新型锰铬抗磨铸铁的研制

针对目前低铬抗磨铸铁硬度低、耐磨性差的情况,以Mn对低铬铸铁进行合金化,开发了一种新型的锰铬抗磨铸铁,并通过扫描电镜分析了Mn在锰铬抗磨铸铁中的分布。实验结果表明：锰能够大幅度地提高材料铸态下的硬度,从低铬铸铁的46 HRC提高到了55 HRC,并使硬度分布均匀。     

Effect of heat treatment process on impact wear property and mechanism of SKD11 steel

The microstructure, mechanical property, phase of SKD11 steel after vacuum heat treatmentor deep cryogenic heat treatment were studied by means of OM, hardness tester, impact tester and XRD.The impact wear properties of SKD11 steel under the two heat treatments were tested by MLD- 10 dynamic load- bearing wear tester. The impact wear mechanism was also analyzed. The results show that the microstructures of SKD11 steel after the two heat treatmentsare composed of tempering martensite, retained austenite and carbide. The hardness after cryogenic treatment is 1HRC higher than that of the vacuum treatment and impact toughness decreases lightly. Under impact wear conditions, the weight loss of the sample during deep cryogenic treatment is lower than that of the vacuum treatment, which shows better wear resistance. In the studied wear time, the wear mechanism of the sample after vacuum treatment is high stress surface fatigue and abrasive wear, and the wear mechanism of the sample after cryogenic treatment is slight abrasive wear.     

Effect of Heat Treatment on Microstructure and Properties of High Boron-High Speed Steel

A new type of high boron-high speed steel (HB-HSS) with different boron content was selected for oil quenching at 1050 °C, and different temperature of tempering treatment was chosen. By using optical microscopy, scanning electron microscopy, X-ray diffraction, Rockwell hardness tester, red hard treatment and wear test, the effects of heat treatment on microstructure and properties of HB-HSS were investigated. The experimental results indicate that the quenching microstructure of HB-HSS consists of α-Fe, M₂(B, C), M₇(B, C)₃ and a few of M₂₃(C, B)₆. When the tempering temperature is lower than 500 °C, the shape of carboborides will change from discontinuous sheet to continuous net, and the uniformity in microstructure is improved, and the hardness is not changed during the process. When the tempering temperature is higher than 500 °C, the continuous net of M₂(B, C) is recovered. When the tempering temperature is higher than 600 °C, the microstructure of HB-HSS get thickened because of overheating, and the hardness get significantly reduced. With the increase of tempering temperature, the weight loss of the sample is decreased, and the wear resistance of the sample is increased. When tempering temperature exceeds 500 °C, the weight loss of the sample has an obvious increase and its wear resistance decreases. The wear resistance of the sample decreases after the red-hardness treatment. The wear loss is about 8.4 mg when the boron content is 2.0% and the tempering temperature is 500 °C, which is the best of test samples.     

Effect of Heat Treatment on Structure and Wear Re- sistance of High Chromium Cast Steel ContainingBoron

The microstructure, mechanical properties and wear resistance of high chromium cast steel containing boron after different heat treatments were studied by means of the optical microscopy （OM）, the scanning electron microscopy （SEM）, X-ray diffraction （XRD）, hardness, impact toughness, tensile and pin-on-disc abrasion tests. The results show that as cast microstructures of boron-free high chromium steel consist of martensite and a few （Cr, Fe）_7C_3 carbide, and the macro-hardness of boron-free high chromium steel is 55-57 HRC. After 0.5 mass% B was added into high chromium cast steel, as-cast structure transforms into eutectic （Fe, Cr）2B, （Cr, Fe）7 （C, B）a and martensite, and the macro-hardness reaches 58-60 HRC. High temperature quenching leads to the disconnection and isolated distribution of boride, and there are many （Cr,Fe）_23 （C,B）_6 precipitated phases in the quenching structure. Quenching from 1050 ℃, high chromium steel obtained the highest hardness, and the hardness of high chromium cast steel containing boron is higher than that of boron-free high chromium steel. The change of quenching temperature has no obvious effect on impact toughness of high chromium steel, and the increase of quenching temperature leads to tensile strength having an increasing tendency. At the same quenching temperature, the wear resistance of high chromium cast steel containing boron is more excellent than that of boron-free high chromium steel. High chromium cast steel guide containing boron has good performance while using in steel bar mill.     

Effects of chromium sources on the microstructure and properties of TiC-steel composites

The composites of low alloy steel reinforced with TiC particles (36?wt-%) were prepared by conventional powder metallurgy process in this paper. The chromium in the steel matrix was provided by pure chromium powder (PCP), low carbon ferrochrome powder, medium carbon ferrochrome powder (MCFP) and high carbon ferrochrome powder. The SEM was used to observe the particle morphology and microstructure. Density, hardness and transverse rupture strength (TRS) of the samples were tested. The results show that the composite prepared with the PCP as a chromium source has low hardness and TRS and the composites prepared with different ferrochrome powders have higher hardness and TRS. The microstructures of the samples prepared with different chromium sources have some differences and provide the differences in mechanical properties and fracture morphology. The sample prepared with the MCFP as chromium source has the highest comprehensive performance after tempering: hardness 70 HRC and TRS 1752?MPa.     

WC含量对明弧堆焊奥氏体合金显微组织及耐磨性的影响

采用金属粉型药芯焊丝自保护明弧焊制备Cr9Mn6Nb2WVSi Ti奥氏体耐磨堆焊合金,借助XRD,SEM,EDS及光学显微镜研究外加WC颗粒对其显微组织及耐磨性的影响。结果表明,随焊丝药芯中WC增加,奥氏体晶粒细化,沿晶分布的多元合金化碳化物数量增加。初生γ-Fe相原位析出了(Nb,Ti,V)C相和残留WCx颗粒,起到晶内弥散强化作用,沿晶分布的(Nb,Ti,V)C和M_6C(M=Fe,Cr,Mn,V,W)相隔断了网状或树枝状的沿晶M_7C_3相,使其细化、断续分布而提高合金韧性,减轻沿晶碳化物数量增加的不利影响。硬度和磨损测试结果显示,明弧堆焊奥氏体合金洛氏硬度仅为40~47,但其磨损质量损失低于高铬铸铁合金,具有良好耐磨性;随外加WC含量提高,奥氏体合金晶内和晶界显微硬度差异显著减小,合金表面趋于均匀磨损而改善耐磨性。该奥氏体合金的磨损机制主要是磨粒显微切削,适用于带有一定冲击载荷磨粒磨损的工况下使用。     

Wear resistance of chromium-containing matrices of diamond drilling tools

The paper examines the wear rate in friction of copper-impregnated samples produced by pressing of VK6 powder with chromium additions. The test is conducted on a cast iron disk in the presence of a wet SiC powder and on a diamond wheel without cooling. It is shown that higher chromium content insignificantly increases the sample wear rate in friction with the cast iron disk. At the same time, the wear rate abruptly decreases for the diamond wheel. The hardness of the samples does not significantly change with increasing chromium content to 6 wt.%.     

Comparison of microstructure and property of high chromium bearing steel with and without nitrogen addition

Microstructure and property of bearing steel with and without nitrogen addition were investigated by microstructural observation and hardness measurement after different heat treatment processing. Based on the microstructural observation of both 9Cr18 steel and X90N steel,it was found that nitrogen addition could effectively reduce the amount and size of coarse carbides and also refine the original austenite grain size. Due to addition of nitrogen,more austenite phase was found in X90N steel than in 9Cr18 steel. The retained austenite of X90N steel after quenching at 1 050 °C could be reduced from about 60% to about 7% by cold treatment at-73 °C and subsequent tempering,and thus finally increased the hardness up to 60 HRC after low temperature tempering and to 63 HRC after high temperature tempering. Furthermore,both the wear and corrosion resistance of X90N steel were found much more superior than those of 9Cr18 steel,which was attributed to the addition of nitrogen. It was proposed at last that nitrogen alloying into the high chromium bearing steel was a promising way not only to refine the size of both carbides and austenite,but also to achieve high hardness,high wear property and improved corrosion resistance of the stainless bearing steel.     

烧结温度对Fe-Cu-Mo-C合金组织和性能的影响

采用机械球磨混粉和真空烧结相结合的方法制备了Fe-Cu-Mo-C合金,研究了不同烧结温度对粉末冶金Fe-Cu-Mo-C合金材料的显微组织、密度、抗拉强度和摩擦磨损性能的影响。结果表明:随着烧结温度由1 000℃升高到1 100℃,Fe-Cu-Mo-C合金烧结体组织孔隙数量减少、孔隙尺寸明显降低;当烧结温度提高到1 150℃时,烧结体组织中孔隙尺寸增大。随着烧结温度升高,烧结体的密度、硬度、抗拉强度和伸长率先增大后减小,磨损量先降低后升高。最佳烧结温度为1 100℃,此时烧结体的密度为6.90 g/cm3,抗拉强度为319 MPa,洛氏硬度为34.7 HRC,磨损量为0.087 g。     

Effect of RE－Al－N on Structures and Properties of M2 Cast High Speed Steel

M 2highspeedsteel (M 2steel)isamaterialwidelyusedintoolsanddies[1,2 ] .M 2steelischarac terizedbyalongsolidificationrangeandcomplexeu tecticreactions ,whichresultsinsegregationofalloy ingelementsandformationofseveraldifferenttypesofcarbidesduringsolidification[3,4 ] .Forconventionallyprocessedhigh speedsteels ,itisinevitablethatacoarsecarbidenetworkwillbeformedduringsolidifi cation .Coarseprimarycarbidestendtoresultinun evencarbidebandsdistributionafterasubstantialamountofhotprocessing[5] .Ma…     

轧钢助卷辊和深弯辊堆焊技术研究

采用YJ356-S和YJ358-S焊丝分别堆焊修复轧钢助卷辊和深弯辊,并详细研究了堆焊工艺.助卷辊堆焊层组织为回火马氏体 少量的贝氏体和索氏体,并在马氏体基体上含有高硬度碳化物;深弯辊堆焊层组织为回火马氏体 弥散分布碳化物.回火处理后,助卷辊工作层硬度(HRC)达到59.9,深弯辊工作层硬度达到63.1.磨损试验结果显示,YJ356-S堆焊金属的相对耐磨系数为0.105,YJ358-S堆焊金属的相对耐磨系数为0.121,都具有良好的耐磨性.另外,堆焊时加入电磁搅拌,有利于提高硬度并降低堆焊层的硬度落差,改善堆焊材料的耐磨性.     

Research on High Speed Machining of TC17 Titanium Alloy Under Extreme Environments

In this paper, high-speed cutting experiment has been carried out on TC17 titanium alloy after secondary ageing treatment in extreme environments, ? 60 and 300 °C respectively. Hyperfocal 3D microscopic system has been adopted to analyze the cutting surface morphology; TEM microstructure analysis has been carried out on TC17 titanium alloy before and after cutting, and the cutting tool’s frictional wear and surface quality have been studied after cutting TC17 titanium alloy in extreme environments. The results show that: the cutting tool mainly displays abrasive wear at ? 60 °C with chipping problems, while at 300 °C the cutting tool mainly displays oxidative wear and adhesive wear; at ? 60 °C, the hardness and brittleness of TC17 titanium alloy increases after subzero treatment, and the cutting produces poor surface quality; at 300 °C, both the hardness and brittleness of the alloy decreases after regressive heat treatment, but the tenacity increases. During the cutting, oxide film is generated on a constant basis, thus the surface quality gets significantly enhanced, and the cutter life lengthened; at ? 60 °C, the dispersed phase of the material gets finer, while at 300 °C, the dispersed phase disappears considerably, or rather, regression takes place.     

14Cr 1Mo 15V高铬白口铸铁的深冷硬化机理

 采用X射线衍射、磁性法和硬度测量等方法研究了深冷处理对高铬白口铸铁显微组织和硬化行为的影响。结果表明，去稳+深冷处理铸铁的硬度比未深冷处理铸铁明显提高，从HRC 641提高到HRC 670。这是因为深冷处理使高铬白口铸铁的残余奥氏体量大大下降，马氏体的大量形成和细微二次碳化物的析出强化作用显著提高了高铬白口铸铁的硬度。深冷处理后铸铁组织中仍存在少量残余奥氏体。     

Mechanical Properties and Corrosion–Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion–abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion–abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion–abrasion wear conditions.     

Friction and wear behaviours of surface densified powder metallurgy Fe–2Cu–0.6C material

Surface rolling was employed to fabricate a densified layer on a powder metallurgy (PM) Fe–2Cu–0.6C piece. A densified surface layer with a depth of 335?μm and a surface hardness of 330?HV_0.1 was obtained, in which the lamellar spacing of pearlite and grain size of ferrite were refined. Friction and wear behaviours of the surface densified material were studied. Results indicated that friction coefficient of the rolled material decreased as the load increased, which was lower than that of the un-rolled material. Wear volumes were lower than that of the un-rolled material, which increased as the load increased. Wear loss was caused by flake spalling and grooves, and the wear mechanism mainly was abrasive wear. The surface densified layer with higher hardness and lower porosity can hinder the cracks initiation and propagation on the surface and under the surface, which enhance the wear resistance of the PM material.     

差温热处理工艺对Cr5钢摩擦磨损性能的影响

 运用扫描电镜观察Cr5钢在不同淬火温度下的显微组织,通过洛氏硬度计和摩擦磨损试验机分析淬火温度对Cr5钢摩擦磨损性能的影响。结果表明：Cr5钢淬火后的基体组织是马氏体,基体上会分布有未溶碳化物。随着淬火温度提升,未溶碳化物逐渐减少,淬火组织逐渐均匀化,但淬火温度达到一定值(1 050～990 ℃)时,碳化物基本溶解完全,组织较均匀,硬度值最大,为54.7HRC,磨损失重量最小,磨损表面相对较平整,耐磨性相对较好;继续升高淬火温度,马氏体组织粗大化,使得硬度有所降低,耐磨性下降。     

粉末烧结Cu-C-SnO2多孔材料摩擦磨损特性研究

铜-石墨复合材料是一种优良的导电耐磨材料,但铜与石墨润湿性很差,导致材料的耐磨性能不足。本文通过向原料中加入与石墨亲和性良好的SnO₂,利用粉末冶金的方法制得Cu-C-SnO₂多孔材料,研究了烧结温度及成分配比对烧结体孔隙率、物理特性及摩擦磨损性能的影响。结果表明：烧结体的孔隙率随烧结温度升高而降低,随石墨/SnO₂质量比增大而增大,随非金属/Cu质量比增大而减小;烧结体的密度、硬度、渗油率等与孔隙率密切相关,随孔隙率升高,密度和硬度呈降低趋势,渗油率呈上升趋势;但试样硬度受Cu₂O产生和Cu颗粒再结晶的影响而变化复杂,在烧结温度830℃附近出现突变。干摩擦条件下,试样摩擦磨损特性受材料硬度和石墨相自润滑作用等多重因素影响而变化复杂,随试样硬度和石墨含量的升高而降低;渗油后试样的摩擦磨损特性则主要受油膜润滑控制,与干摩擦相比,相对摩擦因数和磨损率均显著减小,试样磨损率随渗油率的增大而减小,但在石墨/SnO₂质量比0.155附近存在突变。     

真空热压超高碳超高铬模具钢研究

采用真空热压技术制备了含有超高碳和铬（2.6%C,26%Cr,质量分数）的模具钢。基于差示扫描量热分析曲线,选取两个远低于熔点的温度（1100 ℃和1150 ℃）进行热压,分别制造出几乎完全致密、粉末之间冶金结合良好的块体钢,密度为7.45～7.47 g?cm?3;对应热压温度1100 ℃ 和1150 ℃,热压态钢中平均碳化物尺寸分别为3.5 μm和5.5 μm,最大碳化物尺寸分别为6.0 μm和8.5 μm。经1150 ℃淬火、500 ℃回火,1100 ℃ 和1150 ℃热压钢的平均硬度分别为HRC 62.6和HRC 60.8,平均三点弯曲强度分别为2060 MPa和1850 MPa;经1150 ℃淬火、550 ℃回火,1100 ℃ 和1150 ℃热压钢硬度分别为HRC 55.2和HRC 53.6,平均三点弯曲强度分别为2490 MPa和2320 MPa。在相同淬火和回火条件下,1100 ℃热压钢的三点弯曲强度较高,原因是淬火回火后钢中碳化物尺寸较小。     

石墨形态和铬含量对铸铁干摩擦学性能的影响

使用ＭＭ—２００磨损试验机研究了石墨形态和铬含量对铸铁与石棉基摩擦材料配副时的干摩擦学性能。结果表明,蠕墨铸铁的磨损率最低;摩擦系数由高到低依次为：片墨铸铁、蠕墨铸铁、球墨铸铁。蠕墨铸铁中,随着铬含量的增加,耐磨性能明显提高,摩擦系数略有降低。在高速、高载荷条件下,铬含量的质量分数达到１．５％时,耐磨性可达普通蠕墨铸铁的４倍以上;随着载荷的增加,蠕墨铸铁的摩擦系数降低,磨损率提高。在高速条件下,摩擦系数降低的幅度比在低速条件下小。铬改善蠕墨铸铁干摩擦学性能的效果在高速使用条件下更为突出。     

高铬白口铸铁低速重载条件下的干滑动摩擦磨损特性

研究了不同类型碳化物和不同基体组织的高铬白口铸铁在低速（滑动速度为0.4187～1.0467m/s），重载（接触应力为1～21MPa）条件下与淬火40Cr钢（硬度HRC51～53）配副的干滑动摩擦磨损特性，结果表明，在（Fe,Cr)7C3、（Fe,Cr）3C和（Fe,Cr）33C63种碳化物中，（Fe,Cr）7C3有利于提高高铬白口铸铁的耐磨性，（Fe,Cr）3C有利于降低摩擦系数，共析组织，奥氏体和马氏体3种基体相比，共析组织基体使合金具有较高的摩擦系数，而奥氏体基体合金的耐磨性最好，存在一个临界摩擦应力，当摩擦应力大于此值时，磨损率急剧上升。