共查询到20条相似文献,搜索用时 968 毫秒
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针对大型船舶发动机链条内外链板之间磨损严重的问题,提出采用激光淬火表面改性技术来提高链板表面力学性能的方法,并对45Mn钢表面进行单道和多道激光淬火试验,分析了其激光淬火后的显微组织和硬度变化规律。结果表明,单道激光淬火后形成了以板条马氏体与细小马氏体为主的相变硬化区。当激光功率为300~900 W、扫描速度为5~20 mm/s时,45Mn钢单道激光淬火后的表面硬度为850~950 HV,有效硬化深度约为0.63 mm,在基本没有改变表面粗糙度的前提下降低磨损体积,为未激光淬火时的45.1%~53.0%。多道搭接激光淬火形成以回火马氏体为主的软化区。经搭接率为30%的多道激光淬火后45Mn钢表面硬度较为平均,回火软化区的宽度为0.68 mm。 相似文献
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金属材料的激光相变硬化机理及其工艺参数优化 总被引:2,自引:3,他引:2
简要介绍了激光表面技术中的激光相变硬化,阐述了金属材料的激光相变硬化机理,分析了激光功率、扫描速度和光斑直径等工艺参数对硬化效果的影响,指出用激光能量密度描述激光加工工艺参数之间的耦合作用对硬化效果的影响规律。 相似文献
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根据激光相变硬化理论计算模型,编制了模拟激光束扫描作用下沿工件纵向硬化层分布的有限元计算程序。该程序可用来自动确定激光变速扫描中的变速段长度。结合分段变速扫描工艺及参数优化设计,可以实现纵向硬化层分布均匀性控制。其有效性从模拟和试验两方面得到了验证。 相似文献
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Laser transformation hardening (LTH) of unalloyed titanium of 1.6 mm-thick sheet, nearer to ASTM Grade 3 of chemical composition was investigated using 2 kW CW Nd:YAG laser. The effects of laser power (750-1 250 W), scanning speed (1 000- 3 000 mm/min) and focal point position (from -10 to -30 mm) on the heat input, and hardened-bead geometry (i.e. hardened bead width (HBW), hardened depth (HD) and angle of entry of hardened bead profile with the surface (AEHB)) were investigated using response surface methodology (RSM). The experimental plan is based on Box-Behnken design matrix method. Linear and quadratic polynomial equations for predicting the heat input and the hardened bead geometry were developed. The results indicate that the proposed models predict the responses adequately within the limits of hardening parameters being used. It is suggested that regression equations can be used to find optimum hardening conditions for desired criteria. 相似文献
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S. Sathik Basha V. M. Periasamy M. Kamaraj S. M. Shariff 《Journal of Materials Engineering and Performance》2013,22(12):3689-3698
Laser surface alloying (LSA), with Wallex-50 and Tribaloy-700 powders, and laser transformation hardening (LTH) reduced the silt erosion rate in 16Cr-5Ni steel. Slurry erosion wear tests were conducted on 16Cr-5Ni steel, LSA-modified steel, and LT-hardened steel at different angles of impingement and velocities at a constant size of silica particles. The LSA-modified steel and LT-hardened steel showed improved wear resistance by about 1.5-3 times as compared to substrate 16Cr-5Ni steel for all angles of impingement. This improvement in hardness and erosion resistance was due to the incorporation of carbides and hard complex phases after LSA and LTH. 相似文献
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Laser surface hardening of gray cast iron used for piston ring 总被引:2,自引:0,他引:2
Jong-Hyun Hwang Dae-Young Kim Joong-Geun Youn Yun-Sig Lee 《Journal of Materials Engineering and Performance》2002,11(3):294-300
The process parameters for laser surface-hardening has been experimentally established for improving the wear life of piston
rings used for marine diesel engines by the formation of a proper hardened layer on it. The parameters of interest were the
laser power and travel speed. Various hardened layers of gray cast iron were analyzed with respect to microstructure, hardness
value, hardening depth, surface roughness, and wear resistance. The hardness of the laser-hardened layer was in a range between
840 and 950 Hv0.1, regardless of the laser power and travel speed range studied. Both the surface roughness and hardening
depth increased in an almost linear manner with the increase in the heat input applied. Thus, the hardened layers formed with
heat input ranges between 30 and 45 J/mm satisfied the piston ring application requirements for surface roughness (<6.3 μm
in Ra) and the minimum effective hardening depth of 0.3 mm (>450 in Vickers number). Wear-test results obtained using a pin-on-disk-type
wear-test machine showed that the wear life of the laser-hardened layer was almost twice that of the untreated one. This was
directly attributed to the formation of the martensitic microstructure. 相似文献
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采用TH-3DC3000型激光加工系统对铬钼铸铁进行了激光表面淬火处理,研究了不同激光功率和扫描速度对铬钼铸铁显微组织、表面硬度及硬化层深度的影响。结果表明,经激光表面淬火后,铬钼铸铁的组织由硬化区、过渡区和基体3个区域组成,硬化区组织为隐晶马氏体、残留奥氏体和球状石墨,过渡区组织为隐晶马氏体、珠光体和球状石墨,基体组织为铁素体、珠光体和球状石墨。在激光表面淬火未对试件产生过热影响时,激光功率的增大和扫描速度的降低均会提升铬钼铸铁的表面硬度和硬化层深度。在5 mm×20 mm的矩形激光光斑下,确定最优的参数组合为激光功率2300 W、扫描速度0.003 m/s,采用该参数组合对铬钼铸铁进行激光淬火处理时,表面硬度为760 HV0.3,硬化层平均硬度为724 HV0.3,硬化层深度可达1.4 mm以上。 相似文献
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Ruifeng Li Yajuan Jin Zhuguo Li Kai Qi 《Journal of Materials Engineering and Performance》2014,23(9):3085-3091
The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening. 相似文献
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45钢电子束相变硬化温度场数值模拟与实验验证 总被引:1,自引:0,他引:1
建立了移动电子束高斯热源作用下的三维相变硬化过程中温度场的数学模型,分析过程中考虑了热源分布、热物性参数、热辐射等因素对温度场的影响,得到了电子束扫描相变硬化温度场的分布规律和硬化层的形态,并进行了实验验证;探讨了电子束工艺参数对硬化区深度和宽度的影响。结果表明:移动电子束高斯热源作用下的温度分布等值线呈勺状,表面最高温度滞后于束流中心,且处理后硬化层横截面呈月牙状;在固态相变条件下,硬化层的宽度和深度随着扫描功率的增加呈非线性增加,随着扫描速度的增加呈非线性减小。 相似文献
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This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P; laser beam diameter, Db; and the heat intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving heat source method) by considering the laser beam as a moving plane (disc) heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a heat source with a pseudo-Gaussian (or normal) distribution of heat intensity. The analytical results were compared with the experimental results published in the literature. In laser heat treatment of steel, it is generally considered preferable to use a wider heat intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P, laser beam diameters, Db, and various heat intensity distributions. Since diffusion during the heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper. 相似文献
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利用半导体激光宽带对12CrNi3外锁止套局部进行表面淬火处理,并对处理后的零件进行外观检验、显微组织观察、硬度检测分析和摩擦磨损试验。试验结果表明:采取定光斑方式,激光头到工件表面扫描区域中心点距离375 mm(离焦量为0),工件倾斜22°,激光头倾斜18°,温度1350 ℃,扫描速度9 mm/s,单道扫描后表面平整性最好。表面激光淬火硬化层为750~1000 μm,最浅处为443.1 μm,硬化区组织为极细小马氏体组织,硬度达600~700 HV0.2,是基体硬度的2倍左右, 约为渗碳+淬火态硬度的1.3倍,且相变硬化区耐磨性能明显提高。 相似文献
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激光扫描速度对Co基合金堆焊重熔层组织和硬度的影响 总被引:1,自引:0,他引:1
研究了激光功率为2.5kW时,三种不同扫描速度(2mm.s-1、4mm.s-1、8mm.s-1)对重熔的Co基合金堆焊层熔宽、熔深、搭接宽度、枝晶尺寸以及显微硬度分布的影响。试验结果表明,堆焊层经激光重熔后,随着扫描速度的提高,重熔层熔宽和熔深、搭接宽度、枝晶尺寸均随之减小,组织较原始堆焊层明显细化,硬度明显提高。然而,当扫描速度为8mm.s-1时,搭接宽度为零,出现未重熔塔接部分,使得堆焊重熔层表面硬度出现较大波动。 相似文献
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