特大型汽车制动鼓的铸造

汽车制动鼓属汽车零件中的安全、易损件。各种类型汽车制动鼓的铸件结构大同小异 ,中小型汽车制动鼓 ,材质为HT2 0 0或HT2 5 0。我厂生产的特大型汽车制动鼓铸件质量为32 0kg。材料标准要求相当于GB94 39- 88的HT30 0 ,抗拉强度≥ 2 76MPa。同时要达到美国机动车辆灰铸铁件标准 (ANSI/ASTM 15 9- 83) ,按牌号G35 0 0C要求 ,抗拉强度≥ 2 4 5MPa ,硬度HB2 0 7～2 5 5 ,含碳量≥ 3.5 % ,显微组织为A型石墨 3～ 5级 ,基体为珠光体 +铁素体或碳化物≤ 5 %。要求化学成分w为 :≥ 3.5 %C ;1.3%～ 1.8%Si;0 .6 %～ 0 .9%Mn ;0 .12 %S ;…     

提高汽车制动耐磨性的研究

通过分析汽车提速后制动鼓耐磨性下降的原因，选用成分ω（％）为：３．２￣３．３℃，１．９￣２．１Ｓｉ，０．８￣１．０Ｍｎ，０．３￣０．４Ｃｒ，０．４￣０．６Ｃｕ的合金材质制作汽车制动鼓以提高其耐磨性的，改进后的汽车制动鼓组织中珠光体量〉９５％，硬度为２００￣２２０，耐磨性良好。     

重型车长寿命制动鼓的开发

对重型车制动鼓开裂问题进行了分析,研究表明:(1)重型车制动鼓产生开裂的原因是制动鼓工作温度高,摩擦部位截面存在大的热应力,以及制动鼓材料导热性不足;(2)铸件材料牌号达到HT250并且铸件本体强度190～230 N/mm2,制动鼓强度已足够,使用中不会因为制动鼓强度不足产生开裂问题。试验表明:HT250制动鼓的w(C)量从3.30%提高到3.40%～3.70%,适当加入合金元素,大大改善了制动鼓的抗热裂能力,提高了制动效能,解决了重型车制动鼓使用过程出现的开裂、摩擦面硬斑等失效问题,提高了汽车的安全性。     

汽车制动鼓Cr灰铁铸件的生产实践

介绍了用0．2％—0．4％Cr灰铁代替HT200生产汽车制动鼓的生产技术，分析了铁液化学成份和生产要点。该方法提高了铸件的强度、硬度、耐磨性和切削加工性能，铸造性能也得到改善。实践表明，该生产方法大大降低了废品率，经济效益显著。     

特大型汽车制动鼓的铸造工艺

各种类型汽车制动鼓的铸件结构大同小异 ,材质一般为 HT2 0 0或 HT2 5 0 ,其常见的铸造工艺如图 1所示 ,即根部朝上 ,凸缘朝下 ,两箱手工或机器造型 ,湿型 ,“自来型芯”。　　我厂为某重型汽车有 图 1　制动鼓常见工艺简图限责任公司配套生产的特大型汽车制动鼓铸件 (图2 ) ,重约 32 0 kg,材质为 HT30 0。特大型制动鼓因根部受剪切 ,且扭矩极大 ,根部极易断裂 ,俗称“刷圈”。为确保根部内在质量 ,我们采取了根部朝下 ,一反常态的浇注工艺 ,经反复试制和改进 ,取得了良好效果 ,成批地生产出符合该公司的 EEMS110 12标准要求的特大型制…     

制动鼓内部缩松缺陷的探讨

1 制动鼓的传统工艺 材质为HT250普通灰铸铁,铸件高220 mm,在凝固过程中,因析出石墨而伴随相变膨胀,有很强的自补能力.在制动鼓浇注系统布置中,采取环形横浇道,3个扁平内浇道的方式,如图1. 国外制动鼓虽然材质牌号仍为HT250,但高度约270 mm,重约为70 kg,且结构与国内制动鼓相比有较大的不同.使用传统工艺后,制动鼓法兰盘及加强带处出现缩松缺陷,如图2和图3所示.     

重型卡车铸铁制动鼓开裂失效行为的机理研究

制动装置对于车辆的安全行驶起着至关重要的作用。目前,载重货车所采用的制动装置主要为灰铸铁制动鼓,当汽车在山路或坡道连续刹车行驶时,制动鼓通常会出现裂纹,影响制动效果,甚至引发交通事故。本文以某铸造公司生产的HT250制动鼓为研究对象,对未服役和服役失效制动鼓试样的微观组织和显微硬度进行了分析和比较。结果表明,制动鼓失效后工作面的石墨片变得粗大,且石墨与珠光体界面出现裂纹,石墨片部分有灰色相生成,而侧面的组织无明显变化。此外,失效制动鼓的硬度有所提高。灰铸铁制动鼓开裂失效行机理主要为经多次冷热循环后,石墨与基体间产生微裂纹,经扩展后导致制动鼓开裂失效。     

汽车制动鼓的失效分析

随着汽车载重和速度的增加,使得所需要的制动鼓材料应当发展同时具有高强度、高抗热疲劳性和良好的硬度.通过对失效的江淮某汽车制动鼓取样分析,其失效原因:①材料强度、硬度过低,制动鼓出现磨痕台阶和轴向裂纹;②在制动时发生组织转变,进一步促使网状裂纹的产生.     

铸元素在汽车刹车盘铸造生产中的应用

<正>汽车制动系统是汽车重要的安全系统,刹车盘、刹车鼓是该系统中关键的保安零件,是汽车零部件中适合大批量砂型铸造的铸铁件之一。山东烟台、龙口、莱州3个地区是中国汽车刹车盘、刹车鼓的生产基地,出口量和国内外主机厂配套量均占全国总产量的90%以上。铸元素自投放市场以来,上述3个地区先后有10家企业,4 5条造型线使用铸元素替代煤粉和膨润土生产刹车盘、刹车鼓铸件,取得令人满意的效果。     

金属型铸造磨球

热电车间球磨机用 73mm磨球 ,力学性能要求 :HRC≥45 ,冲击韧度αK≥ 3J/cm2 。1　生产条件熔炼设备为 50 0kg中频无芯感应炉 ,采用芜湖钢铁总厂生产的普通新生铁 ,铁液出炉温度为 1 4 2 0～1 4 4 0℃ ,铸型采用金属模。2　化学成分(1 )含碳量　含碳量高 ,虽然磨球硬度高 ,但冲击韧度下降 ,易发生脆裂 ,取碳w为 2 .8%～3 .2 %。(2 )含锰量、含磷量　锰能强烈增加碳化物的稳定性 ,能提高强度和硬度 ,但却降低了磨球的塑性和冲击韧性 ,故选锰w为 0 .6 %～ 0 .8% ;磷能提高硬度 ,改善耐磨性 ,但却强烈降低冲击韧性 ,故取P<0 .0 5%。(3)含铬…     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.