共查询到19条相似文献,搜索用时 109 毫秒
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本文利用超声频微锻造机构对45钢激光淬火层表面进行了微锻造处理。利用OM、SEM观察了微锻造对45钢激光淬火层表面组织的影响;利用显微硬度计与洛氏硬度计研究了微锻造后45钢激光淬火层表面显微硬度,硬化深度方向的显微硬度。结果表明:高频微锻造处理后,45钢激光淬火形成的明显而规则马氏体组织被锻碎,表面晶粒明显细化。表面显微硬度提高了11.4%,激光淬火强化区深度方向的显微硬度影响深度为0.2 mm,其中0.1 mm处硬度提高了10.0%,0.2 mm处提高了4.5%。 相似文献
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在不同激光能量(4,6,8 J)下对45钢试样表面进行激光冲击强化,研究了激光能量对试样显微硬度、残余应力、微观结构和摩擦磨损性能的影响。结果表明:随着激光能量的增加,45钢的晶格畸变程度、残余压应力、显微硬度和耐磨性能不断提升。在8 J激光能量下,45钢的表面(211)晶面半高宽、残余压应力和显微硬度分别增加到3.50°,500 MPa, 345 HV,摩擦因数和磨损质量损失分别减小到0.61和157 mg,同时磨损表面剥落物最少,犁沟的深度和宽度最小。45钢摩擦磨损性能的提升与激光冲击强化诱导的高密度位错结构和高幅值残余压应力有关。 相似文献
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激光淬火处理对灰铸铁残余应力与耐磨性能的影响 总被引:3,自引:1,他引:3
利用CO2激光对HT200铸铁进行了表面淬火处理,对其微观显微组织和显微硬度进行了分析,用X-350A型应力测试仪测定了其残余应力和残余奥氏体的分布,并进行了耐磨性试验.结果表明,激光淬火后HT200显微硬度由HV250提高到HV530,表面残余应力均为压应力,其值在-300 MPa以上;耐磨性能明显得到提高,并随残余压应力的增加而增大,将有利于提高HT200材料的使用寿命;激光淬火处理诱发的残余奥氏体有利于抑制裂纹的扩展,提高材料的耐磨性能. 相似文献
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用大功率CO2激光器对CrWMn钢表面进行激光强化处理,对激光淬火层的组织进行了分析,对淬火层的硬度进行了测试。结果表明,激光淬火层组织显著细化,硬度明显高于基体硬度。通过正交试验和极差分析,系统考察了激光强化工艺参数对CrWMn钢基体显微硬度的影响,获得了最佳强化处理工艺参数,并讨论了激光表面强化机理。 相似文献
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模具刃口的激光淬火试验与数值模拟 总被引:1,自引:0,他引:1
以常用的45钢制作的试件模拟模具刃口,对其进行激光淬火试验,试验测量相变区的硬度、深度和宽度,通过硬度值估测淬硬层的深度,并将此深度作为数值模拟的验证依据.建立相应的计算模型,对试验过程进行模拟计算,得到试件在激光淬火后的应力场分布与位移场分布.结果表明:试件在激光淬火后表面硬度达到了模具钢的使用要求,且变形很小,相对试件的几何尺寸可以忽略不计;在热应力和相变应力的共同作用下,试件表层存在较为复杂的残余应力分布,选取合适的激光工艺参数可以达到预期的性能要求;为激光淬火的实际应用提供了参考依据. 相似文献
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大模数齿轮宽带激光淬火 总被引:2,自引:0,他引:2
提出了激光热处理一个新的应用领域——采用宽带激光淬火对大模数齿轮进行表面强化处理,有效地防止齿面大块剥落的失效。试验在几种不同激光淬火工艺下进行,选取最佳工艺,并得出在其工艺处理下的性能及组织特征:硬化层深1.2~1.4mm,宽20mm,表面硬度HRC55~60,心部硬度HRC30~35、硬化层组织为细晶混合马氏体相少量残余奥氏体,心部为细回火索氏体。在整个硬化层中获得较高的残余压应力,其值在267~425MPa之间,并分析讨论了这些特性对防止大模数齿轮失效所起到的有效作用。 相似文献
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文中介绍了激光淬火与氮化处理的两种表面复合处理工艺方案:激光-氮化复合处理和氮化-激光复合处理。以离心式分离机中4Cr13不锈钢碟片为试验材料,用两种不同的工艺方案对4Cr13钢试样进行表面复合强化处理。根据所得硬度分布曲线和硬化层深度比较表,分析了激光淬火与氮化处理的不同组合顺序对材料表面硬化层硬度分布和硬化层深度的综合影响效果,最后得出采用氮化-激光复合处理工艺方案可以达到试样表面复合强化处理工艺要求。 相似文献
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CHEN Ruifang School of Mechanical Engineering Jiangsu University Zhenjiang China HUA Yinqun School of Materials Science Engineering Jiangsu University Zhenjiang China CAI Lan School of Mechanical Engineering Jiangsu University Zhenjiang China 《机械工程学报(英文版)》2007,20(2):52-55
40Cr steel is laser quenched by the NEL-2500A rapidly axial flow CO2 laser. Then the martensite induced by laser quenched is shocked by Nd:YAG laser again. Through comparing and analyzing the appearance and size of martensite,the dislocation density in microstructure between the treated zones by laser quenched and by laser quenched plus laser shock,the following results are shown: The second martensite obtained by laser compound treatment is more finer compared with those obtained by laser quenched; In the hardened zones obtained by compound treatment,a lot of slender second twin crystal martensites are induced; A lot of more high density dislocation tangles and cellular dislocations are generated. From the transmission electron microscope (TEM) micrograph after compound treatment,there are not only long lath and short nubbly martensites arranged in cross direction,but also massive nubbly and small short nubbly martensites arranged in longitudinal direc-tion. Some martensites look like the broken blocks of quenched martensites. These new martensites are inserted transversely in the quenched martensites with large tangle. And they make quenched martensites break into pieces. Compared with the quenched martensites,the size of fresh martensites are smaller,about 0.3~0.5μm. 相似文献
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A. F. M. Arif Bekir Samir Yilbas 《The International Journal of Advanced Manufacturing Technology》2008,37(7-8):698-704
The laser cutting of metallic substrates results in the development of thermal stresses around the cut edges. Depending on
the cutting speed, laser power intensity, and material properties, stress levels reaching and exceeding the yielding limit
of the substrate material can result. In the present study, the laser cutting situation is simulated and temperature as well
as thermal stress fields are computed for steel, Inconel 625, and Ti-6Al-4V alloy. The cutting speed of the laser is considered
to be constant and a constant temperature heat source with a focused spot diameter is assumed along the kerf surface at the
cut edge, resembling the laser heat source. The equations for energy and thermal stresses are solved numerically using the
finite element method (FEM). It is found that the temperature decays sharply in the vicinity of the cut edges and that the
equivalent stress attains high values in this region. Inconel 625 results in the highest thermal stress levels in the vicinity
of the cut edges and is then followed by steel and titanium alloy. 相似文献
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Photoelastic observations of thermal stress were conducted during the separation of glass substrates by thermal stress cleaving with a laser. A polariscope system was built in the laser cleaving system for observation during laser cleaving, and isochromatic and isoclinic fringe patterns were studied to analyze the thermal stress induced by laser irradiation. The proposed method allows for the visualization of stress asymmetry that decreases the process accuracy, and for the detection of crack stagnation which decreases the process reliability. 相似文献
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激光熔覆是利用高能束激光热源辐射熔覆层和基材表面,使之熔化并迅速凝固,从而显著改善基材性能的一种新的工艺方法.由于熔覆层和基材的物理特性不一样,激光熔覆过程中必然产生热应力,其形态表现为拉应力.熔覆层表面在拉应力的作用下出现裂纹,严重影响了试件的质量.通过实验与建模,分析了熔覆层的应力类型,阐明了裂纹的形成机理,同时对试件进行预热和对熔覆层作微锻造处理,从机理和数学模型两个方面,论证了对熔覆层进行微锻造可以减少或消除熔覆层的拉应力,控制裂纹的产生. 相似文献