本文主要研究内容
作者臧千昊（2019）在《高Zn含量Al-Zn-Mg-Cu合金变形行为、组织演变及力学性能的研究》一文中研究指出：近些年,能源匮乏、全球气候变暖等能源与环境问题日益严峻,旨在节能减排的汽车轻量化显得愈发重要。目前,铝合金在汽车轻量化材料中仍占据重要地位。高强度Al-Zn-Mg-Cu合金也被应用于汽车轻量化材料上,汽车结构件以高性能铝代钢是实现汽车轻量化的一种有效途径。同时汽车轻量化材料的制备也需满足绿色制造、快速制造、优质制造的目标。双辊铸轧技术(Twin roll casting,TRC)可有效缩短铝合金板材制备流程,减少能耗和降低成本。然而Al-Zn-Mg-Cu合金的合金元素含量高、强度大,用TRC技术制备仍存在一定的困难。本论文根据TRC工艺的特点,同时为了提高合金强度,设计了高Zn含量的Al-7.9Zn-2.7Mg-2.0Cu(wt.%)合金,制定了TRC+退火处理+轧制的工艺流程。通过对比研究TRC合金和金属型铸造(Permanent mold casting,PMC)合金的组织以及TRC和PMC合金轧制变形后合金薄带的组织和力学性能,探究了 TRC工艺制备高Zn含量Al-Zn-Mg-Cu合金的可行性。基于快速制造的理念,利用退火处理调控合金凝固过程中形成的第二相粒子,研究了后续轧制过程中第二相粒子对合金再结晶行为的影响机理。从而达到控制轧制薄带组织和织构,降低合金薄带塑性各向异性的目的。本文采用双辊铸轧技术成功制备了宽度为130mm,厚度为5.5mm的A1-7.9Zn-2.7Mg-2.0Cu合金条带,确定了起始浇注温度为690 ℃、铸轧速度为2.36～2.54 m/min和轧辊间间隙为4.0mm的铸轧工艺参数。TRC条带组织呈现出均匀的等轴树枝晶且二次枝晶间距细小,在枝晶间形成了细小的Mg(Zn,Al,Cu)2相。短时间的退火处理(480 ℃/1h)即可有效地消除TRC组织中的第二相。然而,PMC合金铸锭中第二相尺寸较大。经过400℃/1h退火处理,大部分的第二相仍保留在组织中,PMC合金则需要长时间的均匀化处理(470 ℃/24h)才能消除组织中的第二相。基于热压缩实验,构建了退火态和均匀化态PMC合金的变形激活能图和热加工图,确定了PMC合金的最佳热变形参数。变形温度为380℃-450℃,可作为退火态和均匀化态PMC合金最佳变形工艺参数。动态软化机制在该条件下为连续动态再结晶。同样,变形温度为350 ℃-380 ℃,应变速率为0.005 s-1-0.17 s-1也可作为退火态合金的最佳变形工艺参数,该条件下粒子促进形核(particle stimulated nucleation,PSN)动态再结晶为主导,同时也伴有连续动态再结晶的发生。热轧过程中,TRC合金条带和PMC合金主要再结晶机制为原始晶界附近逐渐晶格旋转的连续动态再结晶,这类再结晶取向与变形基体取向相似,这也造成了轧制变形后,热轧TRC条带和PMC条带仍具有较强的轧制织构。轧制前450℃/1h退火处理后的TRC条带和轧制前400 ℃/1h退火处理后的PMC合金在热轧过程中第二相粒子激发了 PSN动态再结晶,这类再结晶晶粒在粒子周围形成且呈现出随机的晶体取向。轧制前450 ℃/1h和480 ℃/1h退火处理后的TRC条带经过热轧、冷轧及固溶+预时效+自然时效(ST+PA+NA)热处理后,组织中形成了大量细小均匀的等轴晶,TRC薄带的织构主要为轧制织构和再结晶织构。两种TRC薄带具有相似的晶粒组织形貌和织构取向。轧制前450℃/1h退火处理的TRC条带中含有更多的第二相粒子,然而在轧制变形及ST+PA+NA热处理过程中,PSN作用的再结晶对TRC薄带的组织及织构影响较小。PSN作用的再结晶对PMC合金的组织及织构影响显著。轧制前400℃/1h退火处理后的PMC合金经过热轧、冷轧及ST+PA+NA热处理后,粒子促进了再结晶的发生,形成了大量均匀细小的等轴晶,同时PSN再结晶弱化了PMC薄带的织构。因此,提高了PMC薄带与轧制方向成45°方向和垂直于轧制方向上的拉伸性能,增加了 r值同时降低了Δ 值,改善了 PMC薄带的力学性能各向异性。对比TRC冷轧薄带,轧制前采用480℃/1h退火处理后的TRC冷轧薄带获得了最佳的拉伸性能,其沿轧制方向上的拉伸性能达到了Rp0.2=443 MPa,Rm=600 MPa和δ=1 7.8%。与PMC合金轧制工艺相比,TRC合金轧制工艺流程更短,且获得了与PMC薄带相当的力学性能。本论文通过双辊铸轧技术及后续轧制工艺,缩短了 Al-Zn-Mg-Cu合金板材生产流程,同时控制变形前组织中的第二相粒子,改善了传统铸造Al-Zn-Mg-Cu合金力学性能各向异性问题,为汽车用低成本Al-Zn-Mg-Cu合金板材的制备及组织调控奠定基础。
Abstract
jin xie nian ,neng yuan kui fa 、quan qiu qi hou bian nuan deng neng yuan yu huan jing wen ti ri yi yan jun ,zhi zai jie neng jian pai de qi che qing liang hua xian de yu fa chong yao 。mu qian ,lv ge jin zai qi che qing liang hua cai liao zhong reng zhan ju chong yao de wei 。gao jiang du Al-Zn-Mg-Cuge jin ye bei ying yong yu qi che qing liang hua cai liao shang ,qi che jie gou jian yi gao xing neng lv dai gang shi shi xian qi che qing liang hua de yi chong you xiao tu jing 。tong shi qi che qing liang hua cai liao de zhi bei ye xu man zu lu se zhi zao 、kuai su zhi zao 、you zhi zhi zao de mu biao 。shuang gun zhu ga ji shu (Twin roll casting,TRC)ke you xiao su duan lv ge jin ban cai zhi bei liu cheng ,jian shao neng hao he jiang di cheng ben 。ran er Al-Zn-Mg-Cuge jin de ge jin yuan su han liang gao 、jiang du da ,yong TRCji shu zhi bei reng cun zai yi ding de kun nan 。ben lun wen gen ju TRCgong yi de te dian ,tong shi wei le di gao ge jin jiang du ,she ji le gao Znhan liang de Al-7.9Zn-2.7Mg-2.0Cu(wt.%)ge jin ,zhi ding le TRC+tui huo chu li +ga zhi de gong yi liu cheng 。tong guo dui bi yan jiu TRCge jin he jin shu xing zhu zao (Permanent mold casting,PMC)ge jin de zu zhi yi ji TRChe PMCge jin ga zhi bian xing hou ge jin bao dai de zu zhi he li xue xing neng ,tan jiu le TRCgong yi zhi bei gao Znhan liang Al-Zn-Mg-Cuge jin de ke hang xing 。ji yu kuai su zhi zao de li nian ,li yong tui huo chu li diao kong ge jin ning gu guo cheng zhong xing cheng de di er xiang li zi ,yan jiu le hou xu ga zhi guo cheng zhong di er xiang li zi dui ge jin zai jie jing hang wei de ying xiang ji li 。cong er da dao kong zhi ga zhi bao dai zu zhi he zhi gou ,jiang di ge jin bao dai su xing ge xiang yi xing de mu de 。ben wen cai yong shuang gun zhu ga ji shu cheng gong zhi bei le kuan du wei 130mm,hou du wei 5.5mmde A1-7.9Zn-2.7Mg-2.0Cuge jin tiao dai ,que ding le qi shi jiao zhu wen du wei 690 ℃、zhu ga su du wei 2.36～2.54 m/minhe ga gun jian jian xi wei 4.0mmde zhu ga gong yi can shu 。TRCtiao dai zu zhi cheng xian chu jun yun de deng zhou shu zhi jing ju er ci zhi jing jian ju xi xiao ,zai zhi jing jian xing cheng le xi xiao de Mg(Zn,Al,Cu)2xiang 。duan shi jian de tui huo chu li (480 ℃/1h)ji ke you xiao de xiao chu TRCzu zhi zhong de di er xiang 。ran er ,PMCge jin zhu ding zhong di er xiang che cun jiao da 。jing guo 400℃/1htui huo chu li ,da bu fen de di er xiang reng bao liu zai zu zhi zhong ,PMCge jin ze xu yao chang shi jian de jun yun hua chu li (470 ℃/24h)cai neng xiao chu zu zhi zhong de di er xiang 。ji yu re ya su shi yan ,gou jian le tui huo tai he jun yun hua tai PMCge jin de bian xing ji huo neng tu he re jia gong tu ,que ding le PMCge jin de zui jia re bian xing can shu 。bian xing wen du wei 380℃-450℃,ke zuo wei tui huo tai he jun yun hua tai PMCge jin zui jia bian xing gong yi can shu 。dong tai ruan hua ji zhi zai gai tiao jian xia wei lian xu dong tai zai jie jing 。tong yang ,bian xing wen du wei 350 ℃-380 ℃,ying bian su lv wei 0.005 s-1-0.17 s-1ye ke zuo wei tui huo tai ge jin de zui jia bian xing gong yi can shu ,gai tiao jian xia li zi cu jin xing he (particle stimulated nucleation,PSN)dong tai zai jie jing wei zhu dao ,tong shi ye ban you lian xu dong tai zai jie jing de fa sheng 。re ga guo cheng zhong ,TRCge jin tiao dai he PMCge jin zhu yao zai jie jing ji zhi wei yuan shi jing jie fu jin zhu jian jing ge xuan zhuai de lian xu dong tai zai jie jing ,zhe lei zai jie jing qu xiang yu bian xing ji ti qu xiang xiang shi ,zhe ye zao cheng le ga zhi bian xing hou ,re ga TRCtiao dai he PMCtiao dai reng ju you jiao jiang de ga zhi zhi gou 。ga zhi qian 450℃/1htui huo chu li hou de TRCtiao dai he ga zhi qian 400 ℃/1htui huo chu li hou de PMCge jin zai re ga guo cheng zhong di er xiang li zi ji fa le PSNdong tai zai jie jing ,zhe lei zai jie jing jing li zai li zi zhou wei xing cheng ju cheng xian chu sui ji de jing ti qu xiang 。ga zhi qian 450 ℃/1hhe 480 ℃/1htui huo chu li hou de TRCtiao dai jing guo re ga 、leng ga ji gu rong +yu shi xiao +zi ran shi xiao (ST+PA+NA)re chu li hou ,zu zhi zhong xing cheng le da liang xi xiao jun yun de deng zhou jing ,TRCbao dai de zhi gou zhu yao wei ga zhi zhi gou he zai jie jing zhi gou 。liang chong TRCbao dai ju you xiang shi de jing li zu zhi xing mao he zhi gou qu xiang 。ga zhi qian 450℃/1htui huo chu li de TRCtiao dai zhong han you geng duo de di er xiang li zi ,ran er zai ga zhi bian xing ji ST+PA+NAre chu li guo cheng zhong ,PSNzuo yong de zai jie jing dui TRCbao dai de zu zhi ji zhi gou ying xiang jiao xiao 。PSNzuo yong de zai jie jing dui PMCge jin de zu zhi ji zhi gou ying xiang xian zhe 。ga zhi qian 400℃/1htui huo chu li hou de PMCge jin jing guo re ga 、leng ga ji ST+PA+NAre chu li hou ,li zi cu jin le zai jie jing de fa sheng ,xing cheng le da liang jun yun xi xiao de deng zhou jing ,tong shi PSNzai jie jing ruo hua le PMCbao dai de zhi gou 。yin ci ,di gao le PMCbao dai yu ga zhi fang xiang cheng 45°fang xiang he chui zhi yu ga zhi fang xiang shang de la shen xing neng ,zeng jia le rzhi tong shi jiang di le Δ zhi ,gai shan le PMCbao dai de li xue xing neng ge xiang yi xing 。dui bi TRCleng ga bao dai ,ga zhi qian cai yong 480℃/1htui huo chu li hou de TRCleng ga bao dai huo de le zui jia de la shen xing neng ,ji yan ga zhi fang xiang shang de la shen xing neng da dao le Rp0.2=443 MPa,Rm=600 MPahe δ=1 7.8%。yu PMCge jin ga zhi gong yi xiang bi ,TRCge jin ga zhi gong yi liu cheng geng duan ,ju huo de le yu PMCbao dai xiang dang de li xue xing neng 。ben lun wen tong guo shuang gun zhu ga ji shu ji hou xu ga zhi gong yi ,su duan le Al-Zn-Mg-Cuge jin ban cai sheng chan liu cheng ,tong shi kong zhi bian xing qian zu zhi zhong de di er xiang li zi ,gai shan le chuan tong zhu zao Al-Zn-Mg-Cuge jin li xue xing neng ge xiang yi xing wen ti ,wei qi che yong di cheng ben Al-Zn-Mg-Cuge jin ban cai de zhi bei ji zu zhi diao kong dian ding ji chu 。
论文参考文献
论文详细介绍
论文作者分别是来自山东大学的臧千昊，发表于刊物山东大学2019-07-16论文，是一篇关于合金论文,双辊铸轧论文,粒子促进形核论文,动态再结晶论文,织构论文,山东大学2019-07-16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，资料来自山东大学2019-07-16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。