置氢量对TC4钛合金激光焊接头组织相变及硬度的影响

采用光学显微镜(OM)、扫描电镜(SEM)和X射线衍射(XRD)等研究了置氢量分别在0%、0.05%、0.16%和0.37%时的TC4钛合金激光焊接头的显微组织及相变,并用数字显微硬度计分析置氢后接头硬度的变化规律,阐述其影响机制。结果表明:随着置氢量的增加,母材中的α相减少,β相增加;焊缝组织由针状马氏体α′相转变为片层状组织,且母材和焊缝组织向同一方向转变。接头显微硬度随置氢量的增加逐渐降低,且母材和焊缝的硬度差值逐步缩小,当置氢量为0.37%时,焊缝和母材的硬度差最小,为13 HV。置氢量影响TC4钛合金接头硬度的原因是接头中软化相β、氢化物δ和氢的固溶强化等引起的多种相变的作用。     

35CrMo钢的临界区热处理

研究了３５ＣｒＭｏ钢经不同温度临界区热处理后的显微组织与性能，并着重探讨了对其低温韧性的影响，试验结果得出：３５ＣｒＭｏ钢经临界区淬火并４７０℃中温回火后，与常规热处理态在保持等强度的同时，低温韧性有明显提高，－２０℃的冲击值提高８０％。     

TiC弥散强化铁基合金粉末的研究

ＴｉＣ弥散强化铁基合金粉末的研究吴军，王成国，孙康宁（山东工业大学）机械合金化是通过高能球磨使材料实现固态反应而合金化的一种方法。它是６０年代末期为研制氧化物弥散强化的高温合金而提出的［１］，近年来也出现了碳化物弥散强化材料的研究报道［２～５］。目前...     

手糊玻璃钢质量的控制

本文论述影响手糊玻璃钢质量的几个因素，同时对控制玻璃钢的质量提出了一些办法，对进一步提高玻璃钢的质量有一定的意义。     

一种含Nd耐热钛合金强化机制的研究

研究了Ｎｄ对Ｔｉ－５．５Ａｌ－４．５Ｓｎ－２Ｚｒ－１Ｍｏ－０．２５Ｓｉ－Ｎｄ耐热钛合金的组织，室温拉伸性能和热稳定性能的影响及其机制。结果表明，Ｎｄ可以细化组织，密化位错网亚晶界，改善室温拉伸强度和热稳定性能。Ｎｄ的强化机制主要由细晶强化（尤其是位错网亚晶强化）和基体中Ｓｎ，Ｏ贫化引起的弱化的综合。     

等离子体表面改性技术的发展

主要论述了等离子体技术在金属材料表面强化中的应用研究现状和发展趋势，特别是各种工艺的基本原理和应用优势。     

冷却速度对C-Si-Mn系热轧双相钢组织性能的影响

通过实际的热轧实验,研究了轧后冷却速度对C-Si-Mn系热轧双相钢组织形貌和力学性能的影响。研究发现,轧后冷却速度对热轧双相钢的显微组织和力学性能有很大的影响。热轧双相钢具有三种典型的组织形貌,而不同的组织形貌通过不同的强化机制赋予热轧双相钢不同的力学性能。通过不同冷却速度下的双相钢热轧实验,可以使热轧双相钢获得良好的力学性能。     

A new high strength and high tolerance-resistance A1-Li alloy

In order to develop a new high strength and high tolerance-resistance Al-Li alloy which can be used in aerospace industry, the effects ofmicroalloying elements such as Mg, Ag, Mn and Zn on the mechanical properties of Al-Cu-Li alloys were studied. The results show that the strengthening effects of Mg＋Ag and Mg＋Zn additions are higher than those of the individual Mg, Ag or Zn addition. The element Mn can also bring some extent strengthening effects on the alloys, but it has nothing to do with the other microalloying elements present or not. Finally, a new Al-Li alloy with Mg＋Zn＋Mn additions was developed, which possesses high strength and high tolerance-resistance promising properties for aerospace applications.     

Microstructure development of steel during severe plastic deformation

The microstructure development during plastic deformation was reviewed for iron and steel which were subjected to cold rolling or mechanical milling (MM) treatment, and the change in strengthening mechanism caused by the severe plastic deformation (SPD) was also discussed in terms of ultra grain refinement behavior. The microstructure of cold-rolled iron is characterized by a typical dislocation cell structure, where the strength can be explained by dislocation strengthening. It was confirmed that the increase in dislocation density by cold working is limited at 10¹⁶m⁻², which means the maximum hardness obtained by dislocation strengthening is HV3.7 GPa. However, the iron is abnormally work-hardened over the maximum dislocation strengthening by SPD of MM because of the ultra grain refinement caused by the SPD. In addition, impurity of carbon plays an important role in such grain refinement: the carbon addition leads to the formation of nano-crystallized structure in iron.     

ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION

This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques using experiment and thermodynamics theory. The experimental results show that there are lots of fine and dispersive precipitates in microstructures. By analysis, most of aluminum nitrides are in grains, while coexisted precipitates of MnS are along grain boundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3 in the core, while MnS is at the fringe of surface. The precipitation behavior of AlN and MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubility products.