Si元素对明弧堆焊奥氏体合金组织及耐磨性的影响

为获得以奥氏体为基体且韧性及耐磨性良好的明弧堆焊合金,采用药芯焊丝自保护明弧焊方法制备了以奥氏体为基体的Fe-C-Mn-Cr-Nb-V-Ti系多元耐磨合金,借助X射线衍射仪、扫描电镜及其附属能谱仪等测试手段,研究了Si含量对其组织和耐磨性的影响。结果表明:堆焊合金基体为γ-Fe,硬质相有(Fe,Cr,Mn,V)_(23)C_6,(Nb,Ti)C和(Fe,Cr)_3(C,B)等;当堆焊合金含1.5%Si(质量分数)时,出现了沿晶(Fe,Cr,Mn,V)_7C_3相;随着Si含量提高,沿晶界分布的(Fe,Cr,Mn,V)_(23)C_6型碳化物数量先增加然后减少,形态从树枝骨架状变为层片状离散孤立分布,胞状γ-Fe晶内原位析出的(Nb,Ti,V)C复合碳化物随之增大,堆焊合金耐磨性呈先提高后下降再提高的趋势;0.9%Si和1.5%Si堆焊合金试样的磨损质量损失低于一般高铬铸铁,具有良好的耐磨性和韧性,其磨损机制主要为磨粒的显微切削。     

Fe—C—Cr—V—B系高铬堆焊合金的显微组织及耐磨性

采用药芯焊丝埋弧堆焊方法制备含有C 1 2%～1 8%(质量分数,下同),Cr 15%～20%,V 2 0%～3 0%,B 0%～1 0%的高铬堆焊合金.借助光学显微镜、扫描电镜和X射线衍射等分析手段,研究其显微组织及碳化物分布形貌,结果表明:其显微组织由α-Fe+γ-Fe+(Fe, Cr)7C3+ (Fe, Cr)3C+Fe3(C, B)+B4C等组成,加入B4C可显著细化该堆焊合金晶粒,降低α-Fe,γ-Fe基体组织的Cr,V等合金元素的固溶量,使碳化物(Fe, Cr)7C3数量增加且呈弥散分布.另外,考察了B4C含量对高铬堆焊合金硬度及耐磨性的影响,耐磨粒磨损实验结果表明其相对磨损系数是H25Cr3Mo2MnV堆焊合金的6～17倍,其中碳化物颗粒四周均匀分布的α-Fe等基体组织使其可承受较大的磨粒冲击而不脱落.     

添加Mo对高铬铸铁组织及亚临界处理硬化作用的影响研究

为提升高铬铸铁的综合性能,以无Mo高铬铸铁和含1.0％(质量分数)Mo高铬铸铁为研究对象,对比研究了添加Mo元素对铸态高铬铸铁组织结构以及550℃亚临界处理对其组织及硬度的影响.研究表明:2种铸态高铬铸铁的主要组成相均为奥氏体、马氏体及(Cr,Fe)7C3,但含Mo高铬铸铁中奥氏体含量明显增多.铸态高铬铸铁均以亚共晶方...     

Mo对烧结机台车高铬铸铁篦条磨损性能的影响

为深入了解Mo对烧结机台车高铬铸铁篦条磨损性能的影响,模拟了相关磨损工况,通过磨损试验及扫描电镜等手段对2种不同成分的高铬铸铁篦条的耐磨粒磨损性能和耐冲蚀磨料磨损性能进行了对比研究,并简要探讨了磨损机制.结果 表明:2种试验篦条的组织均主要由奥氏体、马氏体和(Cr,Fe)7C3型碳化物组成,其中含Mo篦条的显微组织较细...     

高铬铸铁中残余奥氏体的X射线衍射定量分析

为了消除高铬铸铁中碳化物对残余奥氏体定量的影响,采用电解方法定量萃取高铬铸铁中的碳化物。经X射线衍射分析,碳化物为（Cr,Fe）7C3。选择碳化物的（411）晶面衍射强度作为标准,测量其它峰的相对衍射强度,得出马氏体与奥氏体（200）晶面的衍射强度校正因子分别为0．12和0．44。校正了碳化物对奥氏体定量分析的影响,可提高测量精度10％以上。     

等离子原位合成Fe-Cr-V-C堆焊合金的耐磨性

采用等离子堆焊技术制备了不同Cr含量的Fe-Cr-V-C堆焊合金,借助扫描电镜和X射线衍射等分析手段研究了碳化物形貌及合金物相组成。同时研究了Cr含量对合金硬度和耐磨性的影响,并探讨了磨损机理。结果表明:堆焊合金组织由马氏体、铁素体、奥氏体、M7C3及VC组成。合金中随着Cr含量的提高,由于硬质相M7C3和VC的数量及形态变化不大,而具有高硬度的针状马氏体基体组织的减少使得合金的耐磨性先降低,当达到一定值后继续增加Cr含量,M7C3的数量逐渐增多,因而耐磨性随后增大;当Cr含量达到27.2%(质量分数)时,大量高硬度六边形M7C3复合物(约HV1200)结合一定量VC(约HV1600)颗粒构成坚实的耐磨骨架,使得合金具有最佳的耐磨性。     

16Cr2Mo1Cu高铬铸铁在亚临界处理中硬化行为研究

研究了亚临界处理对16Cr2Mo1Cu高铬铸铁的组织转变和性能的影响,并利用X射线衍射分析、磁性法和硬度测定法分析了硬化机制.研究表明:16Cr2Mo1Cu高铬铸铁的铸态组织由残余奥氏体、马氏体和M7C3型共晶碳化物组成,其相对含量分别为77.0%,7.2%和15.8%;在亚临界处理过程中,基体组织中的残余奥氏体析出二次碳化物并在冷却过程中转变为马氏体,使该合金在560～600℃的亚临界处理过程中出现二次硬化;在适当的处理温度和保温时间下,16Cr2Mo1Cu高铬铸铁可得到最高的硬度.     

定向凝固高铬白口铸铁干滑动摩擦磨损特性

研究了定向凝固高铬白口铸铁与淬火 40Cr钢 (硬度HRC5 1～ 5 3 )配副时碳化物纤维排列不同位向的干摩擦磨损特性。结果表明 ,碳化物纤维排列不同位向的相对耐磨性随摩擦功率而变化。摩擦功率低于某一临界值时 ,碳化物纤维垂直位向的磨损率较其它位向的低 ;摩擦功率高于该临界值时 ,碳化物纤维垂直位向的磨损率反而高于其它位向的。该临界值的高低与基体组织有关 ,奥氏体基体时最高。摩擦系数与碳化物纤维排列位向无关。     

高铬铸铁耐磨材料在泥沙磨损条件下耐磨性影响因素分析

分析了碳化物形态与分布、基体组织和稀土变质处理对高铬铸铁耐磨材料在泥沙磨损条件下的耐磨性影响。结果表明：碳化物的形态和分布对高铬铸铁的耐磨性有直接影响,块状或短杆状且分布均匀的碳化物对提高材料的耐磨性有利,网状或长针状碳化物对耐磨性不利;在泥沙磨损试验条件下,提高高铬铸铁中基体组织的显微硬度和基体组织与碳化物的结合强度有利于提高高铬铸铁材料的耐磨性;稀土元素的加入,使高铬铸铁的晶粒细化,碳化物颗粒变得细小,分布更为均匀,有利于提高高铬铸铁在泥沙磨损条件下的耐磨性。     

Cr8Nb3CSiMnTi系堆焊合金的组织及耐磨性研究

为解决中铬合金耐磨性不足的问题，采用“复合粉粒+H08A实心焊丝”埋弧焊方法制备Cr8Nb3CSiMnTi系中铬耐磨合金，借助X射线衍射仪(XRD)、扫描电镜(SEM)及附属能谱仪(EDS)等手段，研究了碳含量对该合金组织和耐磨性的影响。结果表明：中铬堆焊合金的基体由α-Fe构成，硬质相包括(Fe, Cr)₇C₃、(Fe, Cr)₃C碳化物和(Nb, Ti)C等相；随着碳含量升高，α-Fe固溶的铬含量持续减小，沿晶(Fe, Cr)₇C₃型碳化物数量增多，形态从孤立状依次改变为树枝状、定向聚集态等，与(Nb, Ti)C相的间距随之减小。湿砂橡胶轮式磨损试验结果显示，随碳含量提高，堆焊合金的耐磨性先显著改善然后降低，这主要与沿晶碳化物(Fe, Cr)₇C₃数量提高以及其与(Nb, Ti)C相的间隔距离改变有关；堆焊合金的韧性则先持续下降，然后上升，这不仅决定于基体数量，而且与沿晶碳化物的形态及其分布有关；其磨损机制包括显微切削和剥落，以显...     

Microstructure and mechanical properties of high boron white cast iron

In this paper, high boron white cast iron, a new kind of wear-resistant white cast iron was developed, and its microstructure and mechanical properties were studied. The results indicate that the high boron white cast iron comprises a dendritic matrix and an interdendritic eutectic boride in as-cast condition. The distribution of eutectic boride with a chemical formula of M₂B (M represents Cr, Fe or Mn) and with a microhardness of HV2010 is much like that of carbide in high chromium white cast iron. The matrix includes martensite and a small amount of pearlite. After quenching in air, the matrix changes to martensite, but the morphology of boride remains almost unchanged. In the course of austenitizing, a secondary precipitation with the size of about 1 μm appears, but when tempered at different temperature, another secondary precipitation with the size of several tens of nanometers is found. Both secondary precipitations, which all forms by means of equilibrium segregation of boron, have a chemical formula of M₂₃(C,B)₆. Compared with high chromium white cast iron, the hardness of high boron white cast iron is almost similar, but the toughness is increased a lot, which attributes to the change of matrix from high carbon martensite in the high chromium white cast iron to low carbon martensite in the high boron white cast iron. Moreover, the high boron white cast iron has a good hardenability.     

粉末烧结法和铸造法制备ZrO2增韧Al2O3陶瓷颗粒增强高铬铸铁基复合材料及其耐磨性能

将粒径为1~2 mm的ZrO₂增韧Al₂O₃陶瓷颗粒(ZTA_p)、高铬合金粉末和黏结剂混合真空烧结制备蜂窝状预制体,再浇注高铬铸铁液制备出ZTA_p增强高铬铸铁基复合材料。采用SEM、EDS、XRD分析复合材料的界面微观结构和物相组成,通过三体磨损试验评价复合材料的耐磨性能。结果表明,烧结高铬铸铁基体在铸造过程中发生重熔,与铸造高铬铸铁基体呈冶金结合,ZTA_p与金属基体界面结合致密,无裂纹、气孔等缺陷。复合材料三体耐磨性能达到高铬铸铁的3倍以上。将该复合材料应用于制备磨辊件,经过5 000 h服役,柱状区和复合区在磨辊半径方向上的磨损量分别为8.2 mm、5.9 mm,预计寿命可达到高铬铸铁磨辊的2倍以上。      

Wear behavior of TiB<Subscript>2</Subscript> inoculated 20Cr–3Mo–4C high chromium white cast irons

FeTi, B₂O₃, Al, and FeW particulates, approximately 40–60 μm in size, were mixed in stoichiometric ratio and sintered at 1,200 °C. The sintered particulates were added as 5 wt% to molten high chromium white cast iron over 50 C-deg above the melting temperature, and stirred at 1,000 rpm. The samples were investigated in three groups: (1) high Cr white cast iron inoculated by the particulates sintered from Al–FeTi–B₂O₃ particulates; (2) high Cr white cast iron inoculated by the sintered particulates derived from Al–FeTi, B₂O₃, and FeW particulates; and (3) specimens of the second group that were subsequently homogenized. The microhardness of ceramic particulates was measured as 2,800–3,400 HV₁₀. The effect of sintered particulate volume fraction on the abrasive wear resistance of the high chromium white cast iron was determined. The wear resistance and hardness of the composites improved significantly as a result of particulate inoculation. The application of the homogenization heat treatment to the inoculated samples produced a microstructure having homogeneously distributed particulates.     

Erosive Wear and Wear Mechanism of in situ TiCp/Fe Composites

1.IntroductionMetal-based composite is a kind of environmental ma-terial that can be reused.It combines the beneficialproperties of the metal matrix,such as ductility,goodthermal and electrical conductivity and high toughness,with those of the reforcement phase[1~3].The latter isusually a ceramic,serving to increase the elastic modu-lus,shear strength and hot strength,fatigue and wearresistance.Its development has been widely studied[4~8].Wear of metal materials causes a tremendous loss of ec…     

无压渗透法制备铸造表面复合材料

提出用无压渗透法制备铸造表面复合材料的新方法。通过预先制备带有孔隙的硼铁合金 预制块, 用普通浇注的方法, 获得以灰铸铁为基的铸造表面复合材料。复合层从化合物层到亚共晶 层的厚度达8 mm , 其组织和硬度由表层向基体呈梯度分布, 表面化合物及过共晶层的耐磨性优于 Cr12 型高铬铸铁。      

Cr、Si、Mn、Cu对中低铬白口铸铁抗磨蚀性能的影响

应用磷酸盐石墨铸型浇注中低铬白口铸铁试样 ,用正交试验对它们的抗腐蚀耐磨性进行了研究。分析表明 :试样有较好的抗腐蚀耐磨性 ,最佳成分配比浇注出的试样的抗腐蚀耐磨性为正火态 2 0 #钢的 3倍 ,充分反映了磷酸盐石墨铸型的激冷能力好 ;中低铬白口铸铁的抗腐蚀耐磨性随着铬含量的增加而升高 ;硅的含量以低于 2 %为佳 ,锰和铜的含量分别以在 2 %～ 3%范围和在 1%～ 2 %范围为佳。     

B4C包覆ZTA颗粒增强铁基复合材料制备与性能

ZTA (ZrO₂增韧Al₂O₃)陶瓷颗粒表面包覆B₄C微粉,将其制备成蜂窝状结构陶瓷预制体。采用传统重力浇注工艺将陶瓷预制体与熔融的高铬铸铁(HCCI)金属溶液进行复合,获得ZTA陶瓷颗粒增强高铬铸铁基复合材料。对复合材料中ZTA陶瓷颗粒增强相与高铬铸铁基体之间的界面及复合材料的耐磨料磨损性能进行了研究。结果表明,ZTA陶瓷颗粒与高铬铸铁界面结合处形成了明显的过渡区域,界面过渡区域的存在提高了陶瓷颗粒与金属基体的结合,从而提升了复合材料的整体稳定性能。同时,三体磨料磨损试验表明该复合材料的耐磨料磨损性能是高铬铸铁的3.5倍左右。     

16Cr-2.5Mn高铬白口铁的亚临界热处理研究

研究了亚临界热处理对16Cr-2．5Mn高铬白口铁组织转变和性能的影响，并利用TEM、SEM、XRD和M200磨损试验机分析了其硬化机制和对耐磨性的影响．研究表明：过饱和奥氏体中固溶的Cr和C在亚临界热处理时会以（Cr，Fe）23C6形式析出，残余奥氏体发生了马氏体相变，使合金产生二次硬化；亚临界热处理中，保温时间过长，将导致（Cr，Fe）23C6向M3C原位转变发生，基体组织发生珠光体转变，导致硬度和耐磨性能不同程度降低；残余奥氏体含量为10％左右时，合金获得最高硬度和最佳耐磨性能．     

Reinforcement of Hadfield steel matrix by oriented high‐chromium cast iron bars

To attain a wear‐resistant material compatible with high hardness and high toughness, Hadfield steel matrix was reinforced by oriented high chromium cast iron bars, through inserting high chromium alloys flux‐cored welding wires into Hadfield steel melt at 1500 ± 10 °C. The obtained composites were investigated by XRD, SEM, micro‐hardness, three‐body abrasion wear and impact toughness testers. The results show that the alloy powders inside the flux‐cored welding wires can be melted by the heat capacity of Hadfield steel melt and in situ solidified into high chromium cast iron bar reinforcements tightly embedded in the matrix. The micro‐hardness of reinforcements of the water‐quenched composite is about four times higher than that of the matrix. The impact toughness of the water‐quenched composite is higher than that of the as‐cast composite and lower than that of Hadfield steel, and its fracture mechanism is very complicated and refers to brittle and ductile mixture fracture mode. The excellent impact toughness and better wear resistance of the water‐quenched composite are attributed to combine fully the advantages and avoid the drawbacks of both Hadfield steel and high chromium cast iron. Additionally, in industrial application, the pulverizer plate produced by this composite, has also better wear resistance compared to the reference Hadfield steel pulverizer plate.