第19届国际压铸会议及展览会述评

介绍了世界最大的压铸展览会展出的新产品、新材料、新技术的主要内容和学术会议５９篇论文综合概况及在计算机、锌合金、工艺、镁合金、过程控制、铝合金、压型材料、压铸机及其相关设备、压型涂料及表面处理、环境保护和安全以及先进技术研究和开发等１１方面的摘要供读者参考。     

Controlled Shot Peening to Prevent Fatigue and Stress Corrosion Cracking

Controlled Shot-Peening is a pre-stressing technique conducted to impart a residual compressive stress of known magnitude and depth to metallic materials. The technique is used by aerospace, automotive, agricultural, marine, offshore, medical, chemical and mining industries to prevent surface failures.

Nearly all component failures in any industry are surface related whether they be fatigue, stress corrosion, fretting, galling, spoiling or intergranular corrosion, and can be influenced beneficially by surface cold work, being related to surface stress, hardness and/or roughness.

This paper describes how the process is conducted, with details of the compressive stress, hardness and surface roughness induced; how the process has developed and where the future lies with the latest computer monitored techniques. These latest control techniques enable Shot-Peening to be used as a design tool, as well as a remedial treatment.     

超声冲击改善P355NL1钢焊接接头腐蚀疲劳性能研究

对P355NL1钢焊接接头进行超声冲击处理,研究超声冲击对腐蚀疲劳性能的影响。利用光学显微镜和扫描电镜对超声冲击前后的表层显微结构以及腐蚀疲劳失效断口进行分析,利用电化学工作站对超声冲击前后试样电化学腐蚀速率进行测定。结果表明,当试样处于6%(质量分数) NaCl腐蚀溶液中时,焊态试样疲劳强度下降12.5%;在6%NaCl腐蚀液和水介质中,冲击态试样相较于焊态试样疲劳强度分别提高了75%和53%,S-N曲线斜率分别改变75.4%和60.4%。经超声冲击处理后试样表层产生明显的塑性变形层,最大变形层深度约350μm;冲击之后试样的疲劳寿命有很明显提高,疲劳断裂位置也由焊趾处转移到焊缝或者母材区,腐蚀坑数目明显减少。表明超声冲击可以细化晶粒,同时降低应力集中现象,消除有害残余拉应力,引入有益的残余压应力,降低电化学腐蚀速率,提高焊接接头的腐蚀疲劳性能。     

International Workshop on High-Temperature Corrosion

The results of a third international workshop on New Knowledge and Open Questions of High-Temperature Corrosion that took place in August 1994 in Gohrisch, Saxony, Germany, are presented. The workshop was sponsored by Stiftung Volkswagenwerk and the Electric Power Research Institute (EPRI). Twenty-eight leading corrosion scientists from Europe, North America, and Australia participated. The discussion of nine subject areas in the form of key questions and proposed answers is presented.     

提高焊接接头疲劳强度的超声波冲击法

通常采用打磨焊趾的方法来改善焊接接头的疲劳强度,而使用超声波冲击焊趾来提高焊接接头及结构的疲劳强度,是一种国际上刚刚出现的新方法。本文研制成功了一种基于民陶瓷换能器的新型超声冲击试验装置。实际使用过程表明：其执行机构体积小、重量轻、噪音极小、耗能低、使用灵活方便,易于实施。利用该设备,采用Ｑ２３５钢进行了冲击处理 性对比疲劳试验。试验结果表明;超声冲击方法对妆接头疲劳强度的改善效果十分明显 ,能