高铬抗磨白口铸铁的冶金学

本文论述了碳化物类型、数量、形态以及基体类型如何通过合金元素及热处理工艺的控制,在经济条件下获得最佳耐磨性,介绍了验算高铬铸铁化学成分的设计是否正确的经验公式。     

锰对硼白口铸铁组织与性能的影响

探索了锰对硼白口铸铁组织与性能的影响,以了解锰在硼白口铸铁中的作用。结果表明,含锰4%～5%的硼白口铸铁具有较好的淬透性和淬硬性。     

低铬白口铸铁的组织、性能及其应用

本文研究了低铬白口铸铁的组织和性能及其在水泥磨机中的应用。结果表明：低铬白口铸铁磨球具有硬度高，磨耗低等特点，其使用寿命是普通锻钢球8倍以上。     

电火花表面强化技术的研究现状

对电火花表面强化技术的国内外研究现状进行了比较全面的评述,详细介绍了电火花表面强化设备发展经历的不同阶段和电火花表面强化技术的应用现状,系统分析了电火花强化工艺方法、电火花强化层机械性能方面国内外研究状况、发展趋势和存在的不足之处.     

合金白口铸铁二次硬化研究

本文分析了合金白口铸铁二次硬化的硬度及残余奥氏体随回头温度变化的规律，从而提出通过热处理手段提高合金白口铸铁抗磨性的途径。     

电火花表面强化技术发展概况

对电火花表面强化技术的基本原理、技术特点、发展概况及发展趋势进行了综合评述。     

锻造白口铸铁轧辊缺陷的补焊工艺研究

锻造白口铸铁轧辊使用的是高碳低合金材料DT21,其可塑性低且可焊性差。为减少废品损失,一重集团公司在引进山东工业大学的白口铸铁冷补焊专利技术的同时,继续进行了大量工艺性试验。本文论述了冷补焊、予热补焊及冷热结合补焊3种工艺的模拟试验,并对试验结果进行了理论分析。实践表明,对于低塑性材料轧辊的小缺陷,冷补焊工艺可行;而对于较大缺陷,则宜采用冷热结合的补焊工艺。     

电火花表面强化工艺及其应用

电火花强化工艺是一种简便而灵活的金属表面处理方法，它是通过电火花放电作用将作为电极的导电材料熔渗进工件表层金属，形成合金化的表面强化层，从而使工件表面的物理、化学和机械性能得到改善。目前，电火花表面强化工艺在模具、刀具、机械零件等的强化与修复方面已得到广泛应用。     

电火花表面强化工艺及设备

介绍了电火花表面强化的原理及特点,概述了电火花表面强化设备的现状,最后讨论了电火花表面强化技术的发展趋势。     

离心铸造合金白口铸铁轧辊的研究

应用离心铸造方法,研制CrMoWVNb白口铸铁轧辊。分析合金元素在轧辊中的作用及裂纹产生原因,提出了消 除裂纹措施并应用于高速线材轧机预精轧机架,使用寿命达到高镍铬无限冷硬铸铁轧辊的4～5倍。     

Abrasive wear study of white cast iron with different solidification rates

The abrasive wear resistance of white cast iron was studied. The iron was solidified using two solidification rates of 1.5 and 15 °C/s. Mass loss was evaluated with tests of the type pin on abrasive disc using alumina of different sizes. Two matrices were tested: one predominantly austenitic and the other predominantly martensitic, containing M₃C carbides. Samples with cooling rate of 15 °C/s showed higher hardness and more refined microstructure compared with those solidified at 1.5 °C/s. During the test, the movement of successive abrasives gave rise to the strain hardening of the austenite phase, leading to the attainment of similar levels of surface hardness, which explains why the wear rate showed no difference compared to the austenite samples with different solidification rates. For the austenitic matrix the wear rate seems to depend on the hardness of the worn surface and not on the hardness of the material without deformation. The austenitic samples showed cracking and fracture of M₃C carbides. For the predominantly martensitic matrix, the wear rate was higher at the solidification rate of 1.5 °C/s, for grain size of 66 and 93 μm. Higher abrasive sizes were found to produce greater penetration and strain hardening of austenitic matrices. However, martensitic iron produces more microcutting, increasing the wear rate of the material. The analysis of the worn surface by scanning electron microscopy indicated abrasive wear mechanisms such as: microcutting, microfatigue and microploughing. Yet, for the iron of austenitic matrix, the microploughing mechanism was more severe.     

电火花修复涡轮导向叶片试验研究

研究了电火花修复K418涡轮导向叶片,为涡轮导向叶片的修复提供了理论依据.通过观察试样金相组织及测量显微硬度,并对所得试验数据进行分析,得出结论:修复后试样的金相组织较修复前均匀,晶粒明显细化;修复后试样硬度值一般提高30～50 HV,可以推断试样的耐磨性将会得到改善;最优工艺参数为电压65V,功率B2,频率C1,最大影响因素为电压;修复中还存在气孔、裂纹等缺陷,可以通过进一步试验,比如对试样进行预热、缓冷、改变材料成分等加以避免.     

Sliding wear of graphite crystallized chromium white cast iron

The effects of sliding velocity, heat-treatment and graphite shape on sliding wear of graphite crystallized chromium white cast iron were studied. Two types of graphite crystallized chromium white cast irons having flaky or spheroidal and another type of 2.6C–15Cr white cast iron were prepared for this study. The effect of sliding velocity on wear resistance was studied by the Okoshi type and pin-on-disk type wear tests on materials which have experienced “as cast” and “heat-treated” conditions. The Okoshi type wear test results are divided into two relationships depending on sliding velocity or distance. Two regimes, initial wear and steady-state wear, existed for wear loss and sliding distance. A characteristic form of wear curve with a peak and a minimum was obtained when correlating wear loss and sliding velocity. The wear resistance of graphite crystallized chromium white cast irons were superior to that of 2.6C–15Cr white cast iron. In the results of pin-on-disk tests, there was no clear difference in the reported wear loss and friction coefficient among the alloys. However, an opposite tendency has appeared in the wear loss and friction coefficient: the wear loss value reached a peak in the wear curve at 0.52 m/s, while the friction coefficient reached a minimum at 0.52 m/s.     

浅析高铬白口铸铁磨球的铸态组织设计

在传统工艺的实际生产条件下，高铬白口铸铁磨球易形成较大的内应力，这是导致此类磨球生产和服役条件失效的主要原因。分析热加工全过程可知磨球铸态组织设计的重要性在于期望目标下的铸态组织完全可能仅需采用亚温处理工艺就可达到组织和性能要求，从而不仅从根本上解决了内应力这一中心问题，而且可降低能耗、成本，改善作业环境和缩短生产周期。     

Effect of carbide fraction and matrix microstructure on the wear of cast iron balls tested in a laboratory ball mill

The effect of carbide volume fraction from 13 to 41% on the wear resistance of high chromium cast irons was evaluated by means of ball mill testing. Martensitic, pearlitic and austenitic matrices were evaluated.

The 50-mm diameter balls were tested simultaneously in a 40 cm diameter ball mill. Hematite, phosphate rock and quartz sand were wet ground. The tests were conducted for 200 h.

Quartz sand caused the highest wear rates, ranging from 6.5 to 8.6 μm/h for the martensitic balls, while the wear rates observed for the phosphate rock ranged from 1.4 to 2.9 μm/h.

Increasing the carbide volume fraction resulted in decreased wear rates for the softer abrasives. The almost complete protection of the matrix by carbides in eutectic microstructures caused the eutectic alloy to present the best performance against hematite or phosphate rock. The opposite effect was observed for the quartz sand. The quartz abrasive rapidly wears out the matrix, continuously exposing and breaking carbide branches. A martensitic steel presented the best performance against the quartz abrasive.

With phosphate rock, the wear rate of 30% carbide cast irons increased from 1.46 to 2.84 and to 6.39 μm/h as the matrix changed, respectively, from martensitic to austenitic and to pearlitic. Wear profiles of worn balls showed that non-martensitic balls presented deep subsurface carbide cracking, due to matrix deformation. Similar behavior was observed in the tests with the other abrasives.

In pin-on-disc tests, austenitic samples performed better than the martensitic ones. This result shows that pin tests in the presence of retained austenite can be misleading.     

Solidification and abrasion wear of white cast irons alloyed with 20% carbide forming elements

Three different white cast irons with compositions of Fe–3%C–10%Cr–5%Mo–5%W (alloy no. 1), Fe–3%C–10%V–5%Mo–5%W (alloy no. 2) and Fe–3.5%C–17%Cr–3%V (alloy no. 3) were prepared in order to study their solidification and abrasion wear behaviors. Melts were super-heated to 1873 K in a high frequency induction furnace, and poured at 1823 K into Y-block pepset molds. The solidification sequence of these alloys was investigated. The solidification structures of the specimens were found to consist of austenite dendrite (γ); (γ+M₇C₃) eutectic and (γ+M₆C) eutectic in the alloy no. 1; proeutectic MC; austenite dendrite (γ); (γ+MC) eutectic and (γ+M₂C) eutectic in the alloy no. 2, and proeutectic M₇C₃ and (γ+M₇C₃) eutectic in the alloy no. 3, respectively.

A scratching type abrasion test was carried out in the states of as-cast (AS), homogenized (AH), air-hardened (AHF) and tempered (AHFT) using the abrasive paper with 120 mesh SiC and 10 N application load. In all the specimens, the abrasion wear loss was found to decrease in the order of AH, AS, AHFT and AHF states. Abrasion wear loss was lowest in the specimen no. 2 and highest in the specimen no. 1 except for the as-cast and homogenized states in which the specimen no. 3 showed the highest abrasion wear loss. The lowest abrasion wear loss of the specimen no. 2 could be attributed to the fact that it contained proeutectic MC carbide, eutectic MC and M₂C carbides having extremely high hardness. The matrix of each specimen was fully pearlitic in the as-cast state but it was transformed by heat-treatments to martensite, tempered martensite and austenite. From these results, it becomes clear that MC carbide is a significant phase to improve the abrasion wear resistance of white cast iron.     

球墨铸铁曲轴表面强化处理技术

柴油机曲轴承受复杂交变的弯曲-扭转载荷和一定的冲击载荷,疲劳断裂是曲轴的主要破坏形式,裂纹源易发生在连杆轴颈与曲臂过渡圆角处,工艺上提高曲轴疲劳强度的方法主要是圆角强化,在其表层形成一定的压应力来实现的。介绍了滚压、淬火、氮化、喷丸、激光冲击强化等工艺方法,分析曲轴强化机理和工艺方法,为提高曲轴使用寿命提供了参考。     

钛、硼高铬铸铁的试验及应用

研究Ti和B对高铬铸铁组织和性能的影响表明川和B能使高铬铸铁组织细化,硬度提高,动态断裂韧性提高33％,抗磨性提高。根据装机试验,用这种铸铁铸造的衬板寿命比不加Ti8衬板寿命提高二倍。     

铸铁阀门耐腐蚀性能的分析

阐述了铸铁的腐蚀机理及特点，分析了铸铁与铸钢阀门在海水中的腐蚀速度，介绍了孕育铸铁加合金后抗腐蚀能力及镍铬铸铁工况运行情况。