Effects of different tempers on precipitation hardening of 6000 series aluminium alloys

By means of Vickers hardness,mechanical property and formability tests,the effects of different tempers on precipitation hardening of 6000 series aluminium alloys for automotive body sheets were investigated.The results indicate that the short-time pre-aging at 170℃makes for subsequent artificial aging precipitation hardening.With the increase of pre-aging time,the artificial aging hardenability increases.The aging hardening rate reaches the maximum when pre-aging time is up to 10 min,and then it decreases.The short-time pre-aging at 170℃benefits sheets to obtain lower strength under delivery condition and consequently to improve stamping formability of automotive body sheets.The effects of different tempers on precipitation hardening are much more obvious than those of the alloying elements.It is a good treatment schedule to perform pre-aging for 5 min at 170℃right after solution treatment.     

钛合金表面高能喷丸纳米化后的组织与性能

通过光镜、扫描电镜、硬度仪和透射电镜对TC4钛合金表面高能喷丸纳米化后的金相组织、晶粒尺寸、显微硬度进行测试分析。结果表明,处理后材料表面平均晶粒尺寸达到了纳米量级;在横截面上沿深度方向的晶粒细化程度逐渐减小;随距被处理表面距离增加,硬度增加程度越来越小;随处理时间延长,表面硬度有增加的趋势。并对其纳米化机理进行了讨论。     

面向高速切削的CAD模型与CAM编程

对复杂零件进行高速切削加工，往往先借助于CAD软件建立模型用于定义零件外型，然后通过CAM软件生成数控加工程序。CAD和CAM的质量与应用是影响高速切削加工质量的主要因素。深入分析并阐述了建立面向高速切削加工的CAD模型时需注意的事项，及如何合理地选用CAM系统提供的编程策略，以获得完美的走刀路径，生成优化的数控加工程序。并以连杆模具高速加工为例，对面向高速切削的CAD与CAM应用进行了介绍。     

过烧YAG陶瓷晶界的分析

采用固相反应法用不同的烧结速率在1850℃烧结合成过烧钇铝石榴石（YAG）陶瓷，YAG陶瓷晶界形貌随烧结速率的变化而不同。高纯的毋Al2O3和Y2O3原料粉体经高能球磨在1400℃空气中煅烧，生成主相为YAG相的多相粉体化合物。真空烧结YAG陶瓷时烧结速率800℃／h并在1850℃真空烧结4h会使陶瓷中晶粒长大不充分，晶粒与晶粒之间仍保留明显的面接触，陶瓷内部残存大量直径约1μm的气孔，尺寸与可见光波长接近，对透过率的影响大，陶瓷成半透明；在以100~C／h升至1850℃真空烧结4h的YAG多晶陶瓷半透明化，陶瓷晶粒粗大，晶界宽化且保留熔融态凝固，用TEM及EDS确认晶界处存在毋α-Al2O3和钙钛型YAP共晶相。     

无缝管轧制变形区内金属流动和摩擦力的实验研究

用自行设计的实验装置真实描述出无缝管轧制变形区内单位轧制力，纵、横向摩擦力的分布规律，绘制出变形区各点的摩擦力分布和金属流动轨迹图。     

450mm热连轧机组轧制带钢拓宽分析

讨论了邯郸钢铁公司一轧厂450mm热连轧带钢的拓宽问题；对该机组及其φ500mm开坯机进行了现场测试，并在计算机上进行了带钢拓宽模拟轧制，得出了该机组的最大轧制负荷及其带钢的拓宽限度。     

Evolution of {001 } （110） orientation and related lattice rotation of A1 alloy 6111 during rolling

The texture evolution and lattice rotation in A1 alloy 6111 with an initial {001} （110）component during symmetrical and asymmetrical roiling were investigated by means of orientation distribution function（ODF）. The results show that the as-rolled initial {001 } （110） orientation evolves into not only the copper orientation but also all the other orientations along the β fiber, including the brass orientation, by lattice rotation around special directions. Compared with the symmetrical rolling, the {001 } （110）component in the surface layer on the slower roller side evolves more quickly into the orientations along the β fiber during asymmetrical rolling, while that in the surface layer on the faster roller side evolves more slowly.     

Constitutive model of rock under static-dynamic coupling loading and experimental investigation

1 Introduction Rock fragmentation, boring, explosive, rockburst etc in engineering domain of mineral are almost concerned with cracking of rock experiencing dynamic loading, and a plenty of results have been obtained[1]. But the related studies are almos…     

百米磁场下降法测量埋地管道外涂层绝缘电阻技术

介绍了百米磁场下降法测量埋地管道外涂层绝缘电阻的技术，对施测手段、操作要点、计算方法及检测中应注意的问题进行了论述。     

ZNM—Ⅲ砂代替合脂砂的研究

介绍了ＺＮＭ－Ⅲ水玻璃复合改性粘结剂的制备工艺，ＺＮＭ－Ⅲ砂的最佳配方及性能，并探讨了改性机理。此种芯砂可替代合脂砂制作Ⅱ、Ⅲ级型芯。