激光-电磁场复合强化对45钢硬度的影响

研究了旋转磁场对45钢表面硬度的影响规律。利用自制的磁能强化装置对经过激光相变硬化的45钢进行磁化处理。研究了不同的磁场频率、磁化时间对45钢硬度的影响规律。通过金相显微镜观察45钢的金相组织,分析其性能得到提升的微观机理。试验结果表明:在合适的磁化工艺参数条件下,45钢的表面硬度均得到不同程度的提高。旋转磁场能降低马氏体激活能,促使部分残余奥氏体转换为马氏体,位错重新分布并趋于均匀化,材料的显微组织变得致密。     

激光表面相变硬化对T10微观组织与性能的影响

采用激光相变硬化方法对T10钢进行表面处理,研究了不同激光功率、扫描速度、光斑直径等参数对T10钢的微观组织、划痕硬度及其力学性能的影响,并采用XRD和SEM/DES分析了T10钢的相组成、微观结构。结果表明:激光相变硬化是对T10钢进行相变处理的有效方法,选用合理的加工参数,可以获得组织均匀致密的硬化层,随着距表面距离的增加,马氏体数量逐渐增多,硬度也逐渐增加,当激光功率P=1.2 kW,扫描速度v=20 mm/s,光斑直径d=5 mm时,其平均划痕硬度可达到896,较原始试样的平均划痕硬度提高了43.36%。     

TiC颗粒强化型马氏体耐磨钢的性能研究

采用模铸、连铸两种工艺工业化试制一种TiC颗粒强化型马氏体耐磨钢,分析了TiC颗粒的析出规律,对比研究了试验钢与传统马氏体耐磨钢的组织、力学性能及耐磨性能。试验结果表明:凝固速度越大,TiC析出相越细;轧制压缩比越大,颗粒分布越均匀;TiC颗粒强化马氏体钢强度与传统马氏体钢相当,韧性有所降低;微米级的TiC可以有效提高材料的磨粒磨损性能,试验钢磨损失重仅为同等硬度传统马氏体钢的70%;耐磨性能的提高主要是因为在磨粒磨损条件下,微米级TiC硬质点可以破碎磨砺、钝化尖角、阻断磨痕。     

铁基粉末冶金材料的表面激光热处理

激光自二十世纪六十年代问世以来,引起了各方面的重视,七十年代初期,开始应用于金属热处理,在增加材料的耐磨性和提高材料的使用寿命方面取得了显著效果。长春光机所和第一汽车制造厂附件分厂对铁基粉末冶金材料进行了表面激光热处理试验。激光热处理是表面局部热处理,具有能量密度高、加热和冷却速度极快等优点。通过试验证明,激光热处理后表面硬度比原始基体硬度(HV100左右)提高7倍多,硬化层深一般为0.2毫米左右,耐磨性比一般铁碳材质提高10倍以上。试样的原始组织主要为片状珠光体,经激光热处理后,激光硬化层形貌为球冠形,硬化组织除孔隙与石墨外均为隐晶马氏体,过渡区组织为细珠光体。激光热处理操作简     

中碳Cr-Mo-V钢连续冷却时的组织转变规律

采用Formastor-FⅡ全自动相变仪实现不同冷却速度,利用金相显微镜、扫描电子显微镜和透射电子显微镜,研究了45CrMoV钢在不同冷却速度下的组织转变规律以及回火温度对组织的影响。结果表明,随着冷却速度的变慢,45CrMoV钢的组织由马氏体变为马氏体、先共析铁素体、下贝氏体和粒状贝氏体的混合物。冷却速度进一步变慢,先共析铁素体数量增多,下贝氏体和粒状贝氏体总量减少,材料硬度不断下降;45CrMoV钢中的粒状贝氏体为岛状、颗粒状,也有不规则形状,下贝氏体铁素体板条比低碳钢和超低碳钢中的板条更宽,分布更分散,板条形态不规则;随着回火温度的升高,45CrMoV钢中的渗碳体由细针状变为细条状,最后长大为椭球状,材料强度下降,韧性上升。     

激光硬化粉末烧结钢的组织结构及耐磨性

两种Fe-Ni-Cr-Cu-Mo-C系粉末烧结钢宽带激光硬化处理表明,激光硬化的粉末烧结钢表面层的组织结构由马氏体、贝氏体、残余奥氏体和游离态石墨等组成.激光硬化处理显著改善了粉末烧结钢的耐磨性.     

化学成分对耐磨铸钢组织与性能的影响

为了克服高锰钢作为履带板材料具有的耐磨性能较差、力学性能较低的缺点,设计了能够作为高锰钢替代材料的一种新型双相(马氏体+贝氏体)耐磨铸钢.研究结果表明:试验钢在淬火回火态下为马氏体+贝氏体双相组织,另外还残存着极少量的残余奥氏体组织.含碳量的增加使试验钢的冲击韧性和延伸率趋向降低.随着铬含量的升高,冲击韧性在淬火回火态下升高.含质量分数为0.30%C,0.6%Cr合金的综合力学性能最优,组织为马氏体+贝氏体双相组织.经由400 h磨损试验后,在干态磨损条件下,其耐磨性能比高锰钢提高了56%,而在有腐蚀介质的湿态磨损条件下,耐磨性能比高锰钢提高了22.5%.     

新型中锰马氏体高强度钢的耐磨性能

 利用销盘式磨料磨损试验和三体冲击磨料磨损试验研究碳质量分数分别为0.12%和0.19%新型中锰马氏体高强度钢的磨损行为,并与Hardox450钢和21C钢进行耐磨性能对比。用磨损失重量表征耐磨性能,利用LOM、SEM和XRD等设备研究材料磨料磨损机制。结果表明,新型中锰钢耐磨性能与Hardox450钢及21C钢相当。在销盘式磨料磨损试验和三体冲击磨料磨损试验中,马氏体高强钢的耐磨性能与材料的硬度呈线性关系,硬度越高,材料耐磨性越好。由于锰的添加,新型中锰钢的优点不仅在于具有锰的固溶强化特性提高耐磨性能,还在于该钢的淬透性几乎与该钢的冷却速度无关,因而该钢具有大规模工业生产的潜力。     

激光处理对9Cr2钢组织的影响

用 3kW连续CO₂ 横流激光器对成分(%)为0.80~0.95C,0.40Si,0.40Mn,1.30~1.70Cr的9Cr2 钢进行激光表面热处理,分析了在激光功率1.8～2.4 kW、激光束扫描速度500～1000mm/min的激光处理后 该钢的表面组织和硬化层深度。试验结果表明,当激光束功率较大、扫描速度较小时处理后组织区域为熔化 区、相变区、热影响区和基体,硬化层厚度0.4~0.8mm; 当激光束功率较小、扫描速度较大时处理后组织区域 为相变区、热影响区和基体,硬化层深度0.2~0.6 mm     

激光表面处理对渗碳渗硼合金钢的组织与耐磨性的影响

利用连续CO_2激光器对渗碳和渗硼后的20CrNiMo和20Ni4Mo钢进行激光表面相变硬化和激光表面熔化处理,以研究激光表面处理对钢的组织与耐磨性的影响。用金相、电镜、X光及电子探针观察和分析显微组织结构、表层成分分布、磨损表面及磨屑形貌。 对20CrNiMo和20Ni4Mo钢进行多次激光相变硬化处理。结果表明,多次激光相变硬化提高了钢的耐磨性,并且显微组织与普通淬火、一次激光硬化钢有很大不同。钢经渗碳、渗硼再激光表面熔化后,表层成分组织均发生根本变化,耐磨性得到提高。渗碳钢经激光熔化后的耐磨性较低,这主要是因大量的奥氏体和渗碳体组成的共晶组织的硬度较低所致。     

铁基粉末冶金材料的激光宽带淬火

利用连续波CO2激光器，对铁基粉末冶金材料进行了宽带激光相变硬化实验。研究了激光相变硬化工艺参数对铁基粉末冶金材料的显微组织、显微硬度、硬化层深度和耐磨性的影响。结果表明，对铁基粉末冶金材料进行宽带激光淬火存在最佳的能量密度，可使硬化层分布均匀，耐磨性明显提高。     

Microstructural Aspects and Wear Behavior of Sinter Hardened Distaloy HP

Effect of cooling rate during sinter hardening on the microstructure and wear behavior of sintered steel grade Distaloy HP has been studied. Wear performances are closely related to macro and micro hardness of the materials. Dry sliding wear tests have been conducted using a reciprocating pin on flat wear testing machine under normal loads of 25, 35 and 45N and at a constant speed of 0.3 m/s. The samples were sinter hardened at different cooling rates 0.5–3 °C/s in order to investigate the influence of microstructure and hardness on wear behavior. It has been shown that, sintering process and cooling rate change the microstructure and hence the hardness and wear behavior of the material. The best wear resistance was detected at a cooling rate of 3 °C/s. At this cooling rate the material had an almost martensitic microstructure and the wear rate was some how independent of the applied load.     

Properties of 3Cr2W8V Die Steel With Striations Processed by Laser

 The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance and mechanism of thermal fatigue crack propagation in the zone processed by laser were observed and discussed. The results show that the wear resistance and thermal fatigue resistance of materials processed by laser are all better than those of the unprocessed material. The processed zone by laser plays a role in baffling wearing process and crack propagation. The pile nail effect of processed zone is the main factor for improving the wear resistance and thermal fatigue resistance of material.     

Laser Quenching of Ionic Nitrided Steel: Effect of Process Parameters on Microstructure and Optimization

The surface properties of 40CrMnMo7 steel have been increased by ionic nitriding thermo chemical treatment followed by laser quenching. Nitriding treatment increases the wear resistance and decreases the wear coefficient, guaranteeing an uniform, though shallow, hardening depth. Combining nitriding with laser quenching has been shown to increase of the hardening depth, while retaining the advantages obtained by the first treatment. In this work the effect of laser quenching parameters on microstructure and mechanical properties of 40CrMnMo7 steel have been investigated and predictive models developed suitable for further optimization of the process. DoE has been exploited to reduce the number of experiments and for evaluating by statistic methods the optimized process parameters.     

Microstructure and Property of HD Die Steel With Unsmoothed Surface With Various Laser Parameters

The reticulate unsmoothed surfaces on HD die steel, which imitate the surface of soil-burrowing animals （such as the dung beetle, earthworm, pangolin, and ant） are produced with various laser parameters. The characteristics （including width, depth, area ratio, and volume）, microstructure, and hardness of the unsmoothed units are studied. At the same time, the wear resistance of the material with an unsmoothed surface is measured. The results show that the width and volume of the unit increase, the microstructure becomes coarser, the hardness decreases, and the wear resistance improves with the increase of the current intensity and pulse duration within a certain range. However, there is little difference between the extent to which the wear resistance of the material increases and the unsmoothed surface, when the current intensity and pulse duration increase to some extent. The wear resistance of the unsmoothed material under 300 A or 20 ms is better in the experiments. The improving extent of the wear resistance lies in a combination of the characteristics, microstructure, and hardness of the unsmoothed unit. An unsmoothed material with better properties can be processed if the laser parameters are well matched.     

超音速等离子喷涂YPSZ涂层的组织及耐磨性能

为了研制一种连铸结晶器耐高温耐磨材料,采用超音速等离子喷涂法在纯铜板上制备了氧化钇部分稳定的氧化锆(YPSZ)涂层.利用X射线衍射仪、扫描电镜、彩色3D激光显微镜和图形软件(Image-pro Plus3.0)对YPSZ涂层的微观组织进行表征,通过销盘式磨损仪在室温干摩擦条件下测试了涂层的耐磨性能及化学硬化对涂层耐磨性能的影响.研究发现YPSZ涂层完全由t’-ZrO₂相组成,其断口形貌由柱状晶和一定量的部分熔融颗粒组成,截面组织形态表现出较好的完整性,涂层孔隙率为1.2%,表面粗糙度为6.457μm.磨损实验表明化学硬化前YPSZ涂层与刚玉球对磨时的摩擦因数在0.5~0.6之间,平均磨痕宽度为3638.8μm,磨损体积为1.25508×10-2mm3,磨损机制为脆性断裂导致的磨粒磨损;化学硬化后YPSZ涂层的磨痕宽度和磨损体积均有大幅降低,脆断程度也更轻,其磨损性能得到极大改善.      

Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel

High speed steel hacksaw blade blanks were laser surface melted and rapidly solidified along one edge. The laser melting resulted in complete carbide dissolution. By subsequent machining and heat treatments saw teeth were manufactured with a refined internal structure of the edges and corners. The structure was fully martensitic with a uniform and dense dispersion of small primary carbides. Sawing tests in quenched and tempered steel showed that blade life was somewhat improved, as compared to conventionally heat treated blades. The increased wear resistance is believed to be due to improved toughness along with high hardness caused by the refined carbide structure. Sawing tests in austenitic stainless steel did not give any significant improvement in performance. The effect of the altered microstructure on performance is likely to be more or less pronounced depending on application, tool and work material.     

不锈钢表面激光熔覆强化层研究现状与展望

不锈钢是推动现代工业发展的关键金属材料之一。在重载、盐雾、空化、高温等恶劣工作环境下,不锈钢材料存在耐磨损、耐腐蚀、抗空蚀、抗高温氧化等表面性能不足的问题,限制了其更为广泛的应用。激光熔覆技术是近年发展较为迅速的绿色表面改性技术,其熔覆层具有组织致密且均匀、晶粒细小、膜基结合强等优点,已被广泛应用于不锈钢表面强化领域。对影响熔覆层质量的关键工艺参数与送料方式进行研究,归纳熔覆层表面强化研究现状,总结激光熔覆技术的工业应用和新型激光熔覆复合技术,进而对激光熔覆技术发展趋势及应用前景进行展望。     

Influence of Subsurface Structure on the Linear Reciprocating Sliding Wear Behavior of Steels with Different Microstructures

The present work investigates the influence of subsurface microstructure on the linear reciprocating sliding wear behavior of a number of steels with ferrite-pearlitic, pearlitic, bainitic, and martensitic microstructures under dry unlubricated condition. The change in the underlying microstructure with depth from worn-out surface of steel sample intimately relates to the associated hardness variation and wear volume. The present paper is not about comparison of wear resistance of steels with different structures; rather it is on mutual influence of wear and substructure for individual microstructure. Inherent toughness of the matrix and ability of microstructural components to get deformed under the reciprocating action of the ball decide the wear resistance of the steels. Bainite has good amount of stability to plastic deformation. Ferrite shows severe banding due to wear action. Work hardening renders pearlite to be wear resistant. Temperature rise and associated tempering of martensite are observed during wear.     

型钢轧辊激光相变硬化策略的设计与实施

为了实现激光相变硬化工艺参数的优化选择,基于有限元仿真技术,研究了激光扫描过程中的温度场分布规律,并结合材料相变曲线,预测了轧辊淬硬层的宏观形态。进而,根据宏观表面硬度和显微组织的实验结果,确定了适于半钢材质激光强化的参数组合。经磨料磨损实验表明,半钢材质的型钢轧辊经激光强化后,其耐磨性显著提高。