铸铁型材在机械制造业中的应用及前景

扼要地阐述了国内外铸铁型材的发展状况。结合目前我国机械制造业及金属加工业使用铸铁型材的需要，对水平连铸铸铁型材的组织及性能特点进行了分析讨论。指出我国铸铁型材的生产及推广使用前景     

7A04-T6铝合金挤压型材热处理

对7A04-T6合金型材热处理制度进行深入研究,制定出合理的工艺制度,使其生产出的T6状态型材的各项性能均能达到指标要求。     

MB2镁合金型材表面黑裂口的本质

MB2镁合金型材用途广,质量要求严格。在生产检验中常发现型材表面有黑裂口,它影响产品的质量和性能。采用宏观检查、光学显微镜及电子探针方法判定MB2镁合金型材表面黑裂口是氧化夹杂所致。     

7B04-T6铝合金挤压型材热处理

对7B04-T6合金型材热处理制度进行深入研究,制定出合理的工艺制度,使其生产出的T6状态型材的各项性能均能达到指标要求.     

铸锭质量对铝型材氧化着色质量的影响

铝铸锭质量对型材的挤压性能、力学性能和表面氧化着色性能起着重要影响,是生产优质型材的基础。论述了在建筑用铝合金熔铸、均匀化等过程中,除渣、除气、细化晶粒、减少偏析、消除内应力与型材表面质量的关系。指出加入细化剂和稀土元素对改善铸锭质量有重要作用。     

低成本钛-铜金属复合型材的热挤压成形

采用无压余热挤压法制备钛-铜金属复合型材,对扁形棒进行拉剪强度检测,观察结合层的组织形貌及拉剪断口形貌等.结果表明:利用回收的钛、采用无压余热挤压法可以生产钛-铜金属复合型材,制备的型材性能稳定,生产工艺可行;该方法可以提高生产效率,降低原材料成本.     

高速列车车体用A6N01铝合金超宽空心型材的研制

介绍了高速列车车体用A6N01铝合金超宽空心型材的研制、生产过程。着重介绍了生产500 km/h高速列车车体用铝合金型材所需要的主辅设备、检测装置、模具设计制造技术,以及先进的熔铸、挤压工艺技术的要求。所生产的铝合金型材的组织、性能全面达到了国际先进水平。     

挤压铝合金及其挤压特性(4)

三、铝型材挤压大部分铝合金型材都是用热处理可强化的合金(6063、6061及 Al-Zn-Mg 合金)挤压的。这些合金除了有很好的挤压性能外,还有适当的机械性能与良好的表面装饰性能及抗蚀性,使得铝合金型材具有压倒其他挤压材料的优势,在国民经济各部门获得了广泛的应用。关于型材生产的难易程度,在德国把型材分为13类,A 类最易挤压,N 类最难(图26)。国际上通用型材外接圆直径描述其大小,外接     

优化6082铝合金型材生产工艺的试验研究

6082铝合金在挤压过程中,挤压力大,型材表面有时会吸附颗粒物,并伴有划伤,使生产效率和成品率降低,型材性能低不能满足技术要求。通过分析型材缺陷产生的原因,严格控制合金的硅、镁、锰含量,适当提高熔铸温度,对铸锭采用高温均匀化和均匀化处理快速冷却等优化生产工艺的措施,使铸锭挤压时的挤压力降低10%,型材的力学性能提高,生产出了表面光亮的优质型材。     

细化剂对2026铝合金组织与性能的影响

研究了Al-5Ti-1B和Al-3Ti-0.15C两种细化剂对2026铝合金铸锭组织、型材组织及型材性能的影响。结果表明,在0.2%的添加量下,Al-5Ti-1B细化剂的细化效果优于Al-3Ti-0.15C细化剂,采用Al-5Ti-1B细化剂生产的铸锭和型材的晶粒尺寸均小于对比试样;采用Al-5Ti-1B细化剂生产的型材强度略高于采用Al-3Ti-0.15C细化剂生产的型材,但伸长率略有降低。     

连铸坯壳表面温度回温机制及影响因素

连铸过程中,坯壳表面回温的发生机制主要有两种。一种是由于二冷区换热方式的差异性;另一种是由于放热强度和换热强度的差异性。拉坯速度、冷却强度及冷却段长度均对坯壳回温有着重要的影响。其中拉坯速度及冷却强度的影响可通过二冷优化配水来减缓,而冷却段长度的影响需要在设计之初优化连铸机二冷区设计的合理性。     

Effects of continuous cast section size on torsion deformation and fatigue of induction hardened 1050 steel shafts

This study investigates the influence of continuous cast section size on the mechanical performance of induction hardened parts produced from steel bars. SAE 1050 steel from commercially produced Jumbo Blooms, Blooms, Rotary Round, and Billet were hot rolled into round bars with diameters of 37-44 mm. These bars were then normalized, machined into test specimens, the gauge sections were polished, and the specimens were case-hardened by induction hardening. Torsional monotonic and fully reversed cyclic fatigue tests were conducted to study the effect of the initial continuous cast section size on deformation and fatigue behaviors. Reduction ratios in this study ranged from a low of 20.4:1 for the Billet, up to a high of 142:1 for the Jumbo Bloom. Test results indicate that the continuous cast section size has only small effects on the torsion monotonic and cyclic deformation properties and negligible effect on the torsion fatigue performance. Small differences observed in deformation and fatigue properties between the four processes are attributed mostly to the variation in case and core hardness levels caused by small differences in chemistry, particularly carbon content. Variations in sulfur content also influence ductility and fatigue behavior. At high strains, the cracks initiated in shear as longitudinal cracks for all four materials. At low strains, the cracks initiated at the surface in tension as spiral cracks due to normal tensile stresses.     

中型轧机轧制偏大型材的生产实践

针对中型轧机轧制偏大型材受设备能力、轧辊强度及坯料尺寸等因素制约的难题，通过改进孔型系统，采用较小断面原料，成功试轧出14#角钢和20#槽钢。     

Development of butt welding of polymeric materials based on softening and stirring effects by hot tool

In this study, new butt welding technique was proposed to join polymeric materials in which the polymeric material is softened by a heated tool due to the Joule effect heating of the electric current flow through the tool, and the coalescence of material is done by the stirring action due to the tool rotation. A 3 mm-thick Polycarbonate (PC) sheets were joined in various joining conditions, from which joining mechanism, mechanical properties of joints and process parameters affecting joint performance were investigated. In the experiments, in situ observation with a CCD camera and material temperature measurement during the process, as well as the observation of surface appearance and cross section of the joint and tensile test were performed for these purposes. It was shown from the in situ observation and material temperature measurement that the molten and softened region is formed around the weld tool. It was also shown that sufficient heat input was required to form sound joints with acceptable performance, which depended upon the joining speed and amount of electric current flow through the tool. The observation of joint appearance and cross section revealed that the joint with comparable thickness to base material was obtained under the condition of revolution pitch below 0.08 mm, defined by the ratio of joining speed to tool rotation. It is noticed that joints obtained from the proper conditions have the same mechanical properties as the base material, and that the process parameters of this method were tool rotation speed, welding speed and amount of electric current. These results suggest proposed method is useful for joining the polymeric materials.     

Thermal spray manufacturing issues in coating IGT hot section components

The desire to improve the performance of gas turbine engines has led to higher operating temperatures in the turbine sections of the engine. Materials used for hot section turbine blades and vanes are not resistant to hot corrosion, and therefore require protective coatings. This paper reviews the current art and technology of thermally sprayed MCrAlY and TB coatings onto hot section components. The issues in applying such coatings will be discussed, along with references to manufacturing issues on the shop floor. The difficulties inherent in applying a line-of-sight coating to complex geometries will be discussed. The testing, evaluation, and performance characteristics of typical coatings are discussed. Adapted from P. Sahoo et al., “Thermal Spray Manufacturing Issues in Coating IGT Hot Section Components,” Paper No. 97-GT-487, American Society of Mechanical Engineers, 1997.     

基于Python的ABAQUS数控弯管数值模拟后处理

弯管零件以其优良的性能,在各工业领域中得到了广泛应用。有限元数值技术的发展为研究管材弯曲问题提供了一种有效的途径,结果数据的有效提取和高效处理成为数控弯管数值模拟的关键问题。文章采用Python语言对ABAQUS后处理模块进行了二次开发,根据数控弯管的常见质量指标,实现了截面扁化率、壁厚变化率、回弹角的计算以及管件起皱判断等功能,并开发出友好的图形用户界面,以增强后处理模块的实用性。其后处理二次开发思路同样适用于其他塑性成形过程。     

Fireside corrosion in German fossil-fuel fired power plants. Appearence,mechanism and causes

Fireside corrosion in German fossil fuel-fired boilers is described out of the view of a laboratory engaged with failure analysis. With German boiler design and German fossil fuel ferritic steels can be used for the tubing in the evaporator and superheater section. Corrosion rates, which have to be expected normally are below 10 nm/h for evaporator tubes and below 25 nm/h for superheater tubes. The appearance of corroded tubes is described and discussed in respect of the corrosion mechanism. In the evaporator section enhanced corrosion risk is mainly due to an increased chemical load, namely reducing conditions or chlorine compounds in the combustion products. In the superheater section higher than normal metal temperatures and stresses, by which the integrity of the oxide layer is destroyed, are the most important factors for increased corrosion rates.     

TG480QZ汽车传动轴用钢组织性能的研究

通过试验获得了TG480QZ热轧板卷的屈服强度、抗拉强度和伸长率，均满足标准的要求，且具有良好的横向同板性能及纵向同卷性能；冲击试验结果表明其韧脆转变温度远低于-60 ℃；TG480QZ热轧卷板的显微组织为均匀细小的铁素体＋少量珠光体，钢中夹杂物为球状氧化物Al2O3；轧制面、横截面、纵截面晶粒尺寸相差很小，组织均匀。因此，TG480QZ热轧卷板具有良好的综合性能，能够满足汽车传动轴用钢的要求。     

激光与电弧相互作用时的电弧形态及焊缝特征

激光与电弧的复合热源在焊接过程中，由于激光的压缩与引导作用，可以在焊接速度增加时，电弧仍然较稳定。在去掉激光同轴保护气流而只采用TIG的保护气体进行保护时，由于激光同轴气体的冲击、压缩和冷却作用的消失，等离子气体将会随着电流、激光功率的增加而增大，因而引起焊缝横截面的变化。通过调整激光与电弧的规范参数，并用CCD摄取各参数下的电弧图像以分析等离子体的长大情况，然后将得到的焊缝沿横截面剖开。通过对各种参数下等离子体图像和焊缝横截面之间的相互的关系进行分析，得到与常规情况下相比熔宽较宽而熔深较浅的焊缝的焊接参数。这种产生涂敷型焊缝的参数可用于高速表层涂覆。     

圆管压扁-压弯连续变形过程有限元模型的建立及截面畸变研究

为研究圆管压扁-压弯连续变形过程中的截面畸变,基于有限元软件ABAQUS建立了该过程的三维有限元模型,并实验验证了其可靠性。分析了圆管压扁过程中的截面变化规律及弯曲下模圆角半径、模具与管材间的摩擦系数对成形过程截面畸变的影响。结果表明,圆管压扁过程中形成扁管直壁部分的材料在外层周向压应力、内层周向拉应力的合力作用下出现塌陷。形成扁管圆弧部分的材料在外层周向拉应力、内层周向压应力的合力作用下出现扁化。在无芯轴、有芯轴压扁成形前期,圆弧部分均出现扁化,且无芯轴压扁成形中期,直壁部分出现塌陷。但有芯轴压扁过程中芯轴的支撑作用不但抑制了直壁部分的塌陷,而且还矫正了成形后期圆弧部分的扁化。由于圆管压扁-压弯过程中模具与管材的接触区域始终不大,因此成形过程中弯曲下模圆角半径,及模具与管材间的摩擦系数,对截面畸变影响不显著。