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采用淬火膨胀仪进行模拟试验,通过对18CrNiMo7-6钢的显微组织、硬度分布的表征,研究了经真空渗碳后18CrNiMo7-6钢在冷却过程中碳化物的析出规律。结果表明,在980 ℃保温30 min后,试验钢中的碳化物完全溶解;快速冷却至600 ℃保温20 min后,渗层组织充分转变为细片层珠光体形貌组织;再升温至830 ℃保温20 min并以20 ℃/s的冷速气冷至室温后,室温组织出现不同形态的碳化物,马氏体组织较热处理前的原始组织得到了细化,且硬度及淬硬层深度较热处理前显著提升。 相似文献
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本文对17CrNiMo6、18CrNiMo7-6、12Cr2Ni4三种渗碳钢进行四种不同的渗碳淬火工艺,对出现网状碳化物的敏感性进行了试验研究,按国家标准采用金相显微组织分析方法,对碳化物级别进行了检验。结果表明:18CrNiMo7-6钢的网状碳化物敏感性最高,其次是17CrNiMo6钢和12Cr2Ni4钢;820℃淬火后渗碳钢的碳化物级别好于780℃淬火的;二次淬火后渗碳钢的碳化物级别好于一次淬火的。 相似文献
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对新型16Cr3NiWMoVNbE齿轮钢进行渗碳处理,研究了温度、强渗期碳势和扩散期碳势对渗碳层组织及性能的影响。结果表明:随温度的升高,渗碳层的厚度和碳浓度均随之增加,但碳浓度随渗层的深入逐渐下降;在920℃渗碳时,渗层厚度在强渗期碳势1.5%C时达到最大值,碳化物数量和尺寸均随碳势的升高有增多增大的趋势;随扩散期碳势的升高,渗碳层厚度和碳化物数量、尺寸均随之增加,达到1.2%C时,出现角状或断网状碳化物;渗碳温度为920℃,强渗期碳势为1.4%C,扩散期碳势为0.9%C的优化工艺,能够很好的满足技术要求。 相似文献
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对20CrNi2Mo和20Cr2Ni4钢进行渗碳热处理,研究了其微观组织、硬度、抗拉强度和伸长率等性能。结果表明,钢材的表层硬度由表及里逐渐降低,同一深度下,20CrNi2Mo钢的硬度要高于20Cr2Ni4钢。20CrNi2Mo钢渗碳热处理后具有更好的综合性能。 相似文献
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研究了精密气体渗碳等温淬火工艺对18Cr2Ni4WA钢渗层硬度、深度及显微组织的影响。结果表明,随着总渗碳保温时间的延长,渗层深度增加,但硬度曲线变得平缓;在相同总保温时间的情况下,强渗时间越长,渗层越深;而当扩散时间相同时,强渗时间越长,淬火后表层的硬度较低。优化的精密气体渗碳工艺为:保温温度均为910℃,强渗阶段碳势1.20%,保温3 h;扩散阶段碳势0.80%,保温1 h,渗碳后进行等温淬火,可以获得(1.2±0.1)mm渗层深度。渗碳淬火后渗层组织良好。该工艺成功应用于衬套零件的实际生产,满足了设计要求。 相似文献
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《热处理》2016,(2)
对18CrNiMo7-6钢试样分别进行了这样的处理:940℃渗硼5 h,油淬和低温回火;先渗碳至0.5 mm,然后940℃渗硼5 h,油淬和低温回火。采用光学显微镜、扫描电镜、X射线衍射仪和显微硬度计检测了试样渗层的显微组织和硬度,以揭示预渗碳对18CrNiMo7-6钢渗硼的影响。结果表明,单一渗硼的18CrNiMo7-6钢试样渗层厚度为135μm,表面硬度为1 680 HV0.2;而经渗碳-渗硼的18CrNiMo7-6钢试样渗层厚度为150μm,表面硬度为1 710 HV0.2。两种试样的渗层均主要由Fe_2B相和少量FeB相组成。此外,渗碳-渗硼试样的过渡区宽度达1 600μm,远大于单一渗硼试样的过渡区宽度,从而显著改善了硼化物层的承载性能。 相似文献
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模具渗硼工艺及其发展应用 总被引:4,自引:0,他引:4
渗硼是提高模具使用寿命的重要途径,是在金属表面形成高硬度的金属硼化层,显著提高其耐磨性,且具有良好的耐热性和耐蚀性。近年来,随着渗硼工艺逐步改进和完善,已发展了复合渗、多元共渗及低温渗硼工艺,取得了良好的经济效果。 相似文献
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A. A. Babakov 《Metal Science and Heat Treatment》1967,9(10):764-770
Conclusions Highly alloyed steels and alloys are produced in conformity with GOST or technical specifications in thick and thin sheets, beams and channels, bars, hot-rolled and cold-rolled pipe, and rod. Castings are produced in the specialized plant of the Ministry of Chemical and Petroleum Machine Building.The technology of welding stainless steels and alloys is given in [15] and [16].TsNIIChERMET. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 43–50, October, 1967. 相似文献
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A. Yu. Tsivadze G. V. Ionova V. K. Mikhalko 《Protection of Metals and Physical Chemistry of Surfaces》2010,46(2):149-169
The possibility of using unique properties of lanthanides in the nanotechnology is demonstrated. The origination of linear
and nonlinear optical properties of lanthanide compounds with phthalocyanines, porphyrins, naphthalocyanines, and their analogs
in solutions and condensed state and the prospects of obtaining novel materials on their basis are discussed. Based on the
electronic structure and properties of lanthanides and their compounds, namely, optical and magnetic characteristics, electronic
and ionic conductivity, and fluctuating valence, molecular engines are classified. High-speed storage engines or memory storage
engines; photoconversion molecular engines based on Ln(II) and Ln(III); electrochemical molecular engines involving silicate
and phosphate glasses; molecular engines whose operation is based on insulatorsemiconductor, semiconductor-metal, and metal-superconductor
types of conductivity phase transitions; solid electrolyte molecular engines; and miniaturized molecular engines for medical
analysis are distinguished. It is shown that thermodynamically stable nanoparticles of Ln
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M
y
composition can be formed by d elements of the second halves of the series, i.e., those arranged after M = Mn, Tc, and Re.
Prospects of using lanthanide superconductors in nanotechnology are considered. 相似文献
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金刚石、CBN有序排列及择优取向工具的研发及应用 总被引:1,自引:0,他引:1
有序排列/择优取向超硬材料工具的技术创新,将广泛适用于电镀、树脂、陶瓷、金属结合剂制品工具中,使用超硬材料颗粒在结合剂中均匀排列并择优定向,以最大潜能的发挥超硬材料各个方面固有的特性。并针对不同的加工对象,有选择性的使用超硬材料各自不同的特性,从而使超硬材料工具将以经济、高质与高效的优势替代传统的超硬材料工具并将进入新兴的加工领域,为生产企业带来新的发展机遇。本文将对有序排列与择优取向技术的研究现状及其在不同的金刚石工具中的应用做一阐述。 相似文献
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V. Kulikovsky V. Vorlí?ek M. Stranyánek R. ?tvrtlík A. Kurdyumov 《Surface & coatings technology》2008,202(9):1738-1745
Hydrogen-free amorphous and nanocrystalline films were prepared by magnetron sputtering of the SiC or Si targets. Mechanical properties (hardness, elastic modulus, intrinsic stress) and film structures were investigated in dependence on the substrate bias and temperature. It was found that both hardness and elastic modulus of all amorphous a-SiC films prepared at different substrate temperatures and biases are always lower than those for bulk α-SiC single crystal while the hardness of partially crystalline SiC films is higher and the elastic modulus lower than those for α-SiC one. In contrast, both hardness and elastic modulus of all amorphous Si films are always lower than those for nanocrystalline Si films which show approximately the same value as the Si single crystal. 相似文献