本文主要研究内容
作者周王凡（2019）在《激光冲击诱导梯度微观组织结构形成机制与力学性能研究》一文中研究指出：金属材料表层的微观结构决定了其使用性能和寿命。表面强力塑性变形方法可以在不引入其他元素的前提下,实现金属材料微结构的多级构筑,使材料的微观结构沿深度方向上呈梯度分布,获得优异的强度-塑性匹配。激光冲击强化通过在材料表层引入残余压应力并改变表层微观组织,提高材料的疲劳寿命,改善摩擦磨损等性能。国内外学者针对各种材料,对激光冲击的强化效果和机理进行了大量研究,并开发了多种外场辅助的激光冲击强化方法。然而,对于激光冲击诱导金属材料超高应变率塑性变形和微观组织特征以及梯度结构的形成和塑性变形机理仍缺乏深入的认识。本文以不同晶格结构的金属材料为对象,系统研究了激光冲击后材料表面完整性变化、梯度层微观组织特征,并通过多尺度仿真模型的建立,研究了超高应变率下位错的演化和塑性变形的特征,基于实验和仿真,研究了激光冲击诱导梯度结构的协同强化行为,主要研究内容和结果如下:激光冲击试样表面完整性变化:使用扫描显微镜、显微硬度仪和纳米压痕、X射线衍射系统研究了激光冲击诱导不同材料表面宏微观形貌,表层残余应力和硬度分布,结果表明:激光冲击处理会造成精磨试样表面粗糙的升高,但表面粗糙度随激光能量和冲击次数的提高变化不大;增加激光能量和冲击次数可以在提高试样表层残余压应力和微观硬度的同时加深残余压应力和硬化层深度;基于纳米压痕测试提出了一种计算激光冲击诱导位错密度的方法;对激光冲击后试样表层衍射峰的定量分析表明,激光冲击能够诱导纯镍和纯铁试样表面产生纳米化。激光冲击诱导梯度层微观组织特征及晶粒细化机理:使用透射电镜系统分析了不同晶格材料激光冲击诱导梯度层的微观组织特征,并基于电镜观测提出了激光冲击诱导高层错金属的晶粒细化机制,结果表明:面心立方纯镍和体心立方纯铁在激光冲击作用下的晶粒细化具有基本相似过程,主要包括:位错大量增殖并逐渐向位错缠结或位错墙转变;原始粗晶被位错缠结或位错墙分割,形成位错胞;塑性变形的增加导致位错胞被压缩以及位错不断向位错胞壁和位错墙聚集,位错胞壁和位错墙逐渐转变为亚晶界和晶界,形成片层晶结构;进一步的塑性应变导致位错墙转变成垂直于片层晶晶界的纵向晶界,超细片层晶逐渐细化成接近等轴的超细晶;随着塑性变形的持续累积,晶内的高密度位错不断向位错墙、亚晶界转变,同时位错在亚晶界处持续湮灭,小角度晶界转变为大角度晶界,最终形成了大角度等轴的纳米晶;在激光冲击过程中Ti-6Al-4V合金α相内的孪生可能仅在变形初期起到调节塑性变形的作用,主导塑性变形的依旧是位错机制。激光冲击过程的多尺度模拟仿真模型:建立了激光冲击过程的位错动力学模型和有限元模型,研究了激光冲击过程中位错演化特征以及激光冲击参数对强化效果的影响,结果表明:在激光诱导超高应变率条件下,纯镍的位错密度随着温度的上升而提高,而纯铁的位错密度随着温度的上升而降低;由位错主导的单晶体塑性变形对温度、加载方向、应变率、位错阻尼系数以及初始位错密度敏感;激光冲击诱导的超高应变率可以有效促进位错的增殖并抑制位错的湮灭,在同等应变下大幅提高位错密度。有限元模拟可以很好地预测次表层中的残余应力和等效塑性应变分布,但无法准确确定表面的残余应力和等效塑性应变;激光光斑尺寸或搭接率的增加可以提高残余压应力层深度,而减小激光光斑尺寸或增加搭接率可以使残余压应力和等效塑性应变分布更均匀;材料应变硬化模量越大,激光冲击诱导残余压应力层的深度越大,弹性模量越大,等效塑性应变和塑性变形层的深度越低;模拟与实验结果的对比表明,有限元方法能够有效地预测低能量激光冲击诱导的残余应力分布,但对于高能量激光冲击,有限元方法有一定的局限性;激光冲击处理可以在低应变和小应变梯度下诱导金属材料产生纳米化。激光冲击诱导梯度结构的塑性变形机理:使用MTS万能试样测试机对激光冲击处理前后的纯镍和纯铁试样进行了准静态拉伸试验,研究了激光冲击参数和梯度层体积分数对拉伸性能的影响,结果表明:激光冲击次数的增加可以提高试样的屈服强度,但伸长率随着冲击次数的增加而降低;激光冲击处理后,随着试样厚度的降低,屈服强度明显增加,但伸长率明显降低;通过控制激光冲击参数可以实现试样比较优异的强度-塑性匹配;厚度的变化不会引起纯镍试样颈缩方式的变化,但是纯铁试样的颈缩方式受试样厚度影响显著;激光冲击诱导的梯度结构具有明显的协同强化效应,协同强化效应源于拉伸过程中,单轴应力向双轴应力的转变以及梯度层与粗晶层之间的应力与应变梯度。
Abstract
jin shu cai liao biao ceng de wei guan jie gou jue ding le ji shi yong xing neng he shou ming 。biao mian jiang li su xing bian xing fang fa ke yi zai bu yin ru ji ta yuan su de qian di xia ,shi xian jin shu cai liao wei jie gou de duo ji gou zhu ,shi cai liao de wei guan jie gou yan shen du fang xiang shang cheng ti du fen bu ,huo de you yi de jiang du -su xing pi pei 。ji guang chong ji jiang hua tong guo zai cai liao biao ceng yin ru can yu ya ying li bing gai bian biao ceng wei guan zu zhi ,di gao cai liao de pi lao shou ming ,gai shan ma ca mo sun deng xing neng 。guo nei wai xue zhe zhen dui ge chong cai liao ,dui ji guang chong ji de jiang hua xiao guo he ji li jin hang le da liang yan jiu ,bing kai fa le duo chong wai chang fu zhu de ji guang chong ji jiang hua fang fa 。ran er ,dui yu ji guang chong ji you dao jin shu cai liao chao gao ying bian lv su xing bian xing he wei guan zu zhi te zheng yi ji ti du jie gou de xing cheng he su xing bian xing ji li reng que fa shen ru de ren shi 。ben wen yi bu tong jing ge jie gou de jin shu cai liao wei dui xiang ,ji tong yan jiu le ji guang chong ji hou cai liao biao mian wan zheng xing bian hua 、ti du ceng wei guan zu zhi te zheng ,bing tong guo duo che du fang zhen mo xing de jian li ,yan jiu le chao gao ying bian lv xia wei cuo de yan hua he su xing bian xing de te zheng ,ji yu shi yan he fang zhen ,yan jiu le ji guang chong ji you dao ti du jie gou de xie tong jiang hua hang wei ,zhu yao yan jiu nei rong he jie guo ru xia :ji guang chong ji shi yang biao mian wan zheng xing bian hua :shi yong sao miao xian wei jing 、xian wei ying du yi he na mi ya hen 、Xshe xian yan she ji tong yan jiu le ji guang chong ji you dao bu tong cai liao biao mian hong wei guan xing mao ,biao ceng can yu ying li he ying du fen bu ,jie guo biao ming :ji guang chong ji chu li hui zao cheng jing mo shi yang biao mian cu cao de sheng gao ,dan biao mian cu cao du sui ji guang neng liang he chong ji ci shu de di gao bian hua bu da ;zeng jia ji guang neng liang he chong ji ci shu ke yi zai di gao shi yang biao ceng can yu ya ying li he wei guan ying du de tong shi jia shen can yu ya ying li he ying hua ceng shen du ;ji yu na mi ya hen ce shi di chu le yi chong ji suan ji guang chong ji you dao wei cuo mi du de fang fa ;dui ji guang chong ji hou shi yang biao ceng yan she feng de ding liang fen xi biao ming ,ji guang chong ji neng gou you dao chun nie he chun tie shi yang biao mian chan sheng na mi hua 。ji guang chong ji you dao ti du ceng wei guan zu zhi te zheng ji jing li xi hua ji li :shi yong tou she dian jing ji tong fen xi le bu tong jing ge cai liao ji guang chong ji you dao ti du ceng de wei guan zu zhi te zheng ,bing ji yu dian jing guan ce di chu le ji guang chong ji you dao gao ceng cuo jin shu de jing li xi hua ji zhi ,jie guo biao ming :mian xin li fang chun nie he ti xin li fang chun tie zai ji guang chong ji zuo yong xia de jing li xi hua ju you ji ben xiang shi guo cheng ,zhu yao bao gua :wei cuo da liang zeng shi bing zhu jian xiang wei cuo chan jie huo wei cuo qiang zhuai bian ;yuan shi cu jing bei wei cuo chan jie huo wei cuo qiang fen ge ,xing cheng wei cuo bao ;su xing bian xing de zeng jia dao zhi wei cuo bao bei ya su yi ji wei cuo bu duan xiang wei cuo bao bi he wei cuo qiang ju ji ,wei cuo bao bi he wei cuo qiang zhu jian zhuai bian wei ya jing jie he jing jie ,xing cheng pian ceng jing jie gou ;jin yi bu de su xing ying bian dao zhi wei cuo qiang zhuai bian cheng chui zhi yu pian ceng jing jing jie de zong xiang jing jie ,chao xi pian ceng jing zhu jian xi hua cheng jie jin deng zhou de chao xi jing ;sui zhao su xing bian xing de chi xu lei ji ,jing nei de gao mi du wei cuo bu duan xiang wei cuo qiang 、ya jing jie zhuai bian ,tong shi wei cuo zai ya jing jie chu chi xu yan mie ,xiao jiao du jing jie zhuai bian wei da jiao du jing jie ,zui zhong xing cheng le da jiao du deng zhou de na mi jing ;zai ji guang chong ji guo cheng zhong Ti-6Al-4Vge jin αxiang nei de luan sheng ke neng jin zai bian xing chu ji qi dao diao jie su xing bian xing de zuo yong ,zhu dao su xing bian xing de yi jiu shi wei cuo ji zhi 。ji guang chong ji guo cheng de duo che du mo ni fang zhen mo xing :jian li le ji guang chong ji guo cheng de wei cuo dong li xue mo xing he you xian yuan mo xing ,yan jiu le ji guang chong ji guo cheng zhong wei cuo yan hua te zheng yi ji ji guang chong ji can shu dui jiang hua xiao guo de ying xiang ,jie guo biao ming :zai ji guang you dao chao gao ying bian lv tiao jian xia ,chun nie de wei cuo mi du sui zhao wen du de shang sheng er di gao ,er chun tie de wei cuo mi du sui zhao wen du de shang sheng er jiang di ;you wei cuo zhu dao de chan jing ti su xing bian xing dui wen du 、jia zai fang xiang 、ying bian lv 、wei cuo zu ni ji shu yi ji chu shi wei cuo mi du min gan ;ji guang chong ji you dao de chao gao ying bian lv ke yi you xiao cu jin wei cuo de zeng shi bing yi zhi wei cuo de yan mie ,zai tong deng ying bian xia da fu di gao wei cuo mi du 。you xian yuan mo ni ke yi hen hao de yu ce ci biao ceng zhong de can yu ying li he deng xiao su xing ying bian fen bu ,dan mo fa zhun que que ding biao mian de can yu ying li he deng xiao su xing ying bian ;ji guang guang ban che cun huo da jie lv de zeng jia ke yi di gao can yu ya ying li ceng shen du ,er jian xiao ji guang guang ban che cun huo zeng jia da jie lv ke yi shi can yu ya ying li he deng xiao su xing ying bian fen bu geng jun yun ;cai liao ying bian ying hua mo liang yue da ,ji guang chong ji you dao can yu ya ying li ceng de shen du yue da ,dan xing mo liang yue da ,deng xiao su xing ying bian he su xing bian xing ceng de shen du yue di ;mo ni yu shi yan jie guo de dui bi biao ming ,you xian yuan fang fa neng gou you xiao de yu ce di neng liang ji guang chong ji you dao de can yu ying li fen bu ,dan dui yu gao neng liang ji guang chong ji ,you xian yuan fang fa you yi ding de ju xian xing ;ji guang chong ji chu li ke yi zai di ying bian he xiao ying bian ti du xia you dao jin shu cai liao chan sheng na mi hua 。ji guang chong ji you dao ti du jie gou de su xing bian xing ji li :shi yong MTSmo neng shi yang ce shi ji dui ji guang chong ji chu li qian hou de chun nie he chun tie shi yang jin hang le zhun jing tai la shen shi yan ,yan jiu le ji guang chong ji can shu he ti du ceng ti ji fen shu dui la shen xing neng de ying xiang ,jie guo biao ming :ji guang chong ji ci shu de zeng jia ke yi di gao shi yang de qu fu jiang du ,dan shen chang lv sui zhao chong ji ci shu de zeng jia er jiang di ;ji guang chong ji chu li hou ,sui zhao shi yang hou du de jiang di ,qu fu jiang du ming xian zeng jia ,dan shen chang lv ming xian jiang di ;tong guo kong zhi ji guang chong ji can shu ke yi shi xian shi yang bi jiao you yi de jiang du -su xing pi pei ;hou du de bian hua bu hui yin qi chun nie shi yang geng su fang shi de bian hua ,dan shi chun tie shi yang de geng su fang shi shou shi yang hou du ying xiang xian zhe ;ji guang chong ji you dao de ti du jie gou ju you ming xian de xie tong jiang hua xiao ying ,xie tong jiang hua xiao ying yuan yu la shen guo cheng zhong ,chan zhou ying li xiang shuang zhou ying li de zhuai bian yi ji ti du ceng yu cu jing ceng zhi jian de ying li yu ying bian ti du 。
论文参考文献
论文详细介绍
论文作者分别是来自江苏大学的周王凡，发表于刊物江苏大学2019-09-19论文，是一篇关于激光冲击强化论文,表面完整性论文,纳米化论文,梯度结构论文,位错动力学论文,有限元论文,力学性能论文,江苏大学2019-09-19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，资料来自江苏大学2019-09-19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：激光冲击强化论文; 表面完整性论文; 纳米化论文; 梯度结构论文; 位错动力学论文; 有限元论文; 力学性能论文; 江苏大学2019-09-19论文;