Ni、Cr对Fe-Ni-Mn-C-Si系合金组织和摩擦磨损性能的影响

采用熔炼法制备出新型高耐磨Fe-xNi-10Mn-4C-4Si系同体自滑润材料,研究了元素Ni和Cr对合金凝同组织及摩擦磨损性能的影响.结果表明,几种合金的凝固组织均由奥氏体基体、石墨、碳化物组成;随着Ni含量的增加,合金中石墨面密度逐渐增大,碳化物形成数量逐渐减少,材料的摩擦系数有所下降;ω(Ni)＜12%时,3%的Cr加入量使凝同组织中碳化物的数量大幅度增加,合金的耐磨性能大幅度提高.其中Fe-8Ni-10Mn-3Cr-4C-4Si合金的摩擦系数最小(0.18),磨损率仅为QT500球墨铸铁的1/10.     

Mn含量对高强韧TWIP球墨铸铁组织和性能的影响

采用熔炼法制备了3种锰含量的Fe-xMn-3.5C-3Si-3Cu-8Ni(x=10、13、16)合金铸铁,铸铁铸态组织为奥氏体基体上分布着球形石墨和碳化物.随着锰含量提高,凝固组织中碳化物数量增多,经1 050℃保温10h固溶处理后,获得奥氏体与石墨两相组织.经过拉伸变形,奥氏体基体上出现大量形变孪晶,铸铁表现出极高的强度和塑性.研究表明,这种铸铁的高强韧性源于形变过程中的TWIP效应,锰含量越高,形变孪晶越密集,TWIP效应越显著,铸铁的综合力学性能越优异.当锰含量为16％时,抗拉强度达到最大值726.5 MPa,伸长率也高达29.36％,抗弯强度和冲击韧度也分别增加到1423 MPa和161.5 J·cm-2,综合力学性能远高于其他同类型普通球墨铸铁.     

Mn和Ce对Fe-Ni-Mn-C-Si-Ce系合金组织和性能的影响

采用熔炼法制备出新型高耐磨的Fe-20Ni-xMn-3.5C-2.5Si系固体自润滑材料,研究稀土元素Ce对Fe-20Ni-xMn-3.5C-2.5Si系合金中石墨的球化作用及Mn含量对力学性能及摩擦磨损性能的影响。结果表明：随着Mn含量的增加,合金凝固组织中奥氏体的硬度逐渐增大,特别是Fe-20Ni-xMn-3.5C-2.5Si-0.75Ce系合金在摩擦过程中的表面硬度大幅度提高,呈现出高锰钢特有的表面加工硬化性质,通过TEM可以观察到磨损表面生成孪晶型马氏体;添加0.75%（质量分数）的稀土Ce可以使结晶的石墨球化,使抗拉强度和抗弯强度大幅度提高,大约比未经球化处理的提高3～5.8倍;稀土Ce的加入可以促进Fe1.1Mn3.9C2型碳化物的生成,使材料的耐磨性进一步提高,其中Fe-20Ni-16Mn-3.5C-2.5Si-0.75Ce合金的磨损率最低,大约是QT500球墨铸铁的1/13。     

高强韧TWIP铸铁的形变组织与力学性能

采用熔炼法制备出新型Fe-15Ni-12Mn-3.5C-2.5Si高强韧合金铸铁,该合金铸铁经高温固溶碳原子后,表现出高的塑性变形能力,连续冷轧变形量可达50%.拉伸试验结果表明,轧制后的试样经再高温固溶处理,合金的抗拉强度为730.81 Mpa.伸长率高达20%,是同类型QT700-2球墨铸铁的伸长率的lO倍,并具有较高的加工硬化特性.研究表明,该合金铸铁经固溶处理后组织由奥氏体、球状石墨及少量碳化物组成,良好的塑性是通过奥氏体基体密集孪生切变实现的,其高塑性源于TWIP效应;提高固溶处理温度,铸铁的抗拉强度略有降低而塑性大幅度提高.这种高强韧球墨铸铁合金对于制备减振降噪、安全性高的发动机曲轴、主轴等结构件具有重要的应用前景.     

Ni对高锰奥氏体球墨铸铁组织和性能的影响

为减少奥氏体铸铁中镍的添加量,研究了3种不同镍含量的Fe-13Mn-3.5C-3Si-3Cu-xNi高锰奥氏体球墨铸铁.铸铁经固溶处理后,奥氏体基体上的碳化物数量随镍含量的降低增多,抗拉强度、抗弯强度、伸长率以及冲击韧度均下降.镍含量为4％和8％时,铸铁表现出优异的综合力学性能,其较高的强度和塑性源于形变过程中的TWIP效应.随着镍含量从8％降为0,铸铁的摩擦系数和磨损率先增大后减小,其主要磨损机理由粘着磨损变为磨粒磨损.研究表明,为保证奥氏体球铁的综合性能,合金中需保留少量的镍元素.     

Al含量对Fe-xAl-4.0C-3.5Si合金组织及性能的影响

采用熔炼法制备了Fe-xAl-4.0C-3.5Si(x=6.3,7.4,8.9,11.1)系高温固体自润滑材料,研究了Al加入量对合金组织、力学性能及摩擦磨损性能的影响.结果表明:随着Al加入量的降低,合金中α-Fe(Al)固溶体的量增多,Fe3AlC0.5化合物的量减少,有利于改善材料的冲击韧度并提高合金的三点弯曲强度.Al加入量越少,凝固组织中石墨的面密度越大,可以减弱Al对液态合金中碳原子的排斥作用,有利于减小摩擦因素.其中Fe-7.4Al-4.0C-3.5Si合金因具有高的石墨面密度和Fe3AlC0.5硬质相均匀分布的组织特点,其耐磨与减摩性能最好,经900 ℃、15 h退火处理后,摩擦因数保持在0.32的较低水平,磨损率是QT400-18L球墨铸铁的1/5.     

等温淬火对含铬球墨铸铁组织及性能的影响

研究了等温淬火工艺对含铬球墨铸铁组织、硬度、冲击性能和耐磨性的影响。结果表明：奥氏体化温度升高,能促进球状石墨长大,增加残留奥氏体含量。淬火后组织主要为球状石墨、针状贝氏体、含铬碳化物及残留奥氏体。当淬火等温温度在240～270 ℃,随着等温温度升高,试样硬度和耐磨性均降低;在240 ℃等温时冲击韧度较低,继续升高等温温度,冲击韧度先增大后降低;当试样经910 ℃×80 min奥氏体化、270 ℃×180 min等温淬火后,含铬球墨铸铁的硬度可达54.1 HRC、冲击韧度αk可达8.1 J·cm-2,有较好的耐磨性。     

5CrNiMo模具钢的强韧化热处理工艺研究

对5CrNiMo模具钢分别采用820~940℃不同淬火温度处理,对比分析了不同淬火温度对其组织、耐磨性以及冲击韧度的影响规律。结果表明,820~880℃温度范围内淬火时,随着淬火温度的提高,基体中的孪晶马氏体及残留奥氏体逐渐减少,板条状马氏体及粒状碳化物逐渐增多,耐磨性及韧性逐渐提高,冲击断面逐渐形成较小较深的断裂韧窝。当淬火温度达到880℃时,基体表现为板条马氏体及均匀分布的粒状碳化物,耐磨性及韧性最佳。900~920℃淬火时,随着淬火温度提高,基体中的残留奥氏体逐渐增多,粒状碳化物逐渐减少,耐磨性及冲击韧度降低。     

冷轧变形对Fe-15Ni-12Mn-3.5C-2.5Si合金组织及性能的影响

利用光学显微镜、透射电子显微镜、X射线衍射和HB-3000B型布氏硬度计对Fe-15Ni-12Mn-3.5C-2.5Si合金在不同冷轧变形量条件下的组织和性能进行了分析和研究.实验表明,随变形量的增大,晶内出现大量的位错缠结组织.晶粒细化为微晶和纳米晶.合金硬度随变形量的增加而增大.说明位错硬化机制和纳米晶、非晶态的产生是Fe-15Ni-12Mn-3.5C-2.5Si合金产生应变硬化的原因.     

热处理工艺对Fe-12Cr马氏体钢组织与力学性能的影响

对Fe-12Cr马氏体钢包壳管材分别进行980～1050℃下保温15～30 min正火处理,随后在730～790℃温度下进行2 h回火处理,研究不同热处理工艺对Fe-12Cr马氏体钢包壳管材微观组织、室温和高温力学性能的影响。结果表明:正火处理后,冷轧Fe-12Cr马氏体钢的组织为板条马氏体,冷轧态的碳化物粒子会部分固溶于马氏体基体中;随正火温度的升高,残余碳化物的含量降低,且原奥氏体晶粒尺寸会增大(从980℃的9μm增至1050℃的12μm);回火处理后,马氏体基体上重新析出细小碳化物粒子,且随回火温度增加,碳化物粒子会发生粗化,平均尺寸为0.2～0.28μm,而马氏体板条间距几乎不随回火温度发生变化。Fe-12Cr马氏体钢经过1050℃×15 min正火+760℃×2 h回火处理后具有最佳的综合力学性能,其在600℃下的屈服强度为270 MPa,伸长率为40%;此时合金的碳化物粒子体积百分数最高,约为4.5%。     

镍-铁-石墨-硅自润滑材料及其性能

采用熔炼法制备出镍-铁-石墨-硅自润滑材料,并研究了铁含量对镍-铁-石墨-硅自润滑材料的力学性能、干摩擦磨损性能及油润滑摩擦磨损性能的影响.结果表明:随着铁含量的增加,合金中石墨量逐渐增多,自润滑性能逐渐提高,材料的冲击韧性和抗拉强度逐渐降低,硬度值先减小后增大;材料的干摩擦因数和油润滑摩擦因数均随着铁含量的增加而逐渐降低,磨损率随着硬度值的增大逐渐减小,其中Ni-60Fe-3.5C-1Si合金(质量分数,%)的摩擦因数最小,干摩擦因数和油润滑摩擦因数分别保持在0.18和0.05.     

粒化处理对Fe-1．4C-15Cr合金组织与性能的影响

对Fe-1．4C-15Cr合金分别进行了粒化处理（水淬＋回火）。借助光学显微镜、XRD、冲击韧性和硬度测试，研究粒化处理对其性能的影响。结果表明，粒化处理后，其显微组织中连续网状的合金碳化物明显溶解，大部分粗大的网状结构己减少或消失，合金碳化物以不连续的短棒状或颗粒状均匀分布在基体中，Fe-1．4C-15Cr合金的硬度由32．5HRC提高到40．9HRC，而韧性由9．1J·cm-2提高到10．1J·cm-2。     

Effects of silicocalcium on microstructure and properties of Mg-6Al-0.5Mn alloy

1 Introduction Magnesium alloys are attractive for applications in the automobile, aerospace and electronic industries due to their light mass, high stiffness, high specific strength, good dimensional stability and damping capacity. It is the lightest sp…     

The corrosion behavior of Fe-based shape memory alloys

Fe-30Mn-6Si, Fe-30Mn-6Si-5Cr and Fe-13Mn-5Si-12Cr-5Ni shape memory alloys were prepared by a VIM technique. The various corrosion tests were conducted to investigate the corrosion behaviors of these alloys. Experimental results show that in 3.5% NaCl solution, the Fe-13Mn-5Si-12Cr-5Ni alloy had the best chemical corrosion resistance, whereas the Fe-30Mn-6Si-5Cr alloy was locally attacked, forming many corrosion pits after immersion test. In addition, the detachment of the corrosion product covering the Fe-30Mn-6Si alloy caused an abrupt increase in the weight loss. After 2 h of heat treatment at 1000 °C, the corrosion potential of the Fe-30Mn-6Si alloy increased due to the formation of α-ferrite, while the Fe-30Mn-6Si-5Cr alloy became more active. In the stress-corrosion cracking test, the Fe-13Mn-5Si-12Cr-5Ni alloy, having the highest fracture stress in the atmosphere among these alloys, exhibited the largest decrease in fracture stress in the saturated H₂S solution due to the existence of α-martensite.     

激光熔炼Ti5Si3／NiTi金属间化合物合金的组织及耐磨性

设计并利用激光熔炼技术制备出了以Ti5Si3为增强相、以NiTi为基体的金属间化合物新型耐磨合金，研究了增强相Ti5Si3的含量对合金显微组织、显微硬度及耐磨性能的影响。结果表明，随Ti5Si3含量的增加，合金显微组织由亚共晶向共晶、过共晶转化，增强相Ti5Si3由细层片状共晶相向块状初生相转变，合金显微硬度随之显著提高；在室温干滑动磨损条件下，Ti5Si3／NiTi金属间化合物合金具有优异的耐磨性，并随Ti5Si3增强相的增加而显著提高。Ti5Si3增强相的高硬度和NiTi基体的高韧性及伪弹性效应是该合金具有优异耐磨性能的主要原因。     

Precipitation of Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

Ferritic heat resistant steels involving precipitation of intermetallic phases have drawn a growing interest for the enhancement of creep strength, while the brittleness of the intermetallic phases may lower the toughness of the alloy.Therefore, it is necessary to optimize the dispersion characteristics of the intermetallics phase through microstructural control to minimize the trade-off between the strength and toughness. The effects of α-Fe matrix substructures on the precipitation sequence, morphology, dispersion characteristics, and the stability of the intermetallic phases are investigated in Fe-Cr-W-Co-Si system. The precipitates of the Si-free Fe-10Cr-I.4W-4.5Co (at%) alloy aged at 873K are the R-phase but those of the Si-added Fe-10Cr-1.4W-4.5Co-0.3Si (at%) alloy are the icosahedral quasicrystalline phase. The precipitates in both the Si-free and Si-added alloys aged at 973K are the Laves phase. Matrix of the alloys is controlled by heat treatments as to provide three types of matrix substructures; ferrite, ferrite/martensite mixture and martensite. The hardening behavior of the alloys depends on the matrix substructures and is independent of the kinds of precipitates. In the alloys with ferrite matrix, the peak of hardness during aging at 873K shifts to longer aging time in comparison with that in the alloys with lath martensite matrix which contain numbers of nucleation sites.     

Microstructure and wear resistance of highchromium cast iron containing niobium

In the paper, the effect of niobium addition on the microstructure, mechanical properties and wear resistance of high chromium cast iron has been studied. The results show that the microstructure of the heattreated alloys is composed of M7C3 and M23C6 types primary carbide, eutectic carbide, secondary carbide and a matrix of martensite and retained austenite. NbC particles appear both inside and on the edge of the primary carbides. The hardness of the studied alloys maintains around 66 HRC, not significantly affected by the Nb content within the selected range of 0.48%-0.74%. The impact toughness of the alloys increases with increasing niobium content. The wear resistance of the specimens presents little variation in spite of the increase of Nb content under a light load of 40 N. However, when heavier loads of 70 and 100 N are applied, the wear resistance increases with increasing Nb content.     

On structure property correlation in high strength tungsten heavy alloys

Detailed structure-property correlation has been carried out in high strength tungsten heavy alloys. Alloys of compositions 90W-6Ni-2Fe-2Co, 89W-6Ni-2Fe-3Co, 89.5W-6Ni-2Fe-2Co-0.5Mo, 89.75W-6Ni-2Fe-2Co-0.25Mo, 90W-6Ni-1.5Fe-2.5Co and 90W-6Ni-1Fe-3Co have been prepared by liquid phase sintering followed by large deformation during thermo mechanical processing and studied for microstructure and mechanical properties. Despite differences in composition, higher volume fraction of matrix and lower W-W contiguity in the microstructure result in superior tensile strength and impact toughness. Increasing W content in the matrix enhances mechanical properties by imparting solid solution strengthening, increasing the matrix volume fraction and reducing W-W contiguity. The alloy 90W-6Ni-1Fe-3Co shows superior balance of properties with ultimate tensile strength of 1600 MPa and average impact toughness of 121 J/cm².