本文主要研究内容
作者赵志勇（2019）在《非等温ECAP制备超细晶TC4合金及其脉冲电流处理研究》一文中研究指出：与传统钛合金相比,超细晶钛合金在强度、韧性、塑性、耐磨性等多个方面具有明显优势。等通道转角挤压(ECAP)技术是制备超细晶金属材料的最有效方法之一,虽然已有研究表明能够将ECAP应用于超细晶TC4合金的制备,但是,制备的技术难度和成本非常高。因此,本文通过优化ECAP模具设计和改善工况条件,利用非等温ECAP在较低温度条件下制备了超细晶TC4合金,并对其室温力学性能和热变形行为进行了深入讨论与分析;结合脉冲电流处理技术,进一步改善了ECAP剧烈塑性变形TC4合金的显微组织及其力学性能。压缩和剪切是ECAP变形过程中的两种主要变形形式。本文首先通过基于脉冲电流在线加热TC4合金的压缩和剪切变形研究,分析了脉冲电流的热效应和非热效应对TC4合金力学性能和显微组织的影响,研究了TC4合金的非等温变形行为。一方面,脉冲电流的焦耳热效应是导致TC4合金变形抗力降低的主要原因,在通电状态下,TC4合金试样的温度与电流密度、试样形状尺寸、接触压强、接触面积等因素密切相关。另一方面,脉冲电流的非热效应促进了TC4合金压缩变形过程中的动态再结晶和α→β相变;在TC4合金快速剪切变形过程中,脉冲电流促进了晶粒的晶内变形,避免应力集中导致沿晶界扩展的微裂纹产生,因此,脉冲电流的非热效应对提高TC4合金的塑性变形能力有重要作用。通过不同变形速度条件下的TC4合金压缩和剪切力学曲线对比分析,表明高的变形速率有利于温度逐渐降低的TC4合金非等温塑性变形,为TC4合金非等温ECAP变形工艺提供了重要的参考依据。通过降低试样与挤压凹模以及挤压凹模与支撑模具之间的热传导,并改善其润滑条件,缩短工序时间,以及提高挤压速度,利用非等温ECAP工艺实现了TC4合金的剧烈塑性变形,可以进行最多四道次的ECAP变形,累积应变达到4.5,成功制备了超细晶TC4合金。显微组织观察表明,四道次ECAP制备超细晶TC4合金中包含有大量的亚微米晶粒和胞状亚结构,同时,在显微组织中观察到大量形变孪晶,说明孪生在TC4合金非等温ECAP过程中起到重要协调变形作用。室温力学性能测试结果表明,ECAP制备超细晶TC4合金的显微硬度和抗压强度都有显著提升,分别达到392HV和1435MPa,与原始TC4合金相比,分别提高了6.5%和12%。对比未经ECAP变形TC4合金(Pre-ECAP)和ECAP制备超细晶TC4合金(Post-ECAP)的热压缩变形行为。当变形温度为500℃变形时,Post-ECAP合金的压缩强度较高;当变形温度为600℃和700℃时,Post-ECAP合金的压缩强度低于Pre-ECAP合金,表现出较好的塑性变形能力。以Pre-ECAP和Post-ECAP为原材料,采用热镦挤工艺,在650℃~700℃成形了TC4合金紧固件螺钉,通过宏观形貌观察,Pre-ECAP成形紧固件螺钉端部出现裂纹,表明Post-ECAP的热成形性能优于Pre-ECAP;经室温拉伸力学性能测试,Post-ECAP紧固件螺钉的抗拉强度达到1190Mpa,较Pre-ECAP提高了15.5%,从而验证了超细晶TC4合金在热成形性能和力学性能方面的优越性。尽管ECAP制备的超细晶TC4合金具有非常高的室温强度,但是因其较高的位错密度,组织均匀性和稳定性差,导致其室温塑性很差。传统工艺中通常采用退火热处理的方式提高其塑性和韧性,然而退火处理时间过长或者温度过高都会导致晶粒的长大,降低材料的力学性能。为获得更优的力学性能,本文采用脉冲电流处理经ECAP剧烈塑性变形的TC4合金。结果表明,脉冲电流能够在较短时间内促进剧烈塑性变形TC4合金的静态再结晶和α→β相变,降低其位错密度,获得了具有稳定均匀显微组织的超细晶TC4合金。通过室温拉伸试验表明,在强度没有明显降低的前提下,ECAP制备超细晶TC4合金的延伸率提高了66.5%。与传统退火处理工艺相比,脉冲电流处理为剧烈塑性变形TC4合金显微组织的改善和综合力学性能的提升提供了一种节能、高效、环保的新技术。
Abstract
yu chuan tong tai ge jin xiang bi ,chao xi jing tai ge jin zai jiang du 、ren xing 、su xing 、nai mo xing deng duo ge fang mian ju you ming xian you shi 。deng tong dao zhuai jiao ji ya (ECAP)ji shu shi zhi bei chao xi jing jin shu cai liao de zui you xiao fang fa zhi yi ,sui ran yi you yan jiu biao ming neng gou jiang ECAPying yong yu chao xi jing TC4ge jin de zhi bei ,dan shi ,zhi bei de ji shu nan du he cheng ben fei chang gao 。yin ci ,ben wen tong guo you hua ECAPmo ju she ji he gai shan gong kuang tiao jian ,li yong fei deng wen ECAPzai jiao di wen du tiao jian xia zhi bei le chao xi jing TC4ge jin ,bing dui ji shi wen li xue xing neng he re bian xing hang wei jin hang le shen ru tao lun yu fen xi ;jie ge mai chong dian liu chu li ji shu ,jin yi bu gai shan le ECAPju lie su xing bian xing TC4ge jin de xian wei zu zhi ji ji li xue xing neng 。ya su he jian qie shi ECAPbian xing guo cheng zhong de liang chong zhu yao bian xing xing shi 。ben wen shou xian tong guo ji yu mai chong dian liu zai xian jia re TC4ge jin de ya su he jian qie bian xing yan jiu ,fen xi le mai chong dian liu de re xiao ying he fei re xiao ying dui TC4ge jin li xue xing neng he xian wei zu zhi de ying xiang ,yan jiu le TC4ge jin de fei deng wen bian xing hang wei 。yi fang mian ,mai chong dian liu de jiao er re xiao ying shi dao zhi TC4ge jin bian xing kang li jiang di de zhu yao yuan yin ,zai tong dian zhuang tai xia ,TC4ge jin shi yang de wen du yu dian liu mi du 、shi yang xing zhuang che cun 、jie chu ya jiang 、jie chu mian ji deng yin su mi qie xiang guan 。ling yi fang mian ,mai chong dian liu de fei re xiao ying cu jin le TC4ge jin ya su bian xing guo cheng zhong de dong tai zai jie jing he α→βxiang bian ;zai TC4ge jin kuai su jian qie bian xing guo cheng zhong ,mai chong dian liu cu jin le jing li de jing nei bian xing ,bi mian ying li ji zhong dao zhi yan jing jie kuo zhan de wei lie wen chan sheng ,yin ci ,mai chong dian liu de fei re xiao ying dui di gao TC4ge jin de su xing bian xing neng li you chong yao zuo yong 。tong guo bu tong bian xing su du tiao jian xia de TC4ge jin ya su he jian qie li xue qu xian dui bi fen xi ,biao ming gao de bian xing su lv you li yu wen du zhu jian jiang di de TC4ge jin fei deng wen su xing bian xing ,wei TC4ge jin fei deng wen ECAPbian xing gong yi di gong le chong yao de can kao yi ju 。tong guo jiang di shi yang yu ji ya ao mo yi ji ji ya ao mo yu zhi cheng mo ju zhi jian de re chuan dao ,bing gai shan ji run hua tiao jian ,su duan gong xu shi jian ,yi ji di gao ji ya su du ,li yong fei deng wen ECAPgong yi shi xian le TC4ge jin de ju lie su xing bian xing ,ke yi jin hang zui duo si dao ci de ECAPbian xing ,lei ji ying bian da dao 4.5,cheng gong zhi bei le chao xi jing TC4ge jin 。xian wei zu zhi guan cha biao ming ,si dao ci ECAPzhi bei chao xi jing TC4ge jin zhong bao han you da liang de ya wei mi jing li he bao zhuang ya jie gou ,tong shi ,zai xian wei zu zhi zhong guan cha dao da liang xing bian luan jing ,shui ming luan sheng zai TC4ge jin fei deng wen ECAPguo cheng zhong qi dao chong yao xie diao bian xing zuo yong 。shi wen li xue xing neng ce shi jie guo biao ming ,ECAPzhi bei chao xi jing TC4ge jin de xian wei ying du he kang ya jiang du dou you xian zhe di sheng ,fen bie da dao 392HVhe 1435MPa,yu yuan shi TC4ge jin xiang bi ,fen bie di gao le 6.5%he 12%。dui bi wei jing ECAPbian xing TC4ge jin (Pre-ECAP)he ECAPzhi bei chao xi jing TC4ge jin (Post-ECAP)de re ya su bian xing hang wei 。dang bian xing wen du wei 500℃bian xing shi ,Post-ECAPge jin de ya su jiang du jiao gao ;dang bian xing wen du wei 600℃he 700℃shi ,Post-ECAPge jin de ya su jiang du di yu Pre-ECAPge jin ,biao xian chu jiao hao de su xing bian xing neng li 。yi Pre-ECAPhe Post-ECAPwei yuan cai liao ,cai yong re dui ji gong yi ,zai 650℃~700℃cheng xing le TC4ge jin jin gu jian luo ding ,tong guo hong guan xing mao guan cha ,Pre-ECAPcheng xing jin gu jian luo ding duan bu chu xian lie wen ,biao ming Post-ECAPde re cheng xing xing neng you yu Pre-ECAP;jing shi wen la shen li xue xing neng ce shi ,Post-ECAPjin gu jian luo ding de kang la jiang du da dao 1190Mpa,jiao Pre-ECAPdi gao le 15.5%,cong er yan zheng le chao xi jing TC4ge jin zai re cheng xing xing neng he li xue xing neng fang mian de you yue xing 。jin guan ECAPzhi bei de chao xi jing TC4ge jin ju you fei chang gao de shi wen jiang du ,dan shi yin ji jiao gao de wei cuo mi du ,zu zhi jun yun xing he wen ding xing cha ,dao zhi ji shi wen su xing hen cha 。chuan tong gong yi zhong tong chang cai yong tui huo re chu li de fang shi di gao ji su xing he ren xing ,ran er tui huo chu li shi jian guo chang huo zhe wen du guo gao dou hui dao zhi jing li de chang da ,jiang di cai liao de li xue xing neng 。wei huo de geng you de li xue xing neng ,ben wen cai yong mai chong dian liu chu li jing ECAPju lie su xing bian xing de TC4ge jin 。jie guo biao ming ,mai chong dian liu neng gou zai jiao duan shi jian nei cu jin ju lie su xing bian xing TC4ge jin de jing tai zai jie jing he α→βxiang bian ,jiang di ji wei cuo mi du ,huo de le ju you wen ding jun yun xian wei zu zhi de chao xi jing TC4ge jin 。tong guo shi wen la shen shi yan biao ming ,zai jiang du mei you ming xian jiang di de qian di xia ,ECAPzhi bei chao xi jing TC4ge jin de yan shen lv di gao le 66.5%。yu chuan tong tui huo chu li gong yi xiang bi ,mai chong dian liu chu li wei ju lie su xing bian xing TC4ge jin xian wei zu zhi de gai shan he zeng ge li xue xing neng de di sheng di gong le yi chong jie neng 、gao xiao 、huan bao de xin ji shu 。
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论文作者分别是来自哈尔滨工业大学的赵志勇，发表于刊物哈尔滨工业大学2019-12-07论文，是一篇关于超细晶合金论文,等通道转角挤压论文,脉冲电流处理论文,剪切变形论文,热变形行为论文,哈尔滨工业大学2019-12-07论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自哈尔滨工业大学2019-12-07论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
标签：超细晶合金论文; 等通道转角挤压论文; 脉冲电流处理论文; 剪切变形论文; 热变形行为论文; 哈尔滨工业大学2019-12-07论文;