Metallurgical Investigation of a Prematurely Failed Concentric Reducer Tube Used in a Hot-Rolling Mill

A concentric reducer tube, which was a part of the top exit roughing hydraulic descaler in a hot strip mill failed prematurely under working pressure. A detailed metallurgical investigation comprising physical examination, optical microscopy, scanning electron microscopy, and electron probe microanalysis was carried out to find out the genesis of the failure. Physical examination revealed cracks located symmetrically around the circumference of the tube that ran along its full length, up to the weld beads at both ends. Optical microscopy of etched samples revealed a banded ferrite-pearlite structure and the existence of forging folds near the change-in-section(160° fillets). Cracks were found to initiate from these forging folds. No structural abnormalities were found in the weld beads and heat-affected zones.     

饼形大锻件成形时的尺寸变化关系

本文推导出了饼形大镦件成形时的尺寸变化关系式,可指导锻压工人正确控制饼形件的镦粗成形,也可做为工艺员减少饼形件余量及公差的依据,对节能节材很有意义。     

锻造产品实现节材降耗生产的计算机技术

锻造过程中的材料消耗往往是很大的，依靠计算机技术可以实现较大幅度的节材降耗。文章阐述了节材降耗的原理，提出了节材降耗的技术手段和具体方法。运用该技术进行生产工艺改造，可节约锻造原材料和能耗10％～30％。     

空心钢锭锻造工艺的研究

介绍了30t空心钢锭锻造试验过程及所制产品的质量情况,以及用65t空心钢锭生产电站环形锻件情况,为用大型空心钢锭生产锻件的进一步研究提供了依据。     

3Cr2W8V钢锻件表面裂纹的成因及预防措施

通过对难变形钢3Cr2W8V进行实验,证明了合理地选择锻造工艺参数,也是解决表面裂纹的重要途径之一。     

基于AutoCAD的锻造工艺卡片设计系统

基于AutoCAD平台,运用Object ARX,使用VC7.0和Visual LISP开发了锻造工艺卡片设计系统.针对企业特定工艺卡片模板,读取其锻造工艺信息数据库,通过用户交互式修改,将文字信息正确输出到工艺卡片上,避免了以往手动生成和编辑卡片的麻烦.同时提供图纸管理和图纸打印功能,进一步提高工作效率.     

Lubrication and Friction of Magnesium Alloys in Warm Forging

In order to realize precision forging of magnesium alloys, the frictional behavior of ZK60 (Mg-6%Zn-0.5%Zr) is studied. At room temperature, the friction test of ZK60 sliding over the surfaces of cemented carbide tool with and without TiC+TiCN+TiN and DLC (diamond like carbon) coating is carried out. It is found that the DLC coated film is effective to reduce the coefficient of friction and the oxide film of magnesium increases friction. For warm forging, ring compression tests are carried out at temperatures from 200 °C to 300 °C. Several liquid lubricants are applied onto the tool surfaces by controlling the film thickness and the effect of lubrication on friction is examined. Some methods for heating and lubrication for warm forging of magnesium alloys are suggested.     

锻模型腔的电解加工技术

通过电解加工与其它常用加工方法的比较，以及电解加工应用的实例，论证了电解加工是提高锤模型腔加工水平的重要工艺手段。     

整锻支承辊锻造新工艺应用研究

本文介绍了第一重型机械集团公司分别用FM法和KD法,以及两种锻造法联合生产70Cr3Mo钢整锻大型支承辊的工艺及生产经验。使用这些工艺能实现轧辊内部良好压实,减少锻造火次,提高锻造生产率。     

浅述我国电液锤技术的发展与应用

通过对国外电液锤技术的引述，介绍了目前国内电液锤技术的发展与应用状况，并展望了电液锤发展前景。