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S40C钢制齿轮服役一段时间后,单个齿面出现裂纹状缺陷。采用宏微观分析、金相检验、显微硬度测试等方法,对该齿轮缺陷产生的原因进行分析。结果表明:齿面裂纹状缺陷为接触疲劳所致,造成局部接触疲劳裂纹产生的根源是齿面存在磨削烧伤,显著降低齿面硬度,改变齿面强度梯度分布,在循环啮合作用下出现接触疲劳开裂。进一步地,对感应淬火齿轮齿面硬度降低的影响因素进行详尽的阐述,并结合不同啮合状态下齿轮强度曲线和剪切应力曲线之间的相互关系,论述常见的齿轮剥落现象及失效机理。 相似文献
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针对汽车齿轮运行过程中发生断齿现象,运用光学显微镜、扫描电镜观察了齿轮断口的宏观及微观形貌,并对齿轮截面渗碳层硬度分布进行测定。结果表明,在外载作用下,齿轮表面产生应力集中造成齿面次表层局部损伤并出现微裂纹,裂纹扩展以及齿面碾压,造成表面渗层剥落,心部存在的铁素体组织,降低其心部硬度,导致齿轮断裂失效。 相似文献
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发动机传动轴齿轮断裂失效分析 总被引:2,自引:0,他引:2
某发动机累计工作66min后,传动轴齿轮上有两个齿发生了断裂,与其相配合的片齿轮未发现任何损伤.对传动轴齿轮和片齿轮的齿形、齿向进行了检测,结果表明,传动轴齿轮和片齿轮的齿形和齿向参数符合技术要求.对传动轴断齿的宏微观特征进行了观察与分析,并对传动轴和片齿轮的渗层深度、金相组织进行了检测.结果表明,传动轴断齿的断裂性质为疲劳断裂,传动轴齿表面硬度偏低和片齿轮表面硬度偏高导致传动轴齿表面接触疲劳剥落,传动轴齿轮表面渗层出现的连续网状氮化物是促进其疲劳断裂的又一个影响因素.建议完善传动轴和片齿轮的表面处理工艺参数,加强控制工艺过程. 相似文献
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Shaopeng Wei Gang Wang Xianhui Zhao Xiaopeng Zhang Yiming Rong 《Journal of Materials Engineering and Performance》2014,23(2):545-550
As a low-carbon alloy steel, 20Cr2Ni4A steel has an excellent mechanical properties. It has been used for producing heavy-duty gears, which require good wear and fatigue resistance. The vacuum carburizing process can improve the quality of gears and extend the service life. In this article, a complete heat-treatment process for 20Cr2Ni4A, with carburizing, tempering, quenching and cryogenic steps involved, was proposed. A numerical method was employed to design the carburizing step. The carburized samples were characterized by analysis of carbon profile, surface-retained austenite content, microstructure, and hardness profile. A good microstructure was obtained with acicular-tempered martensite, less-retained austenite, fine granular-dispersed carbides, and was oxide free. The final surface hardness was 64.2HRC, and the case depth was 0.86 mm, which meet the requirements of products. The relationships among process, performance, and microstructure were investigated to understand the inner connection. 相似文献
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Highly-loaded transmission components like gears are case hardened for most applications to reach a load adapted strength. The surface layer microstructure as a function of heat treatment decisively determines the achievable load-bearing properties of the component as well as the technological limits of gear grinding. Against this background, this paper deals with the machinability (discontinuous profile grinding) of differently (carburizing and carbonitriding) case-hardened gears with various multi-phase microstructures and improved load-carrying capacity. Therefore, effects of different material phases, precipitates and their distribution in the surface layer on the gear-grinding process will be discussed. 相似文献
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The effects of forging parameters on the deformation and microstructure distributions of as-forged straight spur gears were investigated by finite element (FE) simulation and statistical analysis method. Spur gear forging using the movable cavity die design was investigated by integrating the FE method with the microstructure evolution models for AZ31B magnesium alloys. The required inputs such as flow stress curves and microstructure evolution models, were obtained through the Gleeble thermal mechanical testing and quantitative metallography analysis method. Numerical simulation and experimental examination confirm that both the deformation and microstructure are non-uniformly distributed in the as-forged gears. Decreasing deformation temperature or increasing strain rate is beneficial to obtaining fine-grained microstructure but is harmful to the uniformity in deformation or microstructure. The level of the non-uniformity results from the complex shape of gear and the friction between the billet and dies, which is closely associated with the characteristics of flow stress curve. 相似文献
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针对工业机器人用SCM420钢制行星齿轮热处理畸变问题,采用改进的正火工艺以调整渗碳前的预备组织,并设计合理的装料方案和冷却方式等措施,同时在渗碳过程中采用阶梯升温的工艺,有效地控制了渗碳淬火过程中齿轮畸变。结果表明,采用优化正火后可得到均匀一致的铁素体+珠光体的组织,硬度为175 ~180 HBW。随后经渗碳淬火回火后,批量生产的行星齿轮表面硬度、心部硬度和有效硬化层深度均值分别为59.74 HRC、40.44 HRC和0.530 mm。渗碳层中的马氏体级别为1级,残留奥氏体和碳化物级别为1~2级;心部组织级别为1~2级。齿轮精度、平面翘曲、齿沟振幅和齿形齿筋等全部满足技术要求。 相似文献
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为探究合金元素变化对渗碳淬火齿轮性能的影响规律,以20MnCr5低碳合金钢制齿轮为研究对象,利用JMatPro软件计算得到两种含不同合金元素的20MnCr5钢的材料性能参数;基于有限元方法开展齿轮渗碳淬火模拟分析,根据实际热处理工艺路线,建立渗碳淬火过程的数学模型,通过COSMAP软件模拟了齿轮的渗碳淬火热处理工艺过程,对比分析合金元素变化对渗碳淬火20MnCr5钢齿轮的温度场、组织场和硬度场的作用结果。研究表明,模拟值与试验值具有较好的一致性。温度场和渗碳层对合金元素含量的变化反应不明显,而渗碳淬火后的组织分布和硬度分布受C、Mn、Cr、Al等合金元素变化的影响较大。 相似文献
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为了降低弧齿锥齿轮传动噪声,改善齿轮副的啮合质量,修正轮齿热处理后产生的变形以提高齿轮的工作精度,硬齿面弧齿锥齿轮精加工技术是一广受行业关注的研究对象。根据弧齿锥齿轮切削加工近年来的研究成果,分析了硬齿面弧齿锥齿轮精加工方面已经取得的进展,对弧齿锥齿轮硬齿面精加工方法进行了综述,对我国弧齿锥齿轮硬齿面刮削加工中应注意的问题进行了阐述,结合运用刮削技术进行硬齿面加工的实例,对弧齿锥齿轮硬齿面刮削过程中加工工艺的制定、刮削余量的控制、机床的选定、基准的加工等方面进行了详细分析,并对今后刮削技术在刀具材料的优化、刀盘造型的设计、数控机床的应用等方面的研究进行了展望,展现了硬齿面刮削加工技术在弧齿锥齿轮精加工中应用的广阔前景,以便为后来的齿轮工作者进行弧齿锥齿轮硬齿面刮削技术的研究提供思路。 相似文献