Strengthening technology and mechanism for semi-solid die casting of aluminum alloy

Combined with theoretical evaluation,an optimized strengthening process for the semi-solid die castings of A356 aluminum alloy was obtained by studying the mechanical properties of castings solution treated and aged under different conditions in detail,then,the semi-solid die castings and liquid die castings were heat treated with the optimized process.The results show that the mechanical properties of semi-solid die castings of aluminum alloy are superior to those of the liquid die castings,especially the strengthening degree of heat treated semi-solid die castingsis much greater than that of liquid die castings with the tensile strength more than 330 MPa and the elongation more than 10％,and this is mainly contributed to the non-dendritic and more compact microstructure of semi-solid die castings.The strengthening mechanism of heat treatment for the semi-solid die castings of A356 aluminum alloy is due to the dispersive precipitation of the second phase(Mg2 Si) and formation of GP Zone.     

Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe3O4 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer),respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.     

粉煤灰填充尼龙6浇铸制品的研究

将粉煤灰用硅烷偶联剂处理后填充到尼龙6浇铸制品(MC尼龙)中,可以改善制品的吸水性、收缩率及热稳定性等,还可以降低成本。该项研究结果有很大的实用价值。     

基于BP网络的保护渣性能预测模型的研究

结合BP网络计算机实验研究 ,建立了保护渣化学组成与性能的预测模型 ,并利用化学组成与性能的关系 ,对网络的实用性进行了检验 ,结果符合保护渣化学组成与性能的关系。保护渣粘度随着保护渣碱度的增大而减小 ,而半球点温度随碱度增大而增大 ;保护渣的半球点温度和粘度都随着渣中CaF2 含量的增加而减小。用BP网络的误差反向传播算法建立的保护渣的化学组成与性能的预测模型 ,得出的预测值与实际值的误差小 ,对保护渣的设计与应用都有一定的指导作用。     

GCr15轴承钢连铸过程中热物性参数的研究

借鉴前人实验数据,采用一定的数学方法,对轴承钢的热物性参数进行了研究.结果表明：GCr15轴承钢的液相线温度为1 465.7℃,固相线温度为1 328.4℃,零强度温度为1 380℃左右,零塑性温度为1 330℃左右;在固相区、液固两相区、液相区分别采用不同的公式进行处理,可使结果更加准确,还避免了奇异性.研究结果可为轴承钢连铸工艺有限元模拟提供基础.     

CJ91胶粘剂在螺旋振动光整机中的应用

螺旋振动光整机槽内壁的橡皮保护层由于老化及磨损等原因出现裂口甚至脱落现象，严重影响设备的使用寿命和闸把壳体的外观质量。通过分析和试验筛选出螺旋振动光整机的理想胶粘荆——CJ91胶粘剂并介绍了粘接修补工艺。     

离心铸造高速钢轧辊铸造缺陷形成与控制技术研究

采用离心铸造方法制造高速钢轧辊工艺简单,操作方便,但易出现偏析、裂纹、气孔、缩孔及夹杂等缺陷,影响轧辊的力学性能和使用性能.采用稀土-钛复合变质处理改善合金的组织和性能,同时改进离心铸造工艺参数可以消除高速钢轧辊铸造缺陷,提高力学性能,改善使用效果.     

易溃散覆膜砂的应用及发展前景

介绍了覆膜砂用于轻合金铸件生产时溃散性差的原因和提出了改善的办法,并介绍了其发展前景.     

离心铸造CrMoWVNb白口铸铁轧辊的研究

应用离心铸造方法：以Cr,Mo,V,Nb为主要合金元素，研制成功了CrMoWVNb白口铸铁轧辊，分析了合金元素在轧辊中的作用，指出在轧辊中加入适量稀土和钛可细化轧辊组织，改善轧辊性能，同时还分析了轧辊生产中裂纹产生的原因，提出了消除裂纹的措施，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铁轧辊的4－5倍。