高强度灰铸铁盘型凸轮的生产技术

高强度灰铸铁件盘型凸轮的生产技术可以归纳为：选取适宜的化学成分，并注意各元素之间的合理匹配，即埘（c）3．0％～3．2％，W（Si）1．8％～2．0％，W（Mn）1．1％-1．3％，埘（P）≤0．06％，似（S）≤0．04％，采用合理的熔炼和浇注工艺，盘型凸轮的浇注温度为1320～1350℃，选用新型高效的孕育剂，多次孕育等措施，强化孕育效果，改善铸件的基本组织和石墨形态，采用多元低合金化，提高铸件性能。     

Erosion Behaviour of WC–Co–Cr Thermal Spray Coated Grey Cast Iron under Mining Environment

Hydraulic machinery components made of grey cast iron (FG 260 grade) are preferred for engineering application because of their excellent damping properties. However when such materials are exposed to mining environments they exhibit poor erosion resistance without meeting their estimated life time. In order to enhance the service life of the material of hydraulic components, WC–Co–Cr thermal spray coating was identified. Grey cast iron samples (FG 260 grade) with and without WC–Co–Cr coating were subjected to slurry jet erosion tests by varying the impingent velocity and angle under two different pH levels at 3 and 7 which pertain to the mining environment. XRD characterization was done to identify and confirm the carbide phases present. Surface morphology studies were carried by SEM on both the substrate and coating, which revealed the erosion of grey cast iron surface, due to ploughing mechanism. In the case of WC–Co–Cr coating, at oblique angle of impact, the degradation is by micro cutting of the matrix and ploughing mechanism. At normal impingement, the fluctuating stress creates the cracks, which interlink each other and thereby causing erosion of the material.     

稀土在离心灰铸铁管中的作用

利用光学显微镜和扫描电镜并结合电子探针和化学分析,研究了稀土在离心灰铸铁管中的作用。结果表明,在保证灰口铸铁的先决条件下,普通离心灰铸铁管的组织,尽管可随基本化学成分和铸造条件的不同而变化,但其特征是组织粗大且很不均匀,并有明显的分层现象。加入微量稀土后,无论显微组织和宏观组织都显著趋于细化和均匀化,同时,化学成分的偏析也有明显改善。     

Effect of Pressure on Graphite Morphology and Mechanical Properties of Squeeze Cast Hyper-Eutectic Grey Cast Iron

Squeeze casting is a process in which a high external pressure is applied and maintained on the molten metal during the whole solidification process resulting in the lower porosity, higher solidification rate and improved mechanical properties. In this research, the effects of applied pressure on the morphology of graphite flakes in a squeeze cast hyper-eutectic grey cast iron were investigated. The molten grey cast irons were solidified under atmospheric pressure as well as 25, 50 and 75 MPa externally applied pressures. The results indicated that the pressure increase during solidification decreased the amount of free graphite flakes, reduced the size of pro-eutectic Kish graphite flakes and increased the density of the castings. D-type graphite enclosing austenite dendrites, resembling that expected in hypo-eutectic grey cast iron, was observed near the surfaces of the castings solidified under externally applied pressures. Moreover, some compacted and spheroidal graphite particles were observed in the castings solidified under 50 and 75 MPa pressures. Furthermore, by increasing the squeeze casting pressure from atmospheric pressure to 75 MPa, the hardness, ultimate tensile strength and elongation increased by about 13, 68 and 128%, respectively. The results have been discussed in terms of increased cooling rate, expected change in the phase diagram of the alloy, different atomic structure of the interfaces of graphite and austenite as well as some proposed theories for formation of eutectic cells and spheroidal graphite.     

配副体积比对铸铁干摩擦学特性的影响

金属干摩擦副双方的相对体积比影响摩擦热在干摩擦学系统中的分配,从而影响材料的干摩擦磨损性能,在铸铁／４０Ｃｒ钢摩擦副和铸铁闸瓦的实际装车运行试验中,均发现随着铸铁材料的磨损,其干摩擦磨损性能有不同程度的降低。蠕墨铸铁比灰铸铁具有理钕的干摩擦学稳定性。     

含钒蠕墨铸铁干摩擦学性能

研究了含钒蠕墨铸铁与钢盘对磨时的干摩擦学性能。结果表明，钒的加入降低了蠕墨铣的的磨损量，提高了接触压力和摩擦速度变化时磨损量的稳定性。含钒０．１％和０．３％时，提高了摩擦系数和高接触压力，高摩擦速度下降摩擦系数稳定性。     

基于线性规划算法的磷生铁最优化成分设计

铝电解槽阳极组装用磷生铁在使用过程中需要的特性与其本体材料的物理性能息息相关。运用材料热力学的方法计算出五大元素(C,Si,P,Mn,S)的含量变化对磷生铁电导率和热膨胀系数的影响,并通过线性回归建立电导率和热膨胀系数与五大元素含量和温度的函数关系,最后利用线性规划最优化算法对某铝厂现行磷生铁成分进行有目的性的优化。通过优化后,磷生铁电导率最大优化率为14.50%,热膨胀系数最大优化率为5.99%。     

铈、镧、钕和硫在铸铁中行为的研究

研究了不同含硫量和不同冷却速度下铈、镧和钕对铸铁石墨形态和基体组织的影响。试验表明，不同的稀土元素在铸铁中的行为是不一样的。同时，硫和冷却速度对稀土元素的作用有重要的影响。     

盘式制动器在冶金行车上的应用

长期以来,国内冶金起重机基本上使用鼓式制动器,国内许多钢铁公司新上项目的起重机上使用的盘式制动器。通过具体实例计算分析说明,盘式制动器完全能达到现场的安全要求。     

氮对灰铸铁初生奥氏体析出温度的影响

用差热分析的方法测定了氮对Fe^-C_3.45^-Si_2.15和Fe^-C_3.45^-Si_2.15^-Mn_0.80灰铸铁初生奥氏体析出温度的影响,并运用热力学原理对实验结果进行了讨论。     

氮对灰铸铁初生奥氏体二次枝晶组织的影响

采用单向凝固方法研究了氮对Fe-C-Si和Fe-C-Si-Mn灰铸铁初生奥氏体二次枝晶组织的影响.结果指出,氮使Fe-C-Si-Mn灰铸铁初生奥氏体二次臂间距减小,二次枝晶组织细化.     

铸铁中磷的分布

利用 Auger 表面分析和化学分析等手段,研究了铸铁中磷在铁/石墨界面上的偏析及在铁相与石墨两相间的分配。实验结果表明,磷在球铁中有界面偏析现象,而在灰铁中没有发现偏析。磷在球铁和灰铁中的偏析特点正与硫在这两类铸铁中的偏析特点相反。     

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。     

铸铁机的选择与核算

介绍了威海鑫山铁厂2号高炉铸铁机工艺要求及设备选型、铸铁机功率及生产能力的核算、铸铁机铁水罐倾翻方式的选择等。通过选择与核算,确定最适合的设备与工艺,以降低投资并提高经济效益。     

Ductility Loss in Ductile Cast Iron with Internal Hydrogen

Hydrogen-induced ductility loss in ductile cast iron (DCI) was studied by conducting a series of tensile tests with three different crosshead speeds. By utilizing the thermal desorption spectroscopy and the hydrogen microprint technique, it was found that most of the solute hydrogen was diffusive and mainly segregated at the graphite, graphite/matrix interface zone, and the cementite of pearlite in the matrix. The fracture process of the non-charged specimen was dominated by the ductile dimple fracture, whereas that of the hydrogen-charged specimen became less ductile because of the accompanying interconnecting cracks between the adjacent graphite nodules. Inside the hydrogen-charged specimen, the interspaces generated by the interfacial debonding between graphite and matrix are filled with hydrogen gas in the early stage of the fracture process. In the subsequent fracture process, such a local hydrogen gas atmosphere coupled with a stress-induced diffusion attracts hydrogen to the crack tip, which results in a time-dependent ductility loss.     

Interface Analysis and Hot Deformation Behaviour of a Novel Laminated Composite with High-Cr Cast Iron and Low Carbon Steel Prepared by Hot Compression Bonding

A hot compression bonding process was developed to prepare a novel laminated composite consisting of high-Cr cast iron(HCCI)as the inner layer and low carbon steel(LCS)as the outer layers on a Gleeble 3500 thermomechanical simulator at a temperature of 950 ℃ and a strain rate of 0.001s-1.Interfacial bond quality and hot deformation behaviour of the laminate were studied by microstructural characterisation and mechanical tests.Experimental results show that the metallurgical bond between the constituent metals was achieved under the proposed bonding conditions without discernible defects and the formation of interlayer or intermetallic layer along the interface.The interfacial bond quality is excellent since no deterioration occurred around the interface which was deformed by Vickers indentation and compression test at room temperature with parallel loading to the interface.After well cladding by the LCS,the brittle HCCI can be severely deformed(about 57% of reduction)at high temperature with crack-free.This significant improvement should be attributed to the decrease of crack sensitivity due to stress relief by soft claddings and enhanced flow property of the HCCI by simultaneous deformation with the LCS.     

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。     

Investigation of Mechanical Properties and Dry Sliding Wear Behaviour of Squeeze Cast LM6 Aluminium Alloy Reinforced with Copper Coated Short Steel Fibers

LM6 aluminium alloy with 2.5–10 wt% of copper coated short steel fiber reinforced composites were prepared using squeeze casting process. Microstructure and mechanical properties viz., hardness, tensile strength and ductility were investigated. Dry sliding wear behaviour was tested by considering sliding distance and load. Fracture surface and worn surface were examined using field emission scanning electron microscope (FESEM). Hardness of composites increased with increasing wt% of fiber. Tensile strength of composites increased up to 19% for 5 wt% fiber composites. Further addition of fibers decreased the tensile strength of composites. Ductility of the composites decreased with the addition of fibers into the matrix. Wt% of fibers significantly decreased the weight loss, coefficient of friction and wear rate. Also the cumulative weight loss decreased up to 57% for 10 wt% of composites compared to LM6 aluminium alloy. Fracture surface of composite tensile specimen showed dimple formation and fiber pullout. Worn surface of matrix showed long continuous grooves due to local delamination on the surface. However, worn surface of composites showed fine and smooth grooves due to ploughing rather than local delamination. Copper coated steel fiber reinforcement in LM6 aluminium alloy exhibited better mechanical properties and wear resistance compared to matrix.     

Effect of Thermomechanical Fatigue on Precipitation Microstructure in Two Precipitation-Hardened Cast Aluminum Alloys

Thermal loading induces modifications of the precipitation microstructure of Al–Si–Cu–Mg alloys. This study focuses on the effect of deformation on precipitation microstructure during thermomechanical loadings. Several specimens were thermomechanically cycled while others were exposed to the same thermal cycles without any mechanical loading. The nature and morphological characteristics of the precipitation microstructure of the thermomechanically cycled specimens are compared to those of the thermally aged ones, using transmission electron microscopy (TEM), in order to assess the effect of deformation on the precipitation microstructure and especially on the kinetics of precipitate growth. The absence of any significant effect of superimposed straining during thermal cycling is discussed. Implications for the prevision of yield strength degradation during service operation are briefly presented.