ANSYS数值模拟激光熔覆Ni/SiC工艺参数优化

针对修复模具表面失效的问题,采用数值模拟技术对激光熔覆Ni/SiC过程进行参数优化。建立了以不同激光电流、扫描速度及离焦量作为优化工艺参数的有限元分析模型,进行激光熔覆仿真分析,通过改变工艺参数的大小对温度场和应力场进行研究。结果表明：温度和残余应力都随激光电流的增大而升高,且它们都随着扫描速度和离焦量的增大而减小。其中,激光电流、离焦量对温度场的影响比扫描速度明显;离焦量对应力场的影响比激光电流和扫描速度明显。经应力场实验验证,最终实验结果与应力场模拟结果的横向残余应力最高处相差76 MPa,纵向残余应力最高处相差86 MPa。实验结果与应力场模拟结果仅存在细微误差,且误差在合理范围内,证明了模拟结果的正确性。对激光熔覆工艺参数进行优化,优化后的工艺参数为：激光电流120 A,扫描速度为60 mm/min,离焦量为50 mm。     

45#钢表面NiCrBSi合金激光熔敷层的组织和硬度

为提高45^#钢表面硬度及耐磨性能，采用激光熔敷技术在其表面制备NiCrBSi合金涂层，利用X射线衍射仪、扫描电镜和透射电镜分析了熔敷层的微观组织，利用显微硬度计测试了熔敷层的硬度，结果表明，激光熔敷层的组织由γ-Ni树枝晶、γ-Ni Ni3B共晶、M7C3树枝晶和CrB颗粒组成，激光熔敷层的硬度在HV800～900之间．     

单道激光熔覆Ni基合金涂层的组织与性能研究

采用10 kW高功率连续CO2横流激光器在Cr12MoV模具钢表面单道熔覆Ni60AA合金粉末,研究不同激光工艺参数对熔覆层组织和硬度的影响,利用光学显微镜观察熔覆层显微组织,并用自动转塔显微硬度计测量熔覆层显微硬度.结果表明：激光功率的大小对热影响区附近的显微硬度影响不大,扫描速度为400 mm/min时熔覆层次表层硬度可以达到856 HV0.2.熔覆层主要相组织是富Ni的γ-Ni奥氏体枝晶和多元共晶的混合组织,Cr,B等元素的碳化物硬质相弥散分布在基体上.     

激光熔覆Ni基高温合金粉末涂层磨损机制图

目的 研究激光熔覆Ni基高温合金粉末涂层的磨损性能和磨损机理,建立涂层的磨损机制图.方法 以Ni基高温合金粉末为原料,在crM0铸铁表面利用激光熔覆技术制备了减摩耐磨的复合涂层.应用均匀设计的试验方法 进行试验方案的设计.根据不同工作参数组合下的磨损率建立其磨损机制图,根据试验结果 对熔覆层的磨损机理进行了研究.结果 建立了涂层的磨损机制图.激光熔覆Ni基高温合金粉末涂层的磨损形式主要包括严重磨损和轻微磨损.主要磨损机制包括剥层磨损、黏着磨损、磨粒磨损和氧化磨损等.结论 根据磨损机制图.可以确定涂层的安全工作区域为载荷小于4 MPa时,滑动速度大于1.5 m/s;载荷大于4 MPa时.滑动速度在1～2.0m/s.     

半导体激光熔覆高硬Ni基WC涂层

为提高球阀的使用寿命,通过激光熔覆技术,在304钢基体上制备Ni28+WC涂层,并研究WC含量和激光器功率对涂层表面性能的影响.借助金相显微镜、显微硬度计研究了不同含量WC下涂层的裂纹情况、稀释率及硬度.研究结果表明:随着WC含量升高,涂层硬度显著提高,稀释率逐渐降低,增加激光输出功率可以促进WC颗粒融化从而提高稀释率,当WC含量为30%时,涂层无裂纹,平均显微硬度达到580Hv0.1,稀释率为4.9%,涂层与基地之间实现冶金结合.WC含量高于40%时,由于未融化和析出的WC颗粒的增多,涂层开裂.     

合金结构钢30CrMo激光熔覆组织的研究

以波长为1.06μm，功率密度为10～20kw／cm^2的Nd：YAG脉冲激光器的聚焦光束为热源，对30CrMo合金结构钢的表面进行Ni基合金的熔覆处理。用扫描电镜和能谱仪观察和分析了熔覆层的显微组织及成分。结果表明，涂层致密无裂纹。在微观结构上，涂层由表及里形貌不同，存在粗大枝晶区、柱状枝晶区和基体3个不同区域，它的相组成为马氏体、奥氏体及花状WC晶体。     

激光熔覆制备TaC/FeCoCrNiTiMo熔覆层组织性能研究

采用激光熔覆技术在45#钢表面制备添加碳化钽(TaC)纳米颗粒的FeCoCrNiTiMo高熵合金熔覆层,利用X线衍射（XRD）、扫描电镜（SEM）、能谱仪（EDS）及显微硬度计分析测试熔覆层相结构、组织形貌及截面硬度. 研究表明,在FeCoCrNiTiMo高熵合金熔覆层中添加TaC纳米颗粒后,其相结构以体心立方结构的FeCrNi固溶体和面心立方结构的NiCrCoMo固溶体为主,并含有极少量的金属间化合物,熔覆层维氏硬度（HV）达到1058.89 ,是基材硬度的两倍.     

基于激光熔覆复合涂层的滑动轴承制造工艺研究

为了增强滑动轴承面硬度和耐磨性,提高滑动轴承工作性能与使用寿命,提出了一种基于TiC-TiB2增强Co基复合涂层激光熔覆增材制造技术的滑动轴承制造工艺.实验结果发现复合涂层中TiC、TiB2物质对基材的硬度和耐磨性有较明显提高.     

Ni基合金表面激光熔覆Co基合金的组织与性能

用同步送粉法，在Ni基合金表面上制取了Hoegan aes Co基合金（HMSP 2537）的激光熔覆层。利用金相显微镜，扫描电镜，X射线衍射仪，显微硬度计对熔覆层的组织，相结构，硬度进行了分析和测试。结果显示，熔覆层的不同区域组织及性能不均匀；激光输入功率增大，枝晶间距增大，硬度降低。     

扫描速度对45钢表面激光熔覆层形貌及性能的影响

利用CO2激光器及SLC-2025D数控加工机床,改变激光的扫描速度,采用同步送粉法在45钢基体上熔覆NiCrSiB合金.用体视显微镜观察熔覆层形貌,测量熔覆层的几何尺寸;用扫描电镜观察熔覆层各个区域的显微组织形貌;用显微硬度计和M273电化学测试系统测试熔覆层的显微硬度和耐蚀性能.结果表明:随着扫描速度的增加,熔覆层的熔宽与横截面面积呈下降趋势;熔覆层的树枝晶细化,平面晶宽化.随扫描速度的增加熔覆层的耐蚀性能由于晶粒的细化而趋于良好.熔覆层显微硬度是基体的3~4倍.随着扫描速度的增加,熔覆层中颗粒相和合金元素的偏析减少,使硬度有所降低.     

激光熔敷镍基自熔性合金粉末的研制

针对激光熔敷表面处理技术对合金粉末材料性能的要求，分别研究了合金粉末的B含量、Si含量以及B、Si含量配比对激光熔敷的工艺性能、粉末形貌及涂层性能的影响，研制出具有良好的工艺性能和使用性能的激光熔敷用镍基自熔性合金粉末．     

CO_2激光熔覆镍基合金粉末的组织和性能

为了提高核发电成套设备的阀体性能,采用CO_2激光器在SUS316LN奥氏体不锈钢表面熔覆了镍基合金粉末.利用光学显微镜、扫描电子显微镜、电子探针分析仪、X射线衍射仪、能谱分析仪、显微硬度计和磨损试验机等对熔覆层的组织和性能进行了研究.结果表明,从熔覆层熔合线到表面的组织依次由平面晶生长区、亚共晶区,共晶区与过共晶区组成.亚共晶组织的初晶相由γ-Ni相组成,而过共晶组织的初晶相由Cr B和Cr7C3相组成.CO_2激光熔覆层具有较高的维氏硬度和耐磨性能,且其裂纹断口形貌属于解理断裂.     

Investigation on laser cladding of MoSi2 powder on steel

The feasibility of the fabrication of coatings for elevated-temperature structural applications by laser cladding MoSi2 pow- der on steel was investigated. A dense and crack-free fine coating, well-bonded with the substrate has been obtained by this technique This coating consists of FeMoSi, Fe2Si and a small amount of MosSi3 due to dilution of the substrate in the coating. The microstructure of the coating is characterized of typical fine dendrites, The dendrites are composed of FeMoSi primary phase, and the interdendritic areas are two eutectic phases of FeMoSi and Fe2Si. The hardness of the coating reaches 845 Hv0.5, 3.7 times larger than that of the steel substrate （180 Hv05）.     

基于有限元20GrMnTi合金钢激光熔覆工艺数值模拟

以20GrMnTi合金钢为基体材料及熔覆层为Ni60材料建立有限元分析模型,模拟不同熔覆层厚度的瞬态过程分析其温度场和应力场,结果表明:激光功率一定时,熔覆层厚度的增加对结点温度的影响最大,且降低了基体与涂层两者之间的结合强度,熔覆层表面质量较差,为优化工艺参数提供依据.     

Effects of Powder Feeding Rate on Interaction between Laser Beam and Powder Streamin Laser Cladding Process

A theoretical model was presented to calculate the laser intensity distribution and the particle temperatures at different sites of the workpiece in the laser cladding process By using this model, the effects of the powder feeding rate on the laser intensity distribution and the particle temperatures were inrestigated ,the caleuluted results under the condition of different injection angles were also plotted it is shout that with increasing the injection angle,the laser inuensity distributwons are similar but the peak ralue of the laser intensity decreases simdlaneously the peak ralue of the particle tenperature increases and the disribution of the particle temperatures gets central symmetrical gradually.these tests reslts should be considered in model of laser cladding due to their sub the effects on the dynamic processes in laser molten pool.     

冷扎Q235钢/激光熔覆合金钢摩擦磨损

通过对9SiCr钢表面进行合金激光熔覆处理,在摩擦磨损实验机上对熔覆合金钢与Q235钢配副进行了摩擦磨损性能实验.通过摩擦磨损实验研究了参数如载荷、滑动距离、滑动速度、润滑条件等对Q235钢与熔覆合金钢的磨损量的影响,熔覆合金钢与Q235钢的磨损量与压力和滑动速度成正比.Ni合金钢的耐磨性比Co合金钢要好.通过扫描电镜分析了熔覆合金磨损机理,熔覆合金钢磨损主要以磨粒为主,同时表面存在大量凹坑,而Q235钢以磨粒和塑性变形为主.     

Microstructure and thermal physical parameters of Ni60-Cr3C2 composite coating by laser cladding

To satisfy performance and long life requirements for hot forging die, Ni60-Cr₃C₂ composite coatings were prepared on the high-speed steel W₆Mo₅Cr₄V₂ using laser cladding technology. Laser clad coatings with different ratios of Ni60:Cr₃C₂ were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and microhardness tester, respectively. Specific heat capacity and thermal conductivity were measured by Laser Thermal Constant Meter. Thermal expansion coefficient and elastic modulus were measured by Dynamic Mechanical Thermal Analyzer and Electro-Hydraulic Servocontrolled Testing System, respectively. The results indicated that Ni60+50wt% Cr₃C₂ composite coating had dense and homogeneous structure, as well as a metallurgical bonding with the substrate. With the increase of Cr₃C₂ content, volume of chromium-containing compounds in the composite coating increased, microhardness increased and microstructure refined. The thermal physical parameters results showed that Ni60+ 50wt% Cr₃C₂ composite coating was overall worse than W₆Mo₅Cr₄V₂, but had a higher hot yield strength to alleviate hot fatigue and surface hot wear of hot forging die during hot forging and thus improve the service life of hot forging die.     

3-D transient numerical simulation on the process of laser cladding by powder feeding

A 3-D transient mathematical model for laser cladding by powder feeding was developed to examine the macroscopic heat and momentum transport during the process, based on which a novel method for determining the configuration and thickness of cladding layer was presented. By using Lambert-Beer theorem and Mie‘s theory, the interaction between powder stream and laser beam was treated to evoke their subtle effects on heat transfer and fluid flow in laser molten pool. The numerical study was performed in a co-ordinate system moving with the laser at a constant scanning speed. A fixed grid enthalpy-porosity approach was used,which predicted the evolutionary development of the laser molten pool. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. The results obtained by the simulation were coincident with those measured in experiment basically.