激光淬火CrMoCu合金铸铁组织及摩擦学性能研究

研究CrMoCu合金铸铁经激光淬火后淬硬层的微观组织结构特征,以及其显微硬度和减摩耐磨性能的变化。结果表明,CrMoCu合金铸铁激光淬火淬硬层依其组织特征可分为完全淬硬区和过渡区。硬化层深度为0.45～0.6mm,表面显微硬度较未淬火基体提高约140%;CrMoCu合金铸铁经激光相变硬化处理后,在不同载荷和低速下均具有较好的减摩性能;在试验范围内,CrMoCu合金铸铁经激光淬火后耐磨性能有显著提高。     

高功率激光淬火对35CrMo钢表层组织与耐磨性能的影响

采用高功率激光器对调质态35CrMo钢进行表面淬火处理,研究了不同激光功率(1.6,2.4,3.2,4.0 kW)下表层的显微组织、硬度及耐磨性能。结果表明：当激光功率为1.6,2.4 kW时,35CrMo钢表层组织中存在未溶铁素体,硬度比基体低,与GCr15钢对磨后的磨损质量变化率与基体几乎相同,耐磨性较差;当激光功率为3.2,4.0 kW时,表层组织全部为回火马氏体,平均硬度可以达到640 HV,比常规水冷淬火后的硬度提高约20%;当激光功率为32 kW时,磨损质量变化率最小,表面未发现明显的磨损痕迹,与基体相比耐磨性得到显著提高,而当激光功率提高到4.0 kW时较高的马氏体自回火程度导致硬度与耐磨性比激光功率为3.2 kW时略有降低。     

高频微锻造对45钢激光淬火层表面性能的影响

本文利用超声频微锻造机构对45钢激光淬火层表面进行了微锻造处理。利用OM、SEM观察了微锻造对45钢激光淬火层表面组织的影响;利用显微硬度计与洛氏硬度计研究了微锻造后45钢激光淬火层表面显微硬度,硬化深度方向的显微硬度。结果表明:高频微锻造处理后,45钢激光淬火形成的明显而规则马氏体组织被锻碎,表面晶粒明显细化。表面显微硬度提高了11.4%,激光淬火强化区深度方向的显微硬度影响深度为0.2 mm,其中0.1 mm处硬度提高了10.0%,0.2 mm处提高了4.5%。     

不同热处理制度对2A16铝合金显微组织和性能的影响

本文研究了2A16铝合金固溶处理后单级时效热处理工艺,分析了不同单级时效热处理工艺对2A16铝合金显微组织和硬度的影响。结果表明,在经过525℃×10min固溶后,150℃±5℃×6h单级时效时能获得较好的综合性能,为2A16铝合金时效热处理工艺参数的确定及优化提供参考依据。     

激光-TIG复合填丝焊接工艺对6061铝合金焊缝组织与硬度的影响

采用激光-TIG复合热源填丝焊接5 mm厚T651态6061铝合金,研究电弧电流对复合填丝焊接焊缝成形的影响,分析了优化工艺参数下的焊缝显微组织及显微硬度特征,并与单独TIG填丝焊接进行综合对比。结果表明：采用激光-TIG复合热源填丝焊接T651态6061铝合金,能够有效改善焊缝成形,当TIG电弧电流为140 A时焊接过程稳定,焊缝成形效果良好;复合填丝焊接焊缝中心区域的显微组织为等轴晶,熔合区组织由大量枝状晶组成;复合填丝焊接显微硬度高于单独TIG填丝焊接,焊缝区均存在软化现象,在选择的测试点范围内,复合填丝焊接焊缝中心区域的平均硬度为66.91 HV,约为母材硬度的62.0%,比单独TIG填丝焊接提高约13.1%。     

65Mn弹簧钢表面激光淬火的显微组织及性能研究

采用较大光斑的激光束对65Mn弹簧钢表面进行淬火。通过金相显微镜、显微硬度计等实验仪器研究65Mn弹簧钢在经过激光淬火后显微组织和显微硬度的变化。实验结果表明:经过激光淬火之后,65Mn弹簧钢表面出现一层显微硬化层,其显微组织主要有大量细小的针状马氏体和弥散的碳化物;硬化层深度约为300μm,硬化层硬度为772.5～978.5HV0.2,约为基体的4.2～5.4倍。     

2A12厚板铝合金淬火过程有限元建模研究

淬火残余应力可能造成工件淬后裂纹、削弱其疲劳强度以及造成其体积和形状的变化.在需要进行淬火处理的厚板结构铝合金零件中,这一情况尤为显著.因此,对厚板铝合金淬火过程进行有限元模拟,预测其淬后残余应力大小及分布,具有十分重要的意义.本文运用ABAQUS/Standard软件建立了2A12厚板铝合金的淬火过程有限元模型,并用反传热算法确定了以聚乙撑二醇(PAG)溶液作为淬火介质时的换热边界条件.为了验证模拟结果的可靠性,应用X射线法对厚板淬火残余应力进行了测量.模拟结果与实测数据具有较好的一致性,表明本文建立的有限元模型具有较高的精度.     

强激光超高硬度淬火

激光淬火可以获得超高硬度,其硬度值比常规热处理淬火高出20％以上,具有普遍规律。本文采用现代测试技术,研究了不锈耐酸钢4Cr 13激光淬火工艺参数、机械性能和微观结构之间的内在规律。研究结呆表明,激光淬火获得超高硬度是由于晶粒尺寸超细化,碳化物弥散度增加,位错密度增加以及成分起伏、组织形态变异。     

42CrMo钢磨削淬火强化层的显微组织和磨损性能

对42CrMo钢进行磨削淬火试验,研究了磨削淬火强化层的显微组织和耐磨性能。结果表明:42CrMo钢磨削淬火强化层的显微组织以片条状马氏体为主,强化层的显微硬度达到了700HV以上;磨削淬火强化层的磨损性能较基体的有明显提高。     

固溶处理对2Al6铝合金显微组织和性能的影响

研究了2Al6铝合金的固溶热处理工艺,分析了不同固溶热处理工艺对2A16铝合金显微组织和硬度的影响;结果表明,在经过525℃×10min固溶后,2A16铝合金能获得较好的固溶处理效果,为2A16铝合金后续热处理工艺参数的确定及优化提供了参考依据。     

高功率TEA CO2激光器的双波长免调切换结构

为在一台激光器上切换输出10.6/9.3μm两种波长高能激光,采用输出镜镀膜选支方法获得了9.3μm单谱线输出,其脉冲能量与原10.6μm波长基本相当.设计出双波长密闭免调切换输出结构,利用有限元分析软件MSC.Patran/Nastran对该结构的切换移动平台组件进行了静力学、热应力及热力耦合分析,并基于Matlab...     

渗碳后淬火工艺对G20Cr2Ni4A钢轴承套圈组织和性能的影响

采用德国莱卡PZ-20B型金相显微镜、200HVS-5型维氏硬度计及200HRS-150型洛氏硬度计,对渗碳G20Cr2Ni4A钢轴承套圈三种不同淬火工艺后的组织和性能进行了分析研究,确定出精准渗碳热处理工艺,使其组织及性能指标达到国外客户的要求,实现了风电增速箱轴承国产化。研究结果表明,常规油浴二次淬火工艺和常规二次盐浴等温淬火工艺虽然在材料表层组织、心部组织、晶粒度及心部硬度等方面可以满足要求,但在表面硬度及硬度梯度等方面均不能满足技术要求;低温快冷二次盐浴等温淬火工艺在所有指标上均可以很好地满足套圈技术要求。     

A study on laser assisted machining of Ti10V2Fe3Al alloy with varying laser power

Laser-assisted machining (LAM) is a promising technique to improve the machinability of various difficult-to-machine materials such as steels, nickel and titanium alloys and metal-matrix composites. Most of the research studies are focused on analyzing the effect of various cutting parameters such as cutting speeds, feed rates and depth of cut at a constant laser power despite being reported that the maximum benefit of the LAM technique can be realised when all parameters including laser power are optimised. Therefore, the primary objective of this paper is to assess the effect of laser power on the cutting temperature and cutting forces including force fluctuations during the machining of Ti10V2Fe3Al alloy. A cutting force reduction of at least 10 % was found using the assistance of a 1,600 W laser beam between cutting speeds of 55–140 m/min. Nevertheless, it was concluded that a power of 800–1200 W for the laser beam is best suited during LAM of Ti10V2Fe3Al alloy within a cutting speed range of 55–100 m/min. Further, higher cutting speeds were recommended when employing a higher power laser beam to avoid problems such as chatter and chip pile-up.     

A TEA CO2 laser with a peak radiation power of 100 MW

A high-power pulse-periodic TEA CO₂ laser is used as a component of a long-range mobile differential absorption lidar. In order to reach the ultimate peak generation power, a system for laser excitation with a supply voltage of ±40 kV and efficient preionization was developed, allowing the laser to operate at high pressures of gas mixtures of various compositions. Energy, time, and spatial characteristics of laser radiation were studied. Laser pulses with an energy of >10 J and FWHM duration of ≈30 ns were obtained. The ultimate peak laser radiation power is 100 MW, and the maximum efficiency with respect to the discharge-consumed energy is 12.6%.     

Stimulated emission on microscopic scale: Light quenching of Pyridine 2 using a Ti:sapphire laser

We report the realization of stimulated emission on a microscopic scale. An experiment is presented describing significant depopulation of the excited state of the fluorophore Pyridine 2 with a mode-locked Ti: Sapphire laser. Stimulated emission is performed at 750 nm and excitation at the frequency doubled wavelength of 375 nm. The pulses are synchronized so that the stimulating pulse follows the excitation pulse after 5 ps. The set-up is a modified 4Pi-confocal microscope employing one of the objective lenses for excitation and the opposing one for stimulated emission.     

Effect of high power diode laser surface melting on wear resistance of magnesium alloys

In the present work, an attempt has been made to improve the surface hardness and wear properties of magnesium alloys AZ31 and AZ61 through solid solution hardening and refinement of microstructures using a 1.5 kW high power diode laser (HPDL) as a heat generating source. One millimetre thick uniform overlapping melt tracks were produced on Mg alloy samples. Laser-melted samples were subjected to a two-body abrasive wear test using a modified pin-on-disc set up. The hardness and wear resistance of laser-melted samples were found far better than the as-received Mg alloy substrates. Scanning electron microscopy was used to examine microstructure of the laser-melted layers and the worn surface morphology. Fine microstructures were observed with an average grain size of less than 5 μm.     

Effect of laser power and specimen temperature on atom probe analyses of magnesium alloys

The influence of laser power, wave length, and specimen temperature on laser assisted atom probe analyses for Mg alloys was investigated. Higher laser power and lower specimen temperature led to improved mass and spatial resolutions. Background noise and mass resolutions were degraded with lower laser power and higher specimen temperature. By adjusting the conditions for laser assisted atom probe analyses, atom probe results with atomic layer resolutions were obtained from all the Mg alloys so far investigated. Laser assisted atom probe investigations revealed detailed chemical information on Guinier-Preston zones in Mg alloys.     

CO2激光熔拉锥过程光功率控制研究

基于CO₂熔拉锥技术,对熔拉锥设备的控制方法进行了改进。利用柱体Mie散射公式计算光纤在加工过程中的光能利用率,结合Grellier的热传导模型,确定了加工过程中激光功率增长与光纤拉伸距离之间的对应关系。利用计算结果,采用分段直线递增的方法对激光功率进行控制,简化了仪器控制的难度。实验得到锥腰直径2~3 μm左右的熔锥光纤,锥腰和过渡区的形状和尺寸都得到了很好的控制。     

Effect of phase composition of nanostructured refractory modifier on structure and tribological behavior of AK12M2MgN alloy

The structure and tribological behavior of the AK12M2MgN alloy reinforced by nanostructured fillers based on BN and SiO₂ micropowders are studied. It is shown that the modification of the micropowders by reactive elements is accompanied by the synthesis of nanosized ceramic compounds on their particles. This structure of the fillers leads to the dispersion of the structural components of the alloy, a considerable increase in its wear resistance, and a decrease in the coefficient of friction.