it is difficult to form the basketweave structure,so forging surface structure exists with the characteristics of“cold die structure”,resulting in obvious delamination.In particular,the elongation corresponding to“cold die structure”is significantly reduced,which is difficult to meet the standard.With the decrease of deformation temperature(t),the critical strain value(εf)of basketweave structure increases.According to the system data of thermal modeling test,the relationship betweenεf and t was expressed quantitatively;Takingεf as the criterion,the finite element subroutine was established through secondary development,and the visual prediction of macrostructure delamination of forging was realized.
作者
陈雷
张禹森
张启飞
胡峻华
薛明达
郭晓敏
金淼
CHEN Lei;ZHANG Yu-sen;ZHANG Qi-fei;HU Jun-hua;XUE Ming-da;GUO Xiao-min;JIN Miao(College of Mechanical Engineering,Yanshan University,Qinhuangdao 066004,China;China Second Heavy Machinery Group,Deyang Wanhang Die Forging Co.,Ltd.,Deyang 618013,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2023年第2期343-352,共10页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(52075474,51675467)
河北省研究生创新项目(CXZZBS2020049)
河北省自然科学基金资助项目(E2019203560,E2016203284)。
关键词
近Β钛合金
冷模组织
低倍分层
网篮组织
可视化模型
near-βtitanium alloy
cold die structure
macrostructure delamination
basketweave structure
visualisation model
