大塑性变形制备纳米结构金属

细化晶粒是改善材料性能的有效手段，传统的压力加工技术(如轧制、挤压、拉拔和锻造等)可以细化晶粒(微米量级)。纳米结构金属由于具有很小的晶粒尺寸(20-500nm)和独特的缺陷结构，从而表现出优异的物理—力学性能。大塑性变形(SPD)具有将铸态粗晶金属的晶粒细化到纳米量级的巨大潜力，近年来已引起人们的极大关注。介绍了4种大塑性变形制备纳米结构金属的方法、原理、变形特点及应用，分析了纳米结构金属的强度和超塑性变形特征，以及当前研究中存在的主要问题，并对大塑性变形技术的应用前景进行了展望。     

Study on Hot Deformation Cracks of Steel D2 Using Procesing Map

ＳｔｕｄｙｏｎＨｏｔＤｅｆｏｒｍａｔｉｏｎＣｒａｃｋｓｏｆＳｔｅｅｌＤ２ＵｓｉｎｇＰｒｏｃｅｓｉｎｇＭａｐＧａｏＳｈａｎ，ＬｉｕＸｉａｎｇｈｕａ，ＷａｎｇＧｕｏｄｏｎｇＡＢＳＴＲＡＣＴＴｈｅｈｏｔｄｅｆｏｒｍａｔｉｏｎｂｅｈａｖｉｏｒｓｏｆｓｔｅｅｌ...     

内蒙古大青山麻粒岩相糜棱岩石英的变形行为

在内蒙古大青山地区发育一套高温区域变质岩──麻粒岩，在这高温变质岩内有一系列的糜棱岩带．通过对糜棱岩带中石英的研究，对比深部地壳与浅部地壳石英的变形特点，获得一些新的认识．对石英显微构造、动态重结晶、TEM研究及石英岩组学方面进行了研究，发现石英的塑性变形显著，以缎带石英产出，发育各种塑性变形的显微构造，变形带、波状消光和亚颗粒显著：TEM观察到石英中有直线状的位错．岩组学研究显示出石英高温变形和多期构造叠加的特点．     

CFRP强度复合Weibull分布的物理特征分析

本文对ＣＦＲＰ材料疲劳后剩余强度的复合Ｗｅｉｂｕｌｌ分布的物理特征进行了初步分析。指出树脂基复合材料失效（破坏）机理的双重性（基体和纤维失效模型）决定了剩余强度（累积损伤程度）测试结果的分布特征。复合Ｗｅｉｂｕｌｌ分布曲线的特征与分析结果对设计、使用及材料研究都有重要参考意义。     

川东地区井下套管损坏的原因分析及对策

本文就近年来在钻井施工中遇到的４口井发套管损坏的问题进行了原因分析，提出了防止井下套管损坏对策。     

A CONSTITUTIVE MODEL FOR ELASTIC-PLASTIC DEFORMATION UNDER CYCLIC MULTIAXIAL STRAINING

Abstract— The yield criterion is interpreted as defining the metric of the stress space. Hydrostatic stresses correspond to null geodesies. The plastic strain increment represents a normal projection of the increment undergone by a certain scalar function (hardening function) which depends only on the distance between stress points. This establishes a flow rule formally equivalent to the Prandtl-Reuss equations. Consideration of un-loading processes leads to the analysis of equivalent paths and to the definition of a generalized length or separation which provides a new representation of kinematic hardening.     

Nb,Ti微合金钢热变形的动态模拟变形抗力模型

本文报道 Nb,Ti 微合金钢的热变形动态模拟变形抗力模型。在试验中用热加工模拟试验机进行高温压缩试验,其变形温度为1123—1423K,变形速率为0.1—60s~(-1)。结果表明,在峰值以前该钢种的流变应力数学模型为:σ=5.99.ε~(0.167)·(?)~(6.47×10~(-5)·T)·exp(4064/T)。形变激活能(Q)为444 kJ/mol,β系数为0.080。峰值应力(σ_p),临界应变(ε_c)和温度补偿应变速率参数(Z)之间的关系分别为:σ_p=12.56·lnZ-391.8;lnε_c=0.157·lnZ-7.39。     

Corrosion fatigue short crack growth behaviour in a high strength steel

The influence of an aggressive environment (0.6 M, aerated NaCl solution) on short fatigue crack initiation and growth behaviour has been studied. The study involved three major test series, namely: air fatigue, corrosion fatigue, and intermittent air fatigue/corrosion fatigue. The above tests carried out under fully reversed torsional loading conditions at a frequency of 5 Hz, showed that it was the non-metallic inclusions which took part in crack initiation resulting from debonding at metal matrix/inclusion interface and pitting of inclusions in both air and corrosove environments, respectively. Short fatigue crack growth results in these two environments obtained by using plastic replication technique, indicated a large effect of microstructure i.e. prior austenite grain boundaries. The stage/stages at which the environmental contribution was dominant has been discussed by considering the results achieved from intermittent tests. However, the mechanisms involved in corrosion fatigue short crack growth have also been described in the light of results obtained from futher investigations carried out by conducting corrosion fatigue tests under applied cathodic potential conditions and tests on hydrogen pre-charged specimens under air fatigue and uniaxial tension conditions.     

低合金高强度钢的微观组织和疲劳裂纹扩展行为

用透射电镜观察了３０ＣｒＭｎＳｉＮｉ２Ａ钢等温的微观组织，疲劳裂纹扩展行为、裂纹尖端塑性区和位错结构，结果表明，等温状态组织由马氏体和贝氏体组成。在一个奥氏体晶粒内一般存在四个板条领域、裂纹尖端的塑性区内存在主位错带，疲劳断裂的基本组织单元为板条晶或板条束。裂纹遇到板条束界时方向发生较大偏斜。     

Failure analysis of a wire rope

Wire ropes, pulleys, counterweights, and connecting systems are used for auto tensioning of contact wires of electric railways. A wire rope in one such auto tensioning system suffered premature failure. Failure investigation revealed fatigue cracks initiating at nonmetallic inclusions near the surface of individual wire strands in the rope. The inclusions were identified as Al-Ca-Ti silicates in a large number of stringers, and some oxide and nitride inclusions were also found. The wire used in the rope did not conform to the composition specified for AISI 316 grade steel, nor did it satisfy the minimum tensile strength requirements. Failure of the wire rope was found to be due to fatigue; however, the ultimate fracture of the rope was the result of overload that occurred after fatigue failure had reduced the number of wire strands supporting the load.