SLOW PROPAGATION OF FATIGUE CRACK NEAR THRESHOLD

The effect of pearlite interlamellar spacing(d)from 0.31 to 0.77 μm of T8 steel on fatiguecrack propagation near threshold has been investigated at different stress ratios(R).Theclosure stress intensity factor(K_(cl)),the threshold value(ΔK_(th))and crack tip opening dis-placement range(ΔCOD)were measured.The results show that pearlite interlamellar spac-ing in this range has no effect on K_(cl),but has effect on the threshold value in low stress ratio.The threshold value is higher for materials with larger interlamellar spacing.No matter whatthe stress ratio is,during the propagation near threshold,the propagation rate will be thesame,provieded the crack tip opening displacement range is the same.Metallurgical examinations were also carried out to show that the crack propagationpath is sensitive to mierostructure.The crack always propagates along either boundary ofpearlite colony or ferrite lamellar in pearlite.     

Ni-Cr-Mo三元系1358 K等温截面的测定

应用三元扩散偶技术测定了Ni-Cr-Mo三元系1358 K的等温截面,借助电子探针微区成分分析方法分析了Ni-Cr-Mo三元扩散偶的相区成分,并对其相关系进行了研究.测得Ni-Cr-Mo三元扩散偶在1358 K下存在一个中间化合物NiMo,Cr和Mo在扩散偶中形成连续固溶体,Ni和（Cr,Mo）有限固溶,扩散偶中未发现三元中间化合物.实验发现Ni-Cr-Mo三元系1358 K的等温截面存在一个三相区：Ni＋NiMo＋（Cr,Mo）.     

简单断面孔型计算机绘图系统简介

介绍了简单断面孔型计算机绘图系统的编制方法、使用范围 ,计算机绘图的步骤及特点     

Numerical analysis of dimension precision of U-shaped aluminium profile rotary stretch bending

In order to enhance the dimension precision of bent part, advanced bending technologies is requested recently. Rotary stretch bending（RSB） is a suitable technology to realize high precision of bent part. The effect of processing parameters, namely the side pressure and the stretching force, on the dimension precision of aluminium profile RSB part was studied by finite element method. The numerical simulation of the U-shaped aluminium profile RSB was carried out, and the validity of the simulation was checked. Parametric analysis shows that the section distortion of the U-shaped profile LY 12M bent part decreases with the increasing of the side pressure, whereas the springback of curvature increases, and that both of the section distortion and the springback of curvature decrease with the increasing of the stretching force, moreover, the uniformity of curvature of the bent part is clearly enhanced with the increasing of the stretching force. The results above prove that RSB technology can better improve the dimension precision of aluminium profile bent part.     

Determination of isothermal section of Fe-Ti-Zr ternary system at 1173 K

Phase relations in the Fe-Ti-Zr ternary system at 1173 K were investigated by means of diffusion-triple approach together with electron probe microanalysis（EPMA） technique. A series of tie lines and tie-triangles were determined and the isothermal section at 1 173 K was established, which consists of four three-phase fields： β（Ti, Zr）＋FeZr2＋FeTi, FeZr2＋FeTi＋Fe2Zr, FeTi ＋Fe2Zr ＋Fe2Ti and Fe2Zr ＋Fe2Ti ＋Fe. The results show that the largest solubility of Ti in Fe2Zr is about 11.3 %（mole fraction） and the solid solubility of Ti in FeZr2 is about 26.9%, the solid solubility of Zr in Fe2Ti is about 8.1% and the solid solubility of Zr in FeTi is 7.2%. The binary compound FeZr2 is nearly a linear compound. No ternary compound is found.     

形变氮化08F钢冲击断口的分形研究

利用垂直截面法测量了０８Ｆ钢经不同形变氮化复合后冲击断裂表面的分形维数。结果表明，材料的冲击能Ａ和沿裂纹扩展方向剖面Ｋｏｃｈ曲线的分形维数Ｄ地均随表变量的增而增加。分形维维数Ｄ与ｌｎＡ之间呈正变化的关系，且满足下列关系式：ｌｎＡｋ＝４９．４３ＫＦ－５１．４４。     

小型材上冷床制动距离计算

对小型材上冷床制动过程进行了分析 ,并给出了制动过程中各个阶段制动距离的计算方法 ,为小型型钢轧机设计时选择工艺参数和电气控制参数提供了参考。     

大学·高考·教研室

大学是与学院有所不同的高等学校。道、学、理是大学教育应该给予学生的主要内容。技、艺、术是学院教育应该培养学生的本领。形而上者谓之道 ,形而下者谓之器 ,大学应该形而上。随着高等学校统一毕业分配的淡化 ,新生入学的统一考试也应做相应的改革。每年的统考所花去的人力、财力、物力 ,所动员参加每项工作的教育、公安、交通、防疫、医疗 ,乃至质检、饮食、印刷等等部门和行业 ,犹如是全民动员。这些存在使“应试教育”的弊端无法化解。改变这种状况 ,可以考虑在“统”字上开口子。要提高本科生的教学质量 ,必须复兴教研室的功能。教研室是把教师孵化为知识使者的摇窝 ,它的存在和运行是教学质量的保证。     

双线活套的控制及参数确定

介绍了在小型材连轧生产中双线活套的控制特点以及活套参数的确定方法。     

龙开口水电站初期下闸蓄水规划设计与实施

龙开口水电站初期蓄水阶段,采用导流底孔闸门局部开启的过流方式,顺利下泄环保流量,满足环保要求。结合蓄水时间对下闸时机进行了深入分析,为合理决策下闸时机提供了依据,对类似工程有一定借鉴作用。