共查询到19条相似文献,搜索用时 114 毫秒
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在Ti6Al4V合金表面电镀适当厚度的纳米纯镍,是提高其表面强度和耐磨性的一种行之有效的方法.作为一种整体结构件,在实际应用中镍硬化层的厚度对部件的内应力分布以及尺寸稳定性有着重要的影响.为确定钛合金表面镍硬化层的合适厚度,利用纳米显微力学探针测量了材料的弹性模量,采用ANSYS有限元软件,对钛合金表面电镀纳米镍硬化层在受压情况下的应力分布进行了分析,并以此对纳米镍硬化层的厚度进行了模拟设计.研究表明:当电镀纳米镍硬化层厚度在0.25~1.25 mm范围时,最大等效应力发生在钛合金和镍之间,容易引起界面处裂纹的产生;合适的电镀纳米镍硬化层厚度范围应在1.25~2.5 mm,最佳厚度约为2 mm. 相似文献
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目的为了改善45钢表面状态,提高其表面性能,采用CO2激光器对其表面进行激光相变硬化处理。方法利用带有能谱的扫描电子显微镜(SEM/EDS)、盐雾试验机等,对激光相变硬化层组织及耐蚀性能进行了观察和分析。结果激光相变硬化层由熔化区、相变硬化区和热影响区三部分组成,其组织依次为:混合马氏体+未溶碳化物、针状马氏体、残余奥氏体。随扫描速度增加,耐蚀性先变好而后变差。结论激光相变硬化处理可改善45钢的表面性能,显著提高其耐蚀性能。 相似文献
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常压等离子束扫描表面多元共渗研究 总被引:2,自引:0,他引:2
用高参等离子束在常压下快速扫描涂敷合金渗剂的45^#钢管内表面,可实现多元共渗及自激冷淬火,获得多元共渗及淬火硬化层。用电子探针和透射电镜对硬化层的成分和组织结构进行分析,结果表明,渗剂中所含硼、硅、铈三种元素以不同深度渗入材料内部,硬层为隐针马氏体及硼硅化合物。经检测,硬化层具有较高的硬度及合理的硬度梯度,具有优异的耐磨性及良好的耐蚀性。 相似文献
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对ZGMn13Cr2钢表面进行一次爆炸处理,测量其冲击磨损性能,观察不同硬化层的显微组织,分析其硬化机理。实验结果表明:经爆炸处理后的ZGMn13Cr2钢硬度随硬化深度的增加而降低,耐磨性提高了1.32~1.41倍,磨损形貌以犁沟、剥落坑为主,还有少量破碎坑;通过对不同硬化深度的实验用钢表面进行显微表征,发现硬化层内产生了大量的形变孪晶,爆炸表面具有高密度位错的畴界,距爆炸表面10 mm处有泰勒晶格以及距爆炸表面20 mm处出现大量平行的滑移带和滑移带交割,未观察到马氏体组织,仍以基体奥氏体为主,这说明一次爆炸处理的ZGMn13Cr2钢的硬化机理为孪晶硬化和位错硬化的复合机制。 相似文献
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由于光纤激光的良好光束质量,光纤激光器在金属材料表面强化方面的应用日益引起学者的重视。使用YLS-3000W光纤激光器对Cr12MoV冷作模具钢进行激光表面淬火处理的工艺试验,研究了不同工艺参数对硬化层深度和显微硬度的影响及硬化层显微组织特征。结果表明,Cr12MoV表面经光纤激光表面淬火后得到淬火层、过渡层和基体3层不同的组织。淬火层的晶粒细小,由隐晶马氏体、弥散分布的碳化物组成。过渡层由马氏体及弥散分布的碳化物和残留奥氏体组成。在扫描速度和离焦量一定的条件下,相变硬化层深度随光纤激光功率的增大而增加。在最佳工艺(光纤激光功率900W,扫描速度0.3m/s,离焦量-4mm)条件下,硬化层平均硬度达609HV。分析认为光纤激光淬火造成的组织细化和过饱和的隐晶马氏体的形成是硬度提高的主要原因。 相似文献
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采用热磁分析、显微硬度分析与直读光谱分析等相结合的方法,对无碳化物贝氏体钢进行渗碳后的深冷处理工艺优化。结果表明:无碳化物贝氏体钢在1193K渗碳空冷后,测试有效硬化层样品的热磁曲线,可以得到有效硬化层的深冷处理温度宜低于134K。经123K深冷处理和463K回火,有效硬化层残留奥氏体含量约为12.2%(质量分数)。通过深冷处理使渗碳钢近表面层得到显著硬化,再经低温回火使近表面层硬度均达到810HV_(1.0)左右,渗碳钢的硬度梯度分布趋于合理。 相似文献
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《Current Opinion in Solid State & Materials Science》2014,18(1):19-28
Experimental results indicate that metal–ceramic multilayered thin films have unusual properties such as high strength, measurable plasticity and high strain hardening rate when both layers are nanoscale. Furthermore, the strength and strain hardening rate show a pronounced size effect, depending not only on the layer thickness but also on the layer thickness ratio. We analyze the strain hardening behavior of nanoscale multilayers using a three-dimensional crystal elastic–plastic model (3DCEPM) that describes plastic deformation based on the evolution of dislocation density in metal and ceramic layers according to confined layer slip mechanism. These glide dislocations nucleate at interfaces, glide inside layers and are deposited at interfaces that impede slip transmission. The high strain hardening rate is ascribed to the closely spaced dislocation arrays deposited at interfaces and the load transfer that is related to the layer thickness ratio of metal and ceramic layers. The measurable plasticity implies the plastically deformable ceramic layer in which the dislocation activity is facilitated by the interaction force among the deposited dislocations within interface and in turn is strongly related to the ceramic layer thickness. 相似文献
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A bifurcation analysis of a layered ductile structural element undergoing homogeneous, high-rate extension is presented. Formation
of multiple strain localization sites provides a precursor to ductile fragmentation, and the objective of the analysis is
to investigate the effect of an added surface layer on resistance of the structural element to fragmentation. The analysis
shows that, in addition to dissipating plastic work, the outer layer can increase the total energy dissipation prior to fragmentation
by increasing bifurcation strain. The analysis also shows that the strain hardening exponent of the outer layer plays an important
role in increasing the bifurcation strain; higher values of hardening exponent result in higher bifurcation strain. Strength
and density of the outer layer play a secondary role in increasing bifurcation strain. Once a material with a high hardening
exponent is chosen for the outer material, its strength plays an important role in increasing the total dissipated energy.
The analysis also reveals that, for certain combinations of strength and hardening exponent of the outer layer, the sandwich
structure can dissipate more energy than a homogeneous core structure of the same total thickness and length. This is so even
when the outer layer is weaker than the core. Energy dissipated per unit mass can be significantly improved by choosing a
softer outer layer which displays high-strain hardening. Thus, the bifurcation analysis presented here provides a quantitative
guideline for material selection in designing layered structures optimized for resistance to fragmentation. 相似文献
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激光扫描速度对40Cr钢表面组织结构的影响 总被引:3,自引:0,他引:3
对调质态的40Cr钢试样用CO2连续波输出激光速进行相变硬化处理,用穆斯堡尔谱学方法研究了激光扫描速度对试样表面层组织结构的影响,结果表明,40Cr钢激光硬化层的组织为马氏体,残余奥氏体和少量未溶碳化物。随激光扫描速度增大,试样中的马氏体和未溶碳化物的含量不断增加,残余奥氏体含量则连续下降。 相似文献
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对奥氏体不锈钢表面进行了爆炸强化、滚压强化和喷丸强化。爆炸强化时表面层内出现形变孪晶栅栏,位错线具有方向性、呈密布排列,局部山现ε马氏体、α马氏体和奥氏体超细晶粒的区域;滚压强化后表面层内也有就、孪晶栅栏出现,但位错以胞状结构的形式分布在奥氏体基体上;喷丸强化的表面层内孪晶栅栏十分致密,位错线仍以方向性排布,并无位错胞出现。表面层内组织结构出现差异,主要与变形速度和变形量有关,高速和较大的变形量可诱发α,ε马氏体转变和形成超细奥氏体晶粒,慢速变形时能促使位错胞的形成。本文还讨论了孪晶栅栏的形成方式及其内部构造。 相似文献
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20CrV钢机用锯条齿部表面强化组织的研究 总被引:11,自引:0,他引:11
本文介绍了20CrV钢机用锯条经渗金属、渗碳、淬火及回火的表面强化处理工艺,并对强化后锯条齿部碳化物、相结构进行了组织分析和X射线检测。研究结果表明,齿部组织状态及相结构已接近高速钢,经切削试验,性能达到高速钢要求。 相似文献
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D. V. Pavlenko S. V. Loskutov V. K. Yatsenko N. V. Gonchar 《Technical Physics Letters》2003,29(4):345-346
Experimental data showing variation of the mechanical properties of the surface layer of a nickel-based EK79-ID alloy depending
on the degree of surface straining are presented. The elastic modulus and the proof stress of the surface layer exhibit nonmonotonic
variation with the degree of straining. The possible mechanisms determining changes in the elastic modulus in the course of
the surface structure variation caused by the strain hardening are considered. 相似文献
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V. D. Efremov M. S. Zheludkevich M. L. German 《Journal of Engineering Physics and Thermophysics》2000,73(2):428-435
A mathematical model of heat transfer in steel parts under force grinding is considered that allows one to determine the grinding
parameters at which a steel layer of prescribed thickness is heated up to hardening temperatures. Results of numerical simulation
of the process of hardening grinding are compared with experimental data. The internal structure of the material after hardening
grinding is analyzed.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 430–438, March–April, 2000. 相似文献