高性能渗碳轴承钢的组织与性能

 研究了热处理工艺对渗碳轴承钢组织、力学性能的影响规律,并探讨了强韧化机制。研究表明,随着淬回火温度升高和回火次数增加以及采用深冷工艺,渗碳轴承钢的强度与硬度增加,冲击韧性值下降。采用910℃淬火和180℃二次回火,轴承钢材料性能可达到硬度HRC452,抗拉强度Rm为1450MPa,屈服强度ReL为1240MPa,AKU为105J,残余奥氏体的体积分数控制在1%以下。试验钢良好的强韧性配合主要来自于晶粒的细化、超细马氏体板条和均匀弥散的细小碳化物的析出;尺寸稳定性的效果主要是残余奥氏体量的控制。     

热处理工艺对高C-Cr高强耐磨钢组织和性能的影响

设计了一种高C-Cr高强耐磨钢,测试了末端淬透性,研究了不同热处理工艺对微观组织演变和性能的影响,测试了力学性能和耐磨损性能,利用SEM和TEM表征了微观组织。试验结果表明,随距离淬火端距离的增大,试验钢的硬度呈现单调递减的趋势,0~2.5 cm为硬度平缓降低阶段,布氏硬度在63~65HRC的区间。马氏体淬火+回火处理后,试验钢基体组织主要为马氏体板条,板条尺寸大小不一。经贝氏体等温淬火处理后,贝氏体板条相互平行,板条尺寸平均。贝氏体板条间存在薄膜状的残留奥氏体,贝氏体板条内部存在长度为100~150 nm的碳化物析出相,析出相与贝氏体板条呈60°取向排列。磨损过程中,达到800转时,马氏体基体试验钢失重168 mg,贝氏体基体失重192 mg,增加了14.28%,马氏体基体的耐磨损性能更高。而贝氏体基体的力学性能却明显高于马氏体基体,屈服强度达到1 955 MPa,抗拉强度达到了2 485 MPa,伸长率仍然达到了7%。     

马氏体时效钢离子氮化工艺和渗层的研究

本文对超高强度18Ni马氏体时效钢离子氮化前后的尺寸稳定性和渗层进行了研究。预时效和氮化工艺选择恰当使氮化前后有高度的尺寸稳定性。通过金相,X光相分析,俄歇谱仪,扫描电镜和透射电镜等,研究了渗层的组织、结构及相成分。采用了单侧减薄的制膜技术,观察了化合物的精细结构。18Ni马氏体时效钢经离子氮化后,表面硬度可达HRC62以上,渗层深度大于0.2mm,扩散层内除有分布均匀的氮化物外,还有细而密的Ni_3Mo存在,表面化合物层是由晶粒细小,且有一定方向性的γ′相组成。     

高温渗碳轴承钢旋弯疲劳裂纹萌生与扩展行为

 为了提高航空轴承的服役寿命,借助QBWP-10000X型旋转弯曲疲劳试验机,研究了高温渗碳轴承钢的旋转弯曲疲劳性能和裂纹萌生扩展行为。结果表明,钢的中值疲劳强度达到913.3 MPa。有效渗层中大量M₂₃C₆和少量M₆C碳化物显著提高了试验钢的表面硬度,渗层不同碳浓度导致马氏体先后发生相变而形成408 MPa表面压应力,进而提高了钢的疲劳性能。疲劳裂纹主要萌生在表面缺陷和次表面碳化物,分别占比71.4%和 28.6%。萌生裂纹缺陷特征尺寸及承载应力对应力强度因子和循环次数影响显著,深犁沟形状由于涉及应力集中而直接影响疲劳循环次数,承受相同加载应力碳化物特征尺寸越大,循环次数越低。裂纹萌生后沿渗碳层碳化物边界快速扩展同时向芯部缓慢扩展,最后在试样疲劳源对侧近边缘区域发生准解理和韧性混合断裂。     

20CrMnTi钢有无稀土渗碳热处理表面强化层的组织及性能研究

20CrMnTi钢作为一种常规渗碳钢,广泛应用于机械、汽车等行业。本文以20CrMnTi钢材料为研究对象,对比研究了普通热处理、渗碳热处理、稀土渗碳热处理不同表面热处理工艺条件下的表面强化层的组织及性能。结果如下:在化学热处理中加入稀土元素在化学热处理中起到催渗的作用,可以有效的增加渗层深度、表面硬度和耐腐蚀性。对比实验中不同热处理的表层硬度,稀土含量为5%的稀土渗碳热处理在加强表面硬度上是效果最显著的。     

H13钢碳化物析出型渗碳(CDC)处理

对H13钢的CDC处理进行了研究，用金相显微镜及扫描电子显微镜分析了渗碳层的组织形貌，用X射线衍射分析了碳化物的组成。确定了H13钢在950℃ CDC处理的最佳碳势为ω[C]＝1.2%；可获得经水淬后的淬层组织为马氏体基体上弥散分布的碳化物，主要碳化物是颗粒平均尺寸为250nm的Cr7C3，渗层厚度达到550μm，最高硬度达到1250Hm。与氮化处理的H13钢模具做了耐磨性比较，其耐磨性能优于氮化处理。     

高能喷丸对Ti-6Al-4V钛合金渗碳层耐磨性的影响

为改善Ti-6Al-4V钛合金的硬度和耐磨性能,利用高能喷丸(HESP)与渗碳复合工艺在合金表面制备强化层。首先对试样进行高能喷丸处理,然后利用无氢渗碳方法对试样的喷丸面进行渗碳。对渗碳后的试样进行微观组织观察、物相分析和元素含量测定,并测试试样的硬度和摩擦磨损性能,研究高能喷丸对Ti-6Al-4V合金渗碳行为和渗碳层性能的影响。结果表明:与直接无氢渗碳试样相比,经过高能喷丸处理后试样的渗碳层厚度以及渗碳层中C元素含量和TiC含量都得到了明显提高。经过复合工艺处理后,试样表层硬度达到了HV 1061,而直接渗碳试样为HV 928. 1,并且在距表层150μm深度范围内其硬度都高于直接无氢渗碳试样;试样的磨损性能也得到了明显提高,在相同条件下磨损量仅为直接渗碳试样的32%。     

16Cr14Co12Mo5耐热耐蚀轴承钢强韧化机制的研究

 对16Cr14Co12Mo5耐热耐蚀轴承钢在1050℃高温淬火后,在490～540℃两次回火后的组织性能以及强韧化机制进行研究。结果表明：随着回火温度的升高,抗拉强度Rm逐渐增加,最大时超过了1900MPa,屈服强度Rp0.2在500℃回火后达到1400MPa,随后逐渐减小;断面收缩率和伸长率略有减小,而硬度略有增长。材料强韧化主要源于高位错板条马氏体以及其中残余奥氏体薄膜和沉淀析出的碳化物和金属间化合物。采取适宜淬回火工艺制度所导致弥散析出的碳化物和金属间化合物是试样的强度和韧性达到最佳配合的关键。     

NM400高强度低合金耐磨钢的组织与性能

采用Ti-Cr-B微合金化成分设计、奥氏体再结晶区直接轧制及淬火加低温回火的热处理工艺,开发出低成本的NM400级别高强度、高韧性的低合金耐磨钢板.利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)等对其组织、性能、断口形貌及析出物进行了研究.结果表明:试验钢的组织主要为高密度位错板条马氏体及分布在板条上的碳化物;抗拉强度≥1400 MPa,表面硬度≥HV450,-40℃冲击功在60 J以上;钢板淬透性好,厚度方向硬度分布均匀;除固溶强化和细晶强化外,马氏体板条上的大量位错以及10 nm左右的Ti(C,N)析出颗粒起到强烈的硬化作用;经能谱分析,断口韧窝处存在的第二相粒子主要为MnS和Al2O3颗粒,最大尺寸在2 μm左右.     

P20塑料模具钢预硬化热处理工艺的研究

通过金相显微镜、扫描电镜和维氏硬度计,对P20塑料模具钢进行了显微组织观察和硬度测定,研究了在淬火温度、淬火介质、回火温度等不同预硬化热处理工艺参数条件下得到的组织及其硬度变化规律。结果表明:随着回火温度升高,水淬和空淬钢组织中的板条马氏体和贝氏体逐渐减少,铁素体增加并长大,碳化物增多,硬度逐渐降低,板条间的薄片状M/A组元、铁素体中较高的位错密度以及细小碳化物保证了水淬钢在620℃回火时具有较高的硬度,最终确定了保证该钢种最佳预硬化效果的工艺参数。     

Effect of heat treatment on microstructure and mechanical properties of plastic mold steel 10Ni2Cr2MnCuMoVAl

The effects of solution and aging treatment on microstructure and mechanical properties of 10Ni2Cr2MnCuMoVAl plastic mold steel were experimentally studied. The results show that the dominant microstructure of 10Ni2Cr2MnCuMoVAl steel after solid solution treatment is lath martensite, and higher solution temperature results to larger width of martensite, while the highest value of hardness could be obtained after solution treatment at 890??. After aging, the microstructure consists of lath martensite, granular bainite and carbides. For steel aged at 460-520??, the strength of the material gradually increased with higher aging temperature, while the toughness decreased gradually. When the temperature exceeded 520??, higher temperature led to decreased hardness and increased toughness. Compared the mechanical properties of steel aged at 540?? for different time, the test steel reached the peak of mechanical properties at 8h. By comparing the mechanical properties of the test steels after different aging treatments, the optimized heat treatment process of 10Ni2Cr2MnCuMoVAl steel is solution treatment at 880?? for 2h with air cooling and tempering temperature at 540?? for 4h with air cooling.     

V和Nb对12％Cr铁索体钢微观组织和蠕变特性的影响

利用光学显微镜和透射电子显微镜以及光电子能谱分析方法,研究了元素V和Nb对12％Cr铁素体耐热钢的微观组织和析出相的形态和分布的影响.结果表明:添加V和Nb的铁素体钢具有更窄的马氏体板条组织;附于MX型碳氮化物生长的M23C6碳化物呈细小的针状或短棒状析出,而单独析出的M23 C6尺寸较大,呈椭圆形.这些组织上的优化和MX型碳氮化物的弥散析出有效抑制了回火马氏体组织的回复和再结晶,提高了铁素体钢的蠕变抗力.     

Microstructure and Mechanical Properties of Martensitic Stainless Steel 6Crl5MoV

 Martensitic stainless steel containing Cr of 12% to 18% (mass percent) are common utilized in quenching and tempering processes for knife and cutlery steel. The properties obtained in these materials are significantly influenced by matrix composition after heat treatment, especially as Cr and C content. Comprehensive considered the hardness and corrosion resistance, a new type martensitic stainless steel 6Cr15MoV has been developed. The effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel is emphatically researched. Thermo-Calc software has been carried out to thermodynamic calculation; OM, SEM and TEM have been carried out to microstructure observation; hardness and impact toughness test have been carried out to evaluate the mechanical properties. Results show that the equilibrium carbide in 6Cr15MoV steel is M23C6 carbide, and the M23C6 carbides finely distributed in annealed microstructure. 6Cr15MoV martensitic stainless steel has a wider quenching temperature range, the hardness value of steel 6Cr15MoV can reach to HRC 608 to HRC 616 when quenched at 1060 to 1100 ℃. Finely distributed carbides will exist in quenched microstructure, and effectively inhabit the growth of austenite grain. With the increasing of quenching temperature, the volume fraction of undissolved carbides will decrease. The excellent comprehensive mechanical properties can be obtained by quenched at 1060 to 1100 ℃ with tempered at 100 to 150 ℃, and it is mainly due to the high carbon martensite and fine grain size. At these temperature ranges, the hardness will retain about HRC 592 to HRC 616 and the Charpy U-notch impact toughness will retain about 173 to 20 J. A lot of M23C6 carbides precipitated from martensite matrix, at the same time along the boundaries of martensite lathes which leading to the decrease of impact toughness when tempered at 500 to 540 ℃. The M3C precipitants also existed in the martensite matrix of test steel after tempered at 500 ℃, and the mean size of M3C precipitates is bigger than that of M23C6 precipitates.     

17Cr2Ni2钢渗碳后的组织及力学性能

将17Cr2Ni2钢高温锻造,然后在850～870℃进行油淬和200℃回火处理后,进行渗碳处理,研究渗碳后材料的组织和力学性能。结果表明：渗碳层的组织为细小的回火马氏体,渗层均匀,厚度约1.3mm左右,渗碳后材料具有较高的力学性能,抗拉强度平均值为1 400MPa,屈服强度平均值为1 150MPa,表面硬度平均值为61...     

The Investigation for Development on Precipitation Phases in 25Co15Ni11Cr2MoE Steel during Tempering

The evolution law of precipitated alloy carbides and reverted austenite in a high Co-Ni secondary hardening ultra-high strength 25Co15Ni11Cr2MoE steel tempered at 300??~ 660?? after quenched has been studied by means of transmission electron microscopy (TEM) and X ray diffraction (XRD) in this paper. The results show that the precipitate order of alloy carbides with the increasing of tempering temperature from 300?? to 600?? in experimental steel is: dispersed ??-carbides?? lamellar alloy cementites?? dispersed M2C carbides?? coarse M23C6 carbides. When the experimental steel tempering at 495??, fine M2C carbides precipitated on the lath martensite matrix. Meanwhile, coarse lamellar alloy cementites that precipitated during the early tempering stage has all dissolved, and reverted austenite precipitated at the boundaries of lath martensite and grows up into thin-film sharp along the lath boundaries. When the tempering temperature rose to 530??, the content of reverted austenite continues to increase, but the morphology of reverted austenite changed from thin-film to strip or block. When the tempering temperature rose to 530??, the content of reverted austenite in the steel reaches maximum value.     

45Mn2V/Q345复合锯片用钢回火工艺研究

对复合锯片用钢进行了不同温度和保温时间的回火处理,分别测定和观察了覆层与基板的硬度和显微组织。结果表明:Q345钢基板的板条马氏体在回火过程中逐渐粗化,但其基本特征经较高温度回火后仍能保留下来,而覆层45Mn2V钢的针状马氏体退化速度较快,400℃回火后已观察不到针状特征,导致回火后其硬度下降的趋势大于Q345钢基板,因此复合板的回火温度不宜超过400℃。另一方面,由于碳含量较高,45Mn2V钢覆层在回火过程中碳化物的析出较快且析出量较多,故经过8 h回火后仍能保持高的硬度,而Q345钢基板已经发生明显的软化,因此860℃保温5 min油淬,360～390℃保温6 h回火可获得最佳性能。     

Observation and Analysis of the Microstructure in CarburizedSurface Layer of Steel 20Cr2Ni4A Treated with ConventionalAnd Rare Earth Carburizing Processes

ＯｂｓｅｒｖａｔｉｏｎａｎｄＡｎａｌｙｓｉｓｏｆｔｈｅＭｉｃｒｏｓｔｒｕｃｔｕｒｅｉｎＣａｒｂｕｒｉｚｅｄＳｕｒｆａｃｅＬａｙｅｒｏｆＳｔｅｅｌ２０Ｃｒ２Ｎｉ４ＡＴｒｅａｔｅｄｗｉｔｈＣｏｎｖｅｎｔｉｏｎａｌＡｎｄＲａｒｅＥａｒｔｈＣａｒｂｕｒｉｚｉ...     

钢液中废钢熔化行为的热模拟试验

 废钢熔化过程是控制转炉炼钢过程温度轨迹和废钢比以及电弧炉炼钢能耗和生产率的限制因素。为研究废钢在钢液中的熔化机理,考虑了废钢熔化过程中的传热传质过程,并基于废钢熔化理论分析模型,在实验室中进行了废钢熔化的热模拟试验。研究结果表明,当钢棒浸泡在熔池中较短时间时,钢棒外层形成凝固层。由于激冷效应,在凝固层与钢棒之间形成气隙;在钢棒浸泡过程中,钢棒的组织发生变化,由珠光体和铁素体转变为奥氏体。水淬后,渗碳层中生成针状马氏体,钢棒内层形成板条马氏体。当钢棒在熔池中浸泡时间过长时,钢棒外层形成高温铁素体和液相。     

Vacuum carburization of 12Cr2Ni4A low carbon alloy steel with lanthanum and cerium ion implantation

As bearing parts, 12 Cr2 Ni4 A is expected to have high hardness and excellent fatigue strength, so carburizing is employed to improve the inherit properties of 12 Cr2 Ni4 A. However, the traditional carburizing is limited by poor microstructure distribution and low rate of carburizing. The rare earth ion implantation is known to help improving the properties of tribology, corrosion resistance and oxidation resistance of metal. In this article, the RE implantation is employed to assist the carburizing. Lanthanum and cerium ion implantations are initially used to assist 12 Cr2 Ni4 A low pressure vacuum carburization.The microstructure, content of retained austenite, hardness, thickness of layer and carbon diffusion were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) and Rockwell/Vickers hardness tester, respectively. It was shown that lanthanum and cerium implantations can improve structure of the vacuum carburizing layer, and enhance the uniformity of carbon element distribution on the carburized surface. Meanwhile the RE implantation plays a positive role in promoting the surface hardness and carburized rate. The lanthanum element has more significant effect on surface hardness and content of retained austenite than cerium element. The surface hardness of lanthanum element implanted layer was 62.9 HRC with 9.6% content of retained austenite, while the carburizing rate of cerium implanted layer increased by 12.4%.     

热处理对2 000 MPa超高强度不锈钢组织和性能的影响

 运用Thermal-calc热力学软件、光学显微镜（OM）、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等手段研究了热处理工艺对一种新型的超高强度不锈钢微观组织及力学性能的影响。结果表明,经过固溶处理后钢的基体为高密度位错的板条马氏体组织;强度随着时效温度的升高而逐渐升高,在520～540 ℃时可达到2 000 MPa,且冲击吸收功在540 ℃时达到最大值37 J。此时在板条马氏体上析出大量、细小、弥散以μ相为主的第二相,同时在板条与板条界面上有块状的逆转变奥氏体生成,这是该钢具有超高强度与高韧性的主要原因。