共查询到18条相似文献,搜索用时 171 毫秒
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分析了传统重载齿轮深层渗碳深度的确定方法,列出了近年部分重载齿轮对渗碳层深度要求的变化。选用不同直径的代表性试样和齿形试样,进行了碳势梯度、显微硬度以及渗碳淬硬层应力测定,探索深层渗碳工艺精益化。适当降低渗碳层深度,在确保齿轮承载能力的前提下,使深层渗碳过程成为节能减排、清洁高效的加工技术。 相似文献
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李迎春 《热处理技术与装备》1994,(3)
渗碳是制造承受重载的机器零件,如齿轮、轴和轴承的一种非常有效的工艺。就弯曲和接触疲劳而言,渗碳钢的抗弯曲、抗接触疲劳性能优于完全硬化钢和用其它表面硬化处理方法处理的钢。 相似文献
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阐述了大型重载齿轮深层渗碳工艺控制的要点,其中包括渗碳温度和时间的合理选择,强渗与扩散时间的最佳分配,碳势控制的途径和要求,初步探讨了渗碳变形规律及控制方法。 相似文献
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基于机车用重载齿轮的热处理工艺要求,对18CrNiMo7-6钢进行920~1050 ℃的伪渗碳工艺处理,横向对比研究了试验钢经常规渗碳以及不同温度高温渗碳处理后的组织及力学性能;结合Aichelin计算机辅助模拟设计软件工艺模拟结果,制定高温渗碳工艺流程,对18CrNiMo7-6钢制齿轮进行高温渗碳处理,并与常规渗碳齿轮进行了组织及性能的对比研究。结果表明,与热处理前相比,经不同温度和时间的伪渗碳处理后,18CrNiMo7-6钢的综合力学性能均有所下降,但通过控制渗碳后的冷却过程,可以显著提高其最终热处理后综合力学性能;增加渗碳温度和碳势,可以大幅提高渗碳效率;对18CrNiMo7-6钢制齿轮进行最高温度1050 ℃高温渗碳,渗碳效率提高约65%,经高温渗碳后,齿轮组织、综合力学性能以及单齿弯曲疲劳强度相比于常规渗碳齿轮均未降低。 相似文献
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有关稀土催渗渗碳问题的探讨 总被引:1,自引:0,他引:1
邢大志 《热处理技术与装备》2006,27(2):25-28
通过分析浅层渗碳与深层渗碳的不同特点,就稀土催渗在深层渗碳中出现的黑色异常组织和碳化物过深现象以及大型重载齿轮深层渗碳时,使用稀土催渗剂需要注意的问题和工艺控制方法.提出了控制碳化物深度的设想,建立了形成碳化物的最大深度与有效硬化层深度比例的数学表达式,以达到提高大型重载齿轮热处理质量的目的. 相似文献
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The fatigue performance of gas carburized SAE 8620 steel was evaluated as a function of case depth. To vary the case depths, different carburizing times were applied. The typical times were: 45 min, 3 and 5 h at the temperature of 940 °C. To cause failure in the rotating bending fatigue specimens, the applied load was chosen as the equivalent load at 106 cycles for the material when is subjected to bending fatigue. The characterization of the specimens was carried out using X-ray diffraction technique for stress measurement and retained austenite and optical metallographic examination. The fractured surfaces were cleaned in an ultrasonic bath and examined using scanning electron microscope (SEM) equipped with EDX to evaluate the crack initiation and growth characteristics of the materials in the core and carburized case regions of specimens. The results showed that the fatigue limit was associated with the microstructure, the case depth, the distribution of retained austenite, the depth of the internal oxidation and the compressive residual stresses near the surface. The bending fatigue strength of gas carburized specimens was showed to decrease with the increasing case depths caused by the increasing of internal oxidation and nonmartensitic transformation present at the surface. 相似文献
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Case carburizing steels, such as SAE8620, are generally employed in manufacture of automotive components viz. gears and shafts. These components are often subjected to a combination of wear and fatigue loads. Though a number of coatings are available that can enhance performance under such loadings, but high processing temperatures forbid their application to heat-treated components. On the other hand, the low processing temperature for the WC/C coating permits its application to heat-treated parts. The coating exhibits favourable tribological properties, but its influence on fatigue behaviour is yet unexplored. The present work is aimed at investigating the influence of WC/C coating on the fatigue behaviour of case carburized SAE8620 steel, wherein performance of uncoated and coated specimens is compared by subjecting them to four point rotating bending fatigue tests. The results point out that the coating leads to 7% gain in endurance limit without considerably affecting the hardness and tensile strength. 相似文献
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You-Li Zhu Kan Wang Li Li Yuan-Lin Huang 《Journal of Materials Engineering and Performance》2009,18(8):1036-1040
An ultrasound-aided deep rolling process (UADR) for anti-fatigue applications was developed and used for surface enhancement
of titanium alloy specimens. The rotating bending fatigue test was performed for the UADR-treated and untreated fatigue specimens.
Fractography of the fatigue-fractured specimens was investigated via scanning electronic microscopy (SEM). Surface and subsurface
residual stress distributions after UADR treatment were measured by X-ray diffraction method. Surface morphology and roughness
were observed and measured via SEM micrograph and a Talysurf roughness tester, respectively. The results showed that a deep
layer of residual compressive stress developed and surface roughness was reduced after UADR treatment. Fatigue strength of
the titanium alloy specimens was substantially improved. The fractographic examination of the fatigue-fractured specimens
showed that the UADR-treated specimens developed finer fatigue striations than the untreated specimen. 相似文献
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目的探究固定载荷下三维表面粗糙度S_a对18CrNiMo7-6钢旋转弯曲疲劳寿命的影响。方法通过砂纸研磨制备不同表面粗糙度及纹理方向的18CrNiMo7-6钢旋转弯曲疲劳试样,测量所有试样的表面粗糙度参数S_a及三维表面形貌参数S_q、S_z、S_(sk)、S_(ku)。对试样进行旋转弯曲疲劳试验,分析疲劳寿命。结果在相同或相近粗糙度的情况下,轴向纹理疲劳试样疲劳寿命大于周向纹理疲劳试样疲劳寿命。相同纹理方向的情况下,表面三维粗糙度S_a越低,试样疲劳寿命越高。试样疲劳寿命次数与表面粗糙度参数S_a及三维表面形貌参数S_q、S_z、S_(sk)、S_(ku)均有明显的相关性。结论对于18CrNiMo7-6钢旋转弯曲疲劳试样,拥有平行于疲劳应力的机械加工纹理比垂直于疲劳应力的机械加工纹理具有更小的危害性。降低18CrNiMo7-6试样表面粗糙度,能够有效提高试样旋转弯曲疲劳寿命。纹理方向平行于疲劳应力方向的试样,表面偏斜度S_(sk)对零件疲劳寿命影响不明显。 相似文献
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磨料水射流喷丸对渗碳GDL-1钢表面完整性及疲劳性能的影响 总被引:1,自引:1,他引:1
为研究后混合磨料水射流喷丸对渗碳后GDL-1钢表面完整性及疲劳性能的影响规律,利用X射线应力衍射仪、粗糙度仪、显微硬度仪、金相显微镜、扫描电镜、透射电镜等分析了水射流喷丸强化对试样表面残余应力场、粗糙度、硬度、形貌、组织的变化规律,并用升降法测定了抛光及抛光+水喷丸两种状态下渗碳GDL-1钢拉压疲劳性能。结果表明:试样经水喷丸处理后,表面粗糙度有所增加,并且有磨料撞击形成的小凹坑及在表面残留有玻璃磨料,但同时表层脱碳层大部分被去除,硬度得到显著提升、残留奥氏体含量降低,晶粒得到细化,并且在表面形成一定深度的残余压应力层。经水喷丸处理的试样,其较未经水喷丸的疲劳极限提高了19%,且疲劳源全部在远离表面接近1/2R位置形成,这说明水射流喷丸在表层产生的高残余压应力和晶粒细化可以显著提高渗碳钢的疲劳性能。 相似文献
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Corrosion fatigue strength of copper and copper alloys, especially of multi-component aluminium bronzes The bending fatigue strength of multicomponent copper-aluminum alloys subjected to different beat treatments has been investigated by means of smooth and notched specimens exposed to air, distilled water or synthetic sea water. The corrosion fatigue strength is lowest in synthetic sea water. The influence of the structure is but small. Distilled water has less effect on the corrosion fatigue strenght. In the case of the tests in air, a correlation between fatigue strenght and strucure was found. With bending fatigue strenght tests in air, notched specimens mit certain from quotients yield, in some cases, higher values than smooth specimens. This abnormal influence of the notch disappear with additional corrosion. 相似文献