共查询到19条相似文献,搜索用时 62 毫秒
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李振 《热处理技术与装备》2023,(1):9-12
对45钢表面进行激光淬火实验,采用认识法和正交法分析电流、脉宽、频率等因素变化对相变区硬度的影响规律。通过选取最佳工艺参数,为达到最优硬化效果提供依据。 相似文献
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通过在Gleeble-1500热模拟试验机上的模拟加热和冷却实验,研究了在不同温度下珠光体等温转变后,珠光体轨钢的显微组织和力学性能。结果表明:随着等温温度的升高,相同奥氏体化温度下,相变后珠光体组织中珠光体域的尺寸也随之增大,珠光体片间距随相变温度的升高也逐渐增大。实验钢的力学性能测定结果表明,硬度随着相变温度的升高,呈直线下降趋势;室温冲击韧度随等温温度的升高,也呈下降趋势。从珠光体转变机理方面,对上述关系进行了分析,阐明了相变温度对控制珠光体钢轨组织和性能的影响。 相似文献
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Stephen Skvarenina 《Surface & coatings technology》2006,201(6):2256-2269
This paper presents predictive modeling and experimental results on laser hardening of AISI 1536 steel shafts with a complex geometric feature. A three-dimensional thermal model is used to predict the workpiece temperature distribution, which is coupled to a two-dimensional kinetic model to predict the resultant hardness and phase distribution. Surface temperature measurements are performed to validate the thermal model, while the kinetic model is validated through furnace hardening and laser hardening experiments. A 2.5-mm case depth is achieved on simple geometry parts, while a 1.5-mm case depth is obtained on parts with a groove of 2.0-mm radius. The case hardness values and distributions show good agreement with predicted results and are found to be uniform throughout, with the values between 55 and 57 in Rockwell C. 相似文献
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Predictive modeling and experimental results for residual stresses in laser hardening of AISI 4140 steel by a high power diode laser 总被引:1,自引:0,他引:1
Neil S. Bailey 《Surface & coatings technology》2009,203(14):2003-2012
A predictive model for residual stresses induced in a laser hardened workpiece of AISI 4140 steel with no melting has been developed and experimentally verified. A transient three-dimensional thermal and kinetic model is first solved to obtain the temperature and solid phase history of the workpiece, which is then sequentially coupled to a three-dimensional stress model to predict residual stresses. The phase transformation strains are added to the thermal strains at each time step during the heating and cooling cycles to obtain the resultant residual stresses in the workpiece. The importance of considering phase transformation has been explained through the comparison of the magnitudes of residual stresses with and without the inclusion of phase transformation kinetics. The model predicted strong compressive residual stresses of about 200 MPa in the heat affected zone due to austenite-to-martensite transformation. The predictions matched well with the X-ray diffraction measurements. 相似文献
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An experimentally based thermo-kinetic hardening model for high power direct diode laser cladding 总被引:1,自引:0,他引:1
Soundarapandian SanthanakrishnanFanrong Kong Radovan Kovacevic 《Journal of Materials Processing Technology》2011,211(7):1247-1259
High power direct diode laser (HPDDL) based cladding is found to be an economical process for repairing or building valued components and tools that are used in the automotive, aerospace, nuclear and defense industries. In this study, a 2-kW HPDDL of 808 nm in wavelength, rectangular-shaped laser spot of 12 mm × 1 mm with uniform distribution (top-hat) of laser power is used to carry out the experiments. An off-axis powder injection system is used to deposit tool steel H13 on the AISI 4140 steel substrate. A number of experiments are carried out by changing the laser power and scanning speeds while keeping a constant powder feed rate to produce different sizes of clad. An experimentally based finite element (FE) thermal model is developed to predict the cross-sectional temperature history of the cladding process. The temperature-dependent material properties and phase change kinetics are taken into account in this model. As-used experimental boundary conditions are adopted in this model. The acquired temperature history from the FE model is used to predict the temperature gradient, rates of heating and cooling cycles, and the solidification of the clad to the substrate. The FE thermal model results are coupled with thermo-kinetic (TK) equations to predict the hardness of the clad to the substrate. Metallurgical characterization and hardness measurements are performed to quantify the effect of processing parameters on the variation of clad geometry, microstructure, and the change of hardness of the clad to the substrate. The results show that a good metallurgically bonded clad of hardness uniformity is achieved. 相似文献
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Jong-Do KIM Myeong-Hoon LEE Su-Jin LEE Woon-Ju KANG 《中国有色金属学会会刊》2009,19(4):941-945
Laser transformation hardening(LTH) is one of the laser surface modification processes. The surface hardening of rod-shaped carbon steel (SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head. The LTH characteristics by dominant processes, longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined. Especially, two concepts of circumferential speed and theoretical overlap rate were applied. When laser power increased or circumferential speed decreased, the surface hardening depth gradually increases due to the increased heat input. Moreover, the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease, which results from tempering effect by overlap. Finally, the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution. 相似文献
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