共查询到19条相似文献,搜索用时 62 毫秒
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根据车轮喷水淬火时温度发布的研究结果,按小样品的尺寸和介质的冷却特性制定了实验室试验方案,较好地模拟了车轮踏面近表层的冷却条件,制作 的残余应力标块完全符合要求。该试验方法也可用于车轮轮箍的其它研究工作。 相似文献
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采用有限元数值模拟研究7050铝合金H型截面构件淬火过程残余应力大小、分布及规律。研究结果表明:构件截面淬火后残余应力的分布情况为:表层受拉应力,芯部受压应力。构件截面在X方向上的淬火残余应力主要集中在过渡圆角区域、筋顶以及腹板区域。其中构件截面过渡圆角区表面出现最大压应力,为-114MPa;过渡圆角芯部区域出现最大拉应力,为68 MPa。构件截面在Y方向上的淬火残余应力主要出现在过渡圆角区表面、筋外壁及筋芯部位置。其中最大压应力和最大拉应力也分别出现在过渡圆角区表面及芯部,分别为-114 MPa和79 MPa。 相似文献
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超声波是测量车轮轮辋残余应力的有效方法,R71、R8T车轮的化学成分影响可以通过热处理工艺来弥补,根据车轮轮辋材料的屈服强度改变回火工艺可以降低残余应力水平。 相似文献
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研究了淬火/回火热处理中淬火温度和回火时间对Ti48Al2Cr0.5Mo合金晶粒细化的影响。研究结果表明:一定的淬火/回火热处理能将粒径约为1 000 μm的铸态组织细化成为18~30 μm的均匀双态组织。TiAl基合金的细化效果与淬火阶段的加热温度密切相关,温度升高,得到的块状组织较细,羽毛状组织体积分数减少。在两相区回火时,高温淬火组织的回火组织较细,而随时间的延长晶粒长大,但不明显。此外,从理论上探讨了淬火/回火工艺细化TiAl基合金显微组织的机理。 相似文献
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By combining thermomechanical coupling finite element analysis with the characteristics of phase transformation [continuous cooling transformation (CCT) curve], the thermal fatigue behavior of train wheel steel under high speed and heavy load conditions was analyzed. The influence of different materials on the formation of the phase transformation zone of the wheel tread was discussed. The result showed that the peak temperature of wheel/track friction zone could be higher than the austenitizing temperature for braking. The depth of the austenitized region could reach a point of 0.9 mm beneath the wheel tread surface. The supercooled austenite is transformed to a hard and brittle martensite layer during the following rapid cooling process, which may lead to cracking and then spalling on the wheel tread surface. The decrease in carbon contents of the train wheel steel helps inhibit the formation of martensite by increasing the austenitizing temperature of the train wheel steel. When the carbon contents decrease from 0.7% to 0.4%, the Ac3 of the wheel steel is increased by 45 ℃, and the thickness of the martensite layer is de creased by 30 %, which is helpful in reducing the thermal cycling fatigue of the train wheel tread such as spalling. 相似文献
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车轮钢摩擦热影响区的相变及其损伤机理 总被引:2,自引:0,他引:2
将有限元热力耦合一温度场分析与材料相变特征的实验研究相结合,研究了高速度(200kin/h)、大载荷(10^5N)条件下车轮摩擦热影响区的相变过程,探讨了材料对该过程的影响。结果表明,轮一轨摩擦导致的车轮踏面局部升温可超过材料的奥氏体相变的临界点,碳含量为0.5%时,完全奥氏体化层的深度可达0.6mm;过冷奥氏体高速冷却,几乎全部形成脆硬的马氏体薄层,造成踏面剥离。通过降碳来降低车轮钢奥氏体相变的临界点,可以显著抑制踏面马氏体层的形成。随着碳含量从0.7%降至0.4%,材料的Ae3提高45℃,马氏体层的厚度减小30%,有助于减少车轮踏面的热疲劳损伤。 相似文献
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Computer software is developed for predicting the basic thermal characteristics in the plasma treatment of wheel rims for locomotives: the temperature, cooling rates, heat-flux density, and thickness of the martensitic layer at the wheel’s working surface. To verify the validity of this software, the results obtained are compared with thermometer readings and metallurgical data for the thickness of the martensitic layer. Two new features of the thermophysical model are the specification of the heat-transfer parameters in the plasma flare so as to ensure strengthening of the metal at the wheel rim by micromelting; and the ability to use the predicted temperatures and cooling rates in precision estimates of the martensitic-layer thickness. Estimates of the short-term thermal stress at the rim’s working surface show that compressive stress predominates. That is consistent with experimental data regarding the residual stress in steel samples after plasma treatment. If the proposed computer model is used in determining optimal conditions for the plasma quenching of locomotive wheels, the expenditures of time and material resources will be less than in in purely empirical selection of the operating conditions. 相似文献
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李斌 《金属材料与冶金工程》2004,32(6):14-17
研究了淬火温度、冷却方式、回火温度和回火次数对高碳高钒高速钢轧辊组织和性能的影响.确定了最佳热处理工艺参数。结果表明。盐冷高速钢轧辊具有优良的淬透性。不易出现裂纹.辊面硬度高而且均匀,耐磨性好.和高铬铸铁轧辊相比,高速钢轧辊寿命提高8.4倍。 相似文献
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为研究微晶刚玉砂轮成型磨削20CrMnTi齿轮的表面完整性,开展了20CrMnTi齿轮成型磨削试验,分析了砂轮线速度、轴向进给速度及径向进给量对齿面粗糙度、表层/次表层显微硬度、微观组织和残余应力的影响规律,探讨了由磨削引起的磨削烧伤、微观裂纹等损伤缺陷的形成机理,结果表明:径向进给量对表面粗糙度的影响最显著,砂轮线速度次之,轴向进给速度最不显著;磨削温度过高会导致磨削烧伤,淬火烧伤使得表面硬度提高5%~20%,回火烧伤则导致表面硬度不同程度地下降;表层组织从外至内分别为白层、暗层和基体组织,白层主要由致密的马氏体+碳化物+残余奥氏体组成;砂轮线速度和径向进给量的增大使得由磨削引起的残余拉应力增大,表面残余压应力下降并逐渐向拉应力转变,当表面最终残余拉应力大于材料的断裂强度时,表面产生微观裂纹. 相似文献
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M. A. Filippov M. A. Gervas’ev Yu. V. Khudorozhkova V. V. Legchilo 《Steel in Translation》2013,43(11):720-723
The influence of the quenching temperature on the quantity of residual austenite, its stability, and its ease of deformational martensitic transformation in 150XHM steel is studied. In the addition, the hardening and abrasive-wear resistance of the steel are studied as a function of the quenching temperature. The dependences of the steel’s hardening and wear resistance on the quenching temperature are of opposite form. The drop in hardness with increase in quenching temperature is due to increase in the content of residual austenite. At the same time, the relative ease of deformational martensitic transformation in the metastable residual austenite results in increase in wear resistance and microhardness of the worn surface. 相似文献