金属型铸造高铬铸铁Cr20组织及性能的研究

研究了金属型铸造高铬铸铁Cr20的铸态组织和性能,以及主要合金元素对性能的影响。结果表明,用金属型铸造的高铬铸铁Cr20的铸态组织为奥氏体基体,共晶碳化物为孤立的块状分布,具有较高的硬度和一定的韧性,并且还可以降低合金元素Mo和Ni的加入量。对于不能通过常规热处理进行淬火硬化的高铬铸铁件,可用金属型铸造来满足在铸态下使用的要求。     

离心铸造复合辊套用高铬铸铁的组织及性能研究

根据复合辊套的生产和使用要求,研究了3种成分的高铬铸铁通过金属型铸造后的组织和性能。结果表明,金属型铸造的Cr20高铬铸铁其铸态组织由枝晶奥氏体、共晶奥氏体和共晶碳化物组成;具有较好的韧性,并且有一定的耐蚀性和良好的耐磨性;铸态硬度达到HRC55左右。Cr20高铬铸铁能满足轧辊的生产和湿摩擦条件下的使用要求。     

孕育与变质处理对高Ni-Cr铸铁的影响

研究了75SiFe孕育和REMg变质对金属型铸造高Ni-Cr铸铁铸态和回火态的组织与硬度的影响。结果表明,75SiFe孕育处理使石墨析出数量增多,增加了奥氏体+石墨的共晶体数量,石墨片长度增加,而板条状碳化物数量减少。REMg变质促进点球状石墨析出,石墨析出数量减少,碳化物转变为断网分布,即呈岛状和骨骼状,高冷却速度弱化REMg的变质作用。75SiFe孕育回火处理促进奥氏体分解,回火后残余奥氏体较多。75SiFe孕育降低高Ni-Cr铸铁的铸态和回火态硬度,而REMg变质可略提高高Ni-Cr铸铁的铸态和回火态硬度。     

含钨量对铸态290Cr26MoW耐磨铸铁组织和硬度的影响

铸态合金耐磨铸铁适用于大型或复杂结构耐磨件。通过金相组织观察、X射线衍射相结构分析、图像分析仪定量金相测试和力学性能检测,研究了含钨量对铸态290Cr26MoW耐磨铸铁组织、结构和硬度的影响规律。结果表明,在含0～2.79%W的范围内,随着含W量的增加,铸态290Cr26MoW耐磨白口铸铁的初生基体数量减少,共晶团数量增加,共晶碳化物数量增加;铸态290Cr26MoW耐磨白口铸铁的碳化物结构类型没有改变,M7C3型碳化物为共晶碳化物;铸态290Cr26MoW耐磨白口铸铁基体的奥氏体比例增加,马氏体减少。马氏体多位于共晶团,即共晶碳化物周围。铸态290Cr26MoW耐磨白口铸铁的硬度由共晶碳化物数量和硬度以及基体中奥氏体和马氏体数量比共同决定。     

热处理工艺对离心铸造高铬铸铁轧辊组织及硬度的影响

采用了光学显微镜、扫描电镜、X射线衍射仪、洛氏硬度计等仪器,研究了离心铸造高铬铸铁轧辊铸态及淬火与回火后的显微组织结构、碳化物和硬度等。结果表明:高铬铸铁轧铸态组织主要是由奥氏体+少量马氏体+(Cr,Fe)₇C₃碳化物组成,碳化物呈粗大板条状或块状,不同温度热处理后,得到回火马氏体+(Cr,Fe)₇C₃+Cr₇C₃碳化物的组织,组织中粗大板条状碳化物消失,得到细小块状或椭圆状碳化物。该高铬铸铁轧辊铸态硬度为56.0HRC左右,在950℃淬火及400℃回火处理后硬度增加到了约65.5HRC。     

热处理对CrO2低铬铸铁组织和性能的影响

研究了ＣｒＯ２低铬铸铁的铸态组织结构，结果指出，铸态组织为Ｆｅ３Ｃ、Ｃｒ７Ｃ３型共晶碳化物＋索氏体基体组成。热处理不改变碳化物类型，但适当热处理可获得较高的硬度。     

铬锰铜合金白口铸铁抗冲蚀磨损性能研究

以铸态铬锰铜合金白口铸铁为对比材料,考察了热处理后的铬锰铜合金白口铸铁的抗冲蚀磨损性能,并对试验材料的冲击断口形貌、抗冲蚀磨损失效机理和冲蚀磨损横切面的金相组织进行了分析。结果表明,在相同的冲蚀条件下,热处理后的两种铬锰铜合金白口铸铁的抗冲蚀磨损性能分别是铸态的1.14倍和1.35倍;这是因为前两者的硬质相碳化物的硬度高于后者组织中的碳化物,发挥了优越的抗磨削作用,同时保护了基体。基体中弥散分布着二次碳化物及具有良好弹塑性的残余奥氏体,也减缓了砂粒冲刷表面时的材料流失;试验材料的冲击断口形貌和冲蚀磨损形貌上也有明显的区别。     

亚临界热处理对复合管高铬铸铁层组织及性能的影响

针对铸态304不锈钢-过共晶高铬铸铁复合管高铬铸铁层硬度不足的问题,采用亚临界热处理来改变复合管过共晶高铬铸铁内层组织及性能。结果表明:亚临界热处理可以有效提升复合管高铬铸铁层硬度,复合管高铬铸铁层的宏观硬度随亚临界热处理温度的升高及保温时间的延长先增加后降低;其中530℃×5 h保温空冷的亚临界热处理使得复合管高铬铸铁层硬度提高最显著,提高了3 HRC左右。复合管高铬铸铁层的室温铸态组织为马氏体、奥氏体、M3C型和M7C3型碳化物;经过亚临界热处理后,析出弥散的M23C6型二次碳化物,降低了奥氏体中含碳量,提高了Ms点,促使奥氏体向马氏体转变。     

热处理工艺对Cr26型高铬铸铁组织和性能的影响

研究了热处理工艺对Cr26型高铬铸铁显微组织和力学性能的影响。结果表明:高铬铸铁铸态组织是由珠光体+奥氏体+马氏体+碳化物组成。热处理促使奥氏体向马氏体转变,热处理后组织主要为马氏体+碳化物。在热处理温度范围内,显著提高高铬铸铁的硬度和冲击韧度,同时均随淬火温度增加而增高,在950℃达到最大值,分别为HRC62.2和8.3 J·cm~(-2)。     

离心铸造气门座圈用高铬铸铁的组织及性能研究

根据气门座圈的生产和使用要求,研究了一种成分的离心铸造高铬铸铁铸态和回火态的组织和性能。结果表明,离心铸造的高铬铸铁其铸态组织由初生奥氏体、共晶奥氏体和共晶碳化物组成,回火态组织由回火马氏体、残余奥氏体和共晶碳化物组成;热处理后的高铬铸铁消除了内应力,减小了晶格畸变,具有较好的强度,并且有一定的硬度。离心铸造高铬铸铁气门座圈能满足大功率内燃机的使用要求。     

不同热处理条件下亚共晶高铬铸铁的组织和性能

利用光学显微镜、扫描电镜、X射线能谱仪以及力学性能测试等方法,对不同热处理条件下的亚共晶高铬铸铁进行微观结构表征以及性能测试,研究不同热处理条件对亚共晶高铬铸铁组织及性能的影响。亚共晶高铬铸铁的硬度和冲击吸收能量随淬火温度的升高和保温时间的延长先升高后下降,淬火回火后的最大硬度可达到58 HRC,最大冲击吸收能量可达到15 J。     

镍硬铸铁的硬化原则及影响因素

讨论了化学成分、热处理方法以及铸造方法对镍硬铸铁硬度的影响规律;介绍了镍硬铸铁件化学成分设计的原则、适宜的铸造方法和镍硬1型铸铁的代用材料;认为低温热处理能有效改善因成分设计不合理造成的铸件硬度较低的状况,变质处理可以提高镍硬铸铁的冲击韧度。     

高硅合金耐热铸铁生产球墨铸铁模具的研制

对铸铁模具使用工况进行了分析,采用了高硅合金耐热铸铁为生产球墨铸铁模具的材质,并介绍了高硅合金耐热球墨铸铁模具的消失模铸造工艺、冶炼工艺、热处理工艺以及该材质模具的实际使用效果。实际生产表明：高硅合金耐热球墨铸铁具有优越的综合耐热疲劳性能,大大提高了模具寿命。     

Effects of RE,V, Ti and B composite modification on the microstructure and properties of high chromium cast iron containing 3% molybdenum

The effects of RE, V, Ti and B on the microstructure and properties of high chromium cast iron containing 3% molybdenum under as-cast and heat treatment conditions were investigated with the method of comparing experiments. The results show that with the increase of RE content, the primary austenite of high chromium cast iron is obviously refined. The morphology of carbide is changed from netlike and lath to small multiangular isolated blocks or massive blocks, the isolated degree of carbide is improved obviously, and the size is significantly refined. The addition of V and B into high chromium cast iron can refine the microstructure, reduce coarse columnar crystals and make the carbide smaller and uniform. Through composite modification with RE, V, Ti and B, the hardness, wear resistance and impact toughness of high chromium cast iron are increased conspicuously. After heat treatment, the hardness of high chromium iron is increased significantly, but the toughness and wear resistance do not show great improvement.     

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.     

热处理对15%热变形低铬耐磨铸铁冲击韧度的影响

采用金相显微镜﹑扫描电镜和冲击试验研究了热处理对经970℃15%热变形的低铬耐磨铸铁冲击韧度的影响。结果表明,15%热变形低铬耐磨铸铁经970℃保温3 h正火后,可获得较高的冲击韧度,但其硬度变化不大。     

Mechanical characteristics of spheroidal graphite cast irons containing Ni and Mn with mixed ferrite and bainitic ferrite microstructure

Abstract

This study aims to clarify the influence of additive elements of Ni and Mn on tensile and impact properties of three kinds of spheroidal graphite cast irons (SG irons), which are as cast, annealed and austempered samples. Spheroidal graphite cast irons with Ni (0–4˙5 mass-%) and Mn (0–0˙5 mass-%) melted by a high frequency induction furnace and cast into a Y block CO₂ mould with 30 mm in thickness. From the viewpoint of heat treatment, tensile strength and hardness of SG irons become larger in the order of ferritised<as cast<austempered ones. Matrix structures of SG irons, which are conducted to austempering treatment from α and γ mixture range, consists of bainitic ferrite with high toughness. Austempered SG iron with 3%Ni in 0˙1%Mn series is found to become higher tensile strength compound with elongation and toughness of 901 MPa, 17% and 915 kJ m^?2.     

离心铸造高铬合金铸铁气门座圈的组织及耐磨性能研究

采用离心铸造制备两种高铬合金铸铁气门座圈.利用X射线衍射仪(XRD)、金相显微镜、洛氏硬度计和扫描电镜(SEM),对气门座圈铸态及热处理态后的试样物相组成、金相组织、力学性能及拉伸断口形貌进行了观察和分析,同时在销盘式摩擦磨损试验机上对高铬合金铸铁气门座圈的耐磨性能进行了磨损试验.结果表明,热处理前高铬合金铸铁主要为由...     

钨对淬火回火高铬铸铁冲击性能和耐磨性的影响

通过冲击试验和磨损试验,研究了钨含量对淬火回火高铬铸铁性能的影响。结果表明,热处理对钨元素的分布影响不大,钨在基体和碳化物中均匀分布。随钨含量增加,淬火回火高铬铸铁硬度增加,冲击韧度和耐磨性先升高后降低。高铬钨铸铁硬度为62～65 HRC,冲击韧度为6～8 J/cm2,一定量钨的加入能显著提高高铬铸铁的耐磨性。