硼对等温淬火球墨铸铁组织及性能的影响

研究了不同硼含量对等温淬火球墨铸铁(ADI)的组织、力学性能及耐磨性能的影响.结果表明:铸态下,随着硼含量的增加,石墨球化效果降低,石墨球径增加,数量减少,碳化物数量增多.经900℃奥氏体化1.5 h,280℃等温淬火2h后,试样组织为石墨球、奥铁体和少量碳化物,硼的主要存在形式为Fe23(CB)6、Fe2B和Fe3B.当硼含量小于0.020％时,随着硼含量的增加,试样的布氏硬度、抗拉强度、耐磨性均增强,伸长率降低.当硼含量为0.020％时,试样布氏硬度可达HBW484,抗拉强度可达1 470MPa,磨损率为1.12 mg/m,伸长率为1％.     

退火工艺对W-20%Cu复合材料组织与性能的影响

研究了不同退火温度及退火时间对W-20%Cu复合材料微观组织、硬度、抗拉强度、导电率、密度的影响。结果表明,W-20%Cu复合材料退火温度为750~950℃,随温度升高,导电率和硬度先升高后降低;800℃与900℃分别退火0.5~6 h,导电率下降,硬度先升高后降低。800℃×0.5 h时的W-20%Cu复合材料的导电率相对较高,为47.32%IACS(国际退火铜标准),900℃×1 h时材料硬度相对较高,为285 HB。     

淬火温度对中锰QP钢组织和性能的影响

采用部分奥氏体化-淬火-配分工艺对中锰钢进行热处理,研究不同淬火温度对微观组织和力学性能的影响。试验结果表明:随着淬火温度的升高,试验钢的伸长率先升高后降低,而抗拉强度却逐渐降低。淬火温度为140 ℃时,试验钢中一次马氏体和新生马氏体的体积分数之和最大,因此抗拉强度最高。淬火温度为180 ℃时,试验钢中残留奥氏体的体积分数最大,伸长率最高,综合力学性能最好,强塑积最高为30 328.2 MPa·%。而淬火温度升到200 ℃时,由于试验钢中残留奥氏体的含量减少以及新生马氏体的硬度降低,其伸长率和抗拉强度均降低。     

时效处理对7022铝合金学性生能和导电率的影响

采用光学显微镜、洛氏硬度仪、万能材料试验机和导电率测试仪等研究了时效处理对7022铝合金力学性能和导电率的影响.结果 表明:经过470℃固溶处理420 min后的合金的显微硬度为71.3 HRB,导电率为28.0％IACS,抗拉强度为525.5 MPa,伸长率为11.25％;时效处理过程中,合金的显微硬度、抗拉强度和导电率随着时效时间的增加呈现先升高后降低的变化趋势,而伸长率则与它们呈相反的变化趋势.150℃时效14 h后合金的硬度和导电率分别为89.5 HRB和31.2 ％IACS,110℃时效10h后抗拉强度达到峰值,为607.85MPa.综合考虑7022合金的导电率与力学性能,其最佳热处理制度为470℃固溶420 min+ 150℃时效14 h,此时合金的硬度值为89.5 HRB,导电率为31.2 ％IACS,抗拉强度为595.73 MPa,合金力学性能和导电率的变化为时效时间和时效温度综合作用的结果.     

SPS制备铜/镀铜石墨复合材料的组织和性能

采用放电等离子烧结(SPS)制备不同镀铜石墨含量的铜/镀铜石墨复合材料。研究了镀铜石墨含量对复合材料微观组织、密度、导电率、孔隙率和显微硬度的影响。结果表明,随着镀铜石墨含量的增加,铜基体的组织变得细小、均匀。复合材料的密度与镀铜石墨含量满足公式ρ=-0.1506wt%+8.894。当镀铜石墨含量由0wt%增大12wt%,复合材料的导电率由96.4%IACS降低至58.0%IACS,孔隙率从0.1%升高至8.8%。少量的镀铜石墨具有细晶强化作用,能提高复合材料的硬度。当镀铜石墨含量超过4 wt%,复合材料的硬度开始下降,当镀铜石墨含量达到一定值时,复合材料的硬度甚至低于纯铜材料的硬度。     

硼含量对高硼中碳合金钢显微组织及力学性能的影响

研究了高硼中碳合金钢中硼含量对其显微组织和力学性能的影响。结果表明,该合金钢的铸态组织由硼化物或硼碳化合物、少量残留奥氏体以及马氏体组成。随着硼含量的增加合金钢组织逐渐向过共晶形态转变,鱼骨状共晶组织数量增加。此外,在碳含量不变的情况下,随着硼含量的增加,材料冲击韧度降低、硬度增大。     

壁厚对蠕墨铸铁组织性能的影响

通过浇注具有不同厚度的阶梯件,研究壁厚对蠕墨铸铁组织和性能的影响。结果表明:壁厚≤10 mm时,随着壁厚的增加,蠕化率和伸长率增加,珠光体含量、抗拉强度和硬度急剧下降;壁厚10 mm时,蠕化率均大于85%,珠光体含量、抗拉强度、伸长率和硬度变化均趋于平缓。     

低碳硅锰钢的Q&P热处理工艺

研究了QP工艺对添加硅和锰的低碳钢组织性能的影响。通过X射线衍射仪、电子背散射衍射技术、拉伸试验等对不同QP工艺参数条件下试验钢的组织和性能进行了测试分析。结果表明,经过QP工艺热处理后,试验钢中形成了一定比例的纳米级的残留奥氏体。随着配分温度的升高,试验钢中残留奥氏体含量升高,抗拉强度降低,伸长率增加。配分温度为450℃时,随着配分时间的增加,试验钢中残留奥氏体含量先增加后降低,在配分时间为20 s时达到最大值,但抗拉强度降低,伸长率呈增加趋势。强塑积在450℃配分20 s时最大,与残留奥氏体含量变化一致。     

硼含量对高硼中碳合金钢铸态组织与力学性能的影响

针对高性能轧辊对材质的需求,设计了一种1.0％＜ω(B)＜3.0％和ωω(c)约为0.45％的高硼中碳合金钢,并研究了硼含量对其铸态组织与力学性能的影响.结果表明:高硼中碳合金钢铸态组织由马氏体、少量残留奥氏体及共晶硼碳化合物或硼化物组成.随着B含量的增加,其组织由亚共晶形态向过共晶形态转变,共晶硬质相体积分数呈指数关系变化,材料硬度不断升高,冲击韧性下降.     

热处理工艺对汽车7A85铝合金组织和性能的影响

以汽车用7A85铝合金为研究对象,研究热处理工艺对7A85铝合金显微组织、显微硬度、电导率和力学性能的影响。结果表明,随终时效温度升高和时间延长,合金的导电率持续增大,而硬度和各项力学性能先增加后减小。合金经120℃×4 h+157℃×8 h时效处理,硬度为203.0 HV,导电率为32.8%IACS,屈服强度达到563 MPa,抗拉强度达到751 MPa,断后伸长率为26.3%。     

以新型硼源制备硼掺杂金刚石膜的性能研究

采用微波等离子体化学气相沉积技术,以氧化硼-乙醇溶液作为硼源,制备不同掺硼浓度的金刚石膜。利用扫描电子显微镜、X射线衍射仪、激光拉曼光谱仪、电化学工作站等研究其表面形貌、晶体结构、薄膜质量和电化学性能。结果表明:随硼元素含量升高,金刚石膜的晶体颗粒尺寸先减小后增大,电势窗口由3.1V降至2.6V,阳极电流密度由0.022 7mA·cm-2降至0.011 9mA·cm-2,但对背景电流及电化学可逆性几乎不影响。      

六方氮化硼的制备方法及在合成立方氮化硼中的应用

对中国生产六方氮化硼(hBN)的厂家的制备方法进行了研究,采用感应耦合等离子发射光谱(ICP)、X射线衍射、激光粒度分析及比表面积测定等方法对不同方法制备的hBN粉末进行了检测分析对比。结果发现,其杂质含量、颗粒形貌、结晶度等性能无明显的差异,均属纯度一般的粗制hBN。合成立方氮化硼(CBN)的试验及生产使用表明,虽然不同方法制备的hBN合成CBN的效果和适用性有差别,但均能满足我国CBN单晶合成的需要,为国产合成CBN提供了基础原材料保证。     

Microstructure of vacuum plasma-sprayed boron carbide

In the present study, boron carbide was deposited on Ti-6%Al-4%V alloy by vacuum plasma spraying. Chemical and phase compositions of the initial starting powder and the as-sprayed deposit were characterized using hot gas extraction, x-ray photoelectron spectroscopy, Raman spectroscopy, x-ray diffraction, and transmission electron microscopy. Mechanical properties of the deposition were assessed by microhardness and nanohardness indentation. The microstructure consisted of equiaxed boron carbide grains, microcrystalline particles, and amorphous carbon regions. The amount of boron oxide and amorphous carbon in the coating was increased compared with the initial powder. The measured microhardness was slightly higher than values reported previously (1033±200 HV). There was significant variation in measured nanohardness (−100 + 39 GPa) from point to point caused by multiple phases, splat boundaries, and porosity in the deposited structure. Carbon segregation to grain boundaries and/or splat boundaries in boron carbide was observed directly using spatially resolved electron energy loss spectroscopy method.     

Development of boron white cast iron

Abstract

With boron substituting for carbon in cast iron composition and eutectic borides substituting for eutectic carbides in microstructure as the hard wear resistant phase, a new kind of wear resistant white cast iron has been developed. The microstructure and mechanical properties of this new white cast iron both in the as cast state and after appropriate heat treatments were studied. The results show that the as cast microstructure of the boron white cast iron comprises a dendritic matrix and interdendritic eutectics, and the eutectic compound is that of M₂B or M′_0˙9Cr_1˙1B_0˙9 type, where M represents Fe, Cr or Mn and M′ represents Fe or Mn. The morphology of the eutectic borides is much like that of carbide in high chromium white cast iron, but the hardness of boride is higher than that of carbide. The matrix in as cast microstructure comprises martensite and pearlite. After austenitising and quenching, the matrix mostly changes to lath type martensite and the eutectic borides remain unchanged. In addition, two different sizes of particles, with different forming processes during heat treatment, appear in the matrix. The boron white cast iron possesses higher hardness and toughness than conventional white cast iron and nickel hard white cast iron, and has a better balance between hardness and toughness than high chromium white cast iron.     

六方氮化硼直接转化合成多晶立方氮化硼的研究

以六方氮化硼为初始材料,采用直接转化法在9～15 GPa、1 500～2 100 ℃的条件下合成多晶立方氮化硼。采用X射线衍射仪、扫描电子显微镜、维氏硬度计,对多晶立方氮化硼块材的微观结构和力学性能进行表征。结果表明:在合适的温度、压力条件下,六方氮化硼可转化为纯相多晶立方氮化硼,其晶粒尺寸最小约为70 nm ,最大可达10 μm以上;在温度相同条件下,多晶立方氮化硼块材的晶粒尺寸随着合成压力的升高而减小,硬度随着合成压力的升高而增大,最高硬度可达64.45 GPa。      

Calculation of the hardenability of boron steels

Boron is a chemical element that affects astrongly the hardenability of structural steel The property of boron to increase hardenability has led to the creation of numerous boron-containing steels. At present, the main difficulties in their production have been overcome and the necessary experimental material for calculating the mechanical properties, including hardenability, has been accumulated. The standard J-406SAE describing a method for calculating the hardenability of boron steels has been issued in the U. S. The present work concerns the possibility of applying the method to domestic steels.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 19–22, March 1995.     

Hardening of heat-resisting austenitic steel with boron

Conclusion For increasing the heat resistance of Fe-Cr-Ni alloys the addition of boron is expedient only in the case of alloys in which the strength of the grain boundaries is substantially below that of the body of the grains and in which boron can form an independent phase.TsNIITMASh. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No.1, pp.19–22, January, 1967.