7075高强铝合金构件冷成形强化机制研究

目的针对7075高强铝合金构件在固溶-淬火-时效处理过程中成形精度低的问题,提出了7075高强铝合金预强化冷成形工艺,研究7075高强铝合金构件冷成形强化机制。方法基于高强铝合金短流程高性能成形技术,经过固溶-时效处理,获得预强化处理的7075铝合金板料,使用预强化处理的7075铝合金板料冷成形试制帽形梁。通过拉伸试验、杯突试验测试预强化处理的7075铝合金板料及帽形梁力学性能,并通过透射电子显微镜试验解释7075高强铝合金构件冷成形强化机制。结果预强化处理的7075铝合金板料抗拉强度为540MPa,延伸率为19.3%,强度接近7075铝合金T6态强度水平,塑性接近7075铝合金O态塑性水平。杯突值为16.6 mm,达到7075铝合金O态的87%。使用预强化处理的7075铝合金板料冷成形试制的帽形梁表面质量良好,无破裂等情况。经过烤漆工艺后,帽形梁抗拉强度为(560±5)MPa,屈服强度为(480±5)MPa,与7075高强铝合金T6态强度相当。结论预强化处理的7075铝合金板料基体内部存在大量GPⅡ区组织,这有助于提高7075高强铝合金的强度和塑性。使用预强化处理的7075铝合金板料冷成形试制的帽形梁在烤漆工艺处理时,基体中部分GPⅡ区会转变为η'相,析出相的转变和加工硬化的结合提高了成形构件的强度,使其强度可以达到7075高强铝合金T6态强度水平。

人工神经网络技术在成形模具表面激光强化中的应用

基于人工神经网络基本理论 ,建立在成形模具表面激光强化中预测材料表面最高温度、强化效果的 BP网络模型。借助于 MATL AB仿真软件中的神经网络工具箱作为开发平台 ,将试验样本数据和经过试验验证的数值计算结果作为补充的样本数据用于 BP网络的训练 ,利用训练好的 BP网络对非线性的样本数据规律进行拟合 ,实现激光加工工艺参数的优化 ,为实际生产和加工提供有效的依据。

高强钢热冲压成形工艺及装备进展

从加热技术、成形-淬火冷却技术、变强度热冲压技术、新型高强钢材料热冲压、摩擦磨损和数值模拟技术等方面,阐述了其技术应用的现状以及未来发展趋势。当材料和装备确定之后,热冲压模具的设计、制造和维护是保证热冲压生产质量和效率的重点,着重对几种新工艺的模具结构做了介绍。经典的辊底炉生产线适应大规模生产,其高效率主要体现在生产节拍上。随着汽车产品的多样化,特别是在新能源车的开发和规模化生产之前,要求高强钢热冲压生产线更能够适应中小批量和多种材料（如高强铝合金）。这些新的需求,导致了多样化加热方式的研究,以及智能试验线的出现。辊底炉生产线、多层箱式炉生产线和智能试模线的研究及应用,推动了全球热成形生产和汽车轻量化的步伐。

用钛合金管坯成形零件时热强化和热处理规范对零件性能的影响

1 前言 强化成形过程,可保证提高一道工序的变形程度。最有效是采用机械强化和热强化相结合。正如实践所表明,在制造钛合金零件时最合理和最有效的是接触加热毛坯,由加热装置直接传热。 众所周知。

Effect of cold rolling deformation on microstructure evolution and mechanical properties of spray formed Al−Zn−Mg−Cu−Cr alloys

The impact of cold rolling deformation,which was introduced after solid solution and before aging treatment,on microstructure evolution and mechanical properties of the as-extruded spray formed Al−9.8Zn−2.3Mg−1.73Cu−0.13Cr(wt.%)alloy,was investigated.SEM,TEM,and EBSD were used to analyze the microstructures,and tensile tests were conducted to assess mechanical properties.The results indicate that the D1-T6 sample,subjected to 25%cold rolling deformation,exhibits finer grains(3.35μm)compared to the D0-T6 sample(grain size of 4.23μm)without cold rolling.Cold rolling refines the grains that grow in solution treatment.Due to the combined effects of finer and more dispersed precipitates,higher dislocation density and smaller grains,the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa,respectively.In comparison to the as-extruded and D0-T6 samples,the yield strength of the D1-T6 sample increases by 415 and 92 MPa,respectively.

Formability and strengthening mechanism of AA6061 tubular components under solid granule medium internal high pressure forming

A new technological process of tube forming was developed, namely solution treatment → granule medium internal high pressure forming → artificial aging. During this process, the mechanical properties of AA6061 tube can be adjusted by heat treatment to satisfy the process requirements and the processing method can also be realized by granule medium internal high pressure forming technology with the features of convenient implementation, low requirement to equipment and flexible design in product. Results show that, at a solution temperature of 560 ℃ and time of 120 min, the elongation of AA6061 increases by 313%, but the strength and the hardness dramatically decrease. At an aging temperature of 180 ℃ and time of 360 min, the strength and hardness of AA6061 alloy are recovered to the values of the as-received alloy. The maximum expansion ratio（MER） of AA6061 tube increases by 25.5% and the material properties of formed tube reach the performances of raw material.

Influence of process parameters on properties of AA6082 in hot forming process

The influences of process parameters on mechanical properties of AA6082in the hot forming and cold-die quenching(HFQ)process were analysed experimentally.Transmission electron microscopy was used to observe the precipitate distribution and to thus clarify strengthening mechanism.A new model was established to describe the strengthening of AA6082by HFQ process in this novel forming technique.The material constants in the model were determined using a genetic algorithm tool.This strengthening model for AA6082can precisely describe the relationship between the strengths of formed workpieces and process parameters.The predicted results agree well with the experimental ones.The Pearson correlation coefficient,average absolute relative error,and root-mean-square error between the calculated and experimental hardness values are0.99402,2.0054%,and2.045,respectively.The model is further developed into an FE code ABAQUS via VUMAT to predict the mechanical property variation of a hot-stamped cup in various ageing conditions.

Microstructure evolution and strengthening mechanisms of spray-formed 5A12 Al alloy processed by high reduction rolling

The extrusion preform of the spray-formed5A12Al alloy was hot rolled using high reduction rolling technology.By means of transmission electron microscopy(TEM),electron backscatter diffraction(EBSD)and energy dispersive spectroscopy(EDS),the microstructure evolution was studied and the strengthening and toughening mechanism was thereby proposed.The results indicate that discontinuous and continuous dynamic recrystallization occurred during the hot rolling deformation of the spray-formed5A12Al alloy.The grain size was significantly refined and the micro-scale grains formed.Partial dynamic recrystallization leads to a significant increase of dislocation density and cellular structure.The Mg atoms were distributed in the Al matrix mainly in the presence of solid solution rather than the formation of precipitate.High solid solution of Mg atoms not only hindered the dislocation motion and increased the density of dislocation,but also exhibited a remarkable solid solution strengthening effect,which contributes to the high strength and high toughness of the as-rolled sheets.The tensile strength and elongation of spray formed5A12Al alloy at room temperature after3passes hot rolling were622MPa and20%,respectively.

New constitutive model for the study of creeping solids

In this paper, a incremental form of constitutive laws for creeping studies are proposed. The equations are based on the concept of creep hardening surface. Damage effects were introduced to the new constitutive relations to study solids creeping effects with pre-existing damages. The present formula is easy to be adopted into other numerical procedures such as finite element methods.

德国罗斯勒（Roesler）公司并购瑞上Baiker公司

2007年1月1日起，德国罗斯勒（Roelsler）公司正式并购喷丸强化与强化成形表面处理技术专业公司——端士Baiker公司，开始了其战略扩张计划的第2个步骤。2004年德国Roesler公司收购了在民用和军用航空航天工业领域享有良好声誉的法国VaparBlast公司。

用钛合金管坯成形零件时热强化和热处理规范对零件性能的影响

本文研究了在成形时加热钛合金OT4（TC2）和OT4-1（TG1）管坯的规范和后续退火规范对零件的物理-机械性能和使用性能的影响。在研究结果的基础上确定了沿加热的大直径角形芯棒推进管坯法制造导管元件工艺过程的最佳规范。

Treatment of Rural Effluents Using Fortified Sand-Clay： Interaction Bacteria-Clay for the Formation of Biofilm

The ability of some Tunisian sand-clays in rural wastewater treatment was investigated in this study. The sand-clays were characterized by studying the mineralogical and geochemical characteristics using X-ray diffractometer and atomic absorption spectrophotometer （AAS）, respectively. Performance efficiency studies were conducted to determine the best combination ratio of sand-clay/pebbles. Sand-clay fortified with pebbles in the ratio 3：1 gave the optimum water purification while combination ratio 1：3 gave the least. The fortified sand-clays were used in the treatment of wastewater from rural locality. On the other hand, bacteria play an important role in determining the properties and behavior of clay minerals in natural environments and such interactions have great potential for creating stable biofilms and carbon storage sites in soils, but our knowledge of these interactions are far from complete. The purpose of this study was to understand better the effects of bacteria-generated biofilms on clay interlayer expansion. Mixtures of a colloidal, 2-water smectite clay and Pseudomonas aereginosae in a minimal media suspension evolve into a polysaccharide-rich biofilm aggregate in time-series experiments lasting up to 1 week. X-ray diffraction analysis reveals that upon aggregation, the clay undergoes an initial interlayer contraction.