奥氏体本质晶粒度与金相组织的关系

一、引言奥氏体本质晶粒度直接影响材料在高温和室温下的机械性能,因此,人们对它非常重视。工程上规定,奥氏体本质晶粒度大于5级的钢为本质细晶粒钢,小于4     

20—11PB钢的晶粒度及硬度控制方法的研究

在对２０－１１ＰＢ的研制过程中，采用了新的生产工艺，有效控制了晶粒度及硬度，通过机理分析，证明该方法对其它汽阀的研制的借鉴意义。     

铝合金管材晶粒度的细化研究

通过控制6063管材截面晶粒尺寸,来满足某高端汽车客户标准中100μm的晶粒尺寸要求;从铸棒的均质制度、模具设计方式、挤压工艺三个方面进行优化控制,通过高倍显微镜、电导率和布氏硬度等检测方法进行深入分析.结果表明,铸棒采用高温短时的均质制度,模具减少前室的设计方法,挤压工艺使用低温快速的挤压方式,成功生产出符合高端汽车...     

车轴钢晶粒度浅述

论述了珠光体的形成机理及Al和热处理制度对其的影响,表明适当的热处理制度可以细化LZ50钢的晶粒。     

晶粒度自动分析软件

根据国家标准ＧＢ６３９４－８６，利用ＫＳ４００型图像仪，编制了晶粒度自动分析软件。经测试，该软件具有准确度高，机动灵活，省时省力的特点。     

Influence of grain size on the hardness of alpha plutonium

The effect of grain size on the hardness of alpha plutonium was measured at temperatures between 77° and 373°K. The observations were: 1) fine-grained metal had the lowest hardness at 373°K, 2) fine-grained metal had the highest hardness at 77°K, and 3) fine-grained metal had the greatest temperature dependence of hardness. At room temperature, fine-grained α-plutonium (1 μm) had a hardness of 235 Dph, whereas coarse-grained metal (2000 μm) had a hardness of 310 Dph. At 373°K fine-grained metal had a hardness of 120 compared to 225 Dph for the coarse-grained metal. At 77°K the hardness values were 505 and 475 Dph, the fine-grained metal being harder at this temperature. The hardness was estimated to be independent of grain size at 140°K. Above 140°K, grain boundaries have a softening effect due to the contribution of grain boundary sliding to deformation.     

The relationship between grain size and the surface roughening behavior of Al-Mg alloys

The inhomogeneous surface deformation generated during metal forming presents significant challenges to the use of high-strength, lightweight alloys in automotive applications through the initiation of strain localizations that produce both tearing during metal forming and increased friction between mating die surfaces. Thus, a generic understanding of the relationships between plastic strain, grain size, and deformation-induced roughness at the free surface is needed before forming models can be fully developed to accurately predict the behavior and, ultimately, the changes in the friction within the dies. This research examines the roughening behavior of a solid solution strengthened, commercial Al-Mg alloy. The results of this evaluation indicate that the standard roughness measures increase with uniaxial plastic strain in a manner that can be represented by a simple linear estimate. The results also demonstrate that the roughening rate (dR _a/dɛ _pl) is dependent on the grain size in this alloy, and the relationship between the roughening rate and grain size also appears to be linear for the range of grain sizes included in this evaluation. However, examinations of the roughened surfaces reflect that the roughening process is a highly complex combination of mechanisms and it is strongly influenced by grain size. As a result, representing the complex changes that occur during roughening of a free surface by plastic deformation with a single number calculated from profilometry scans may be too coarse of a measure to fully describe these changes when modeling roughness-dependent behavior or properties.     

On the relation between grain size and grain topology

Experimental studies of the topology of grains in polycrystals have indicated that the topological complexity of a grain is related to its diameter, as opposed to its surface area or volume. This paper presents additional experimental documentation of this correlation and a theoretical derivation of the empirically observed relationship.     

千足黄金首饰的硬化工艺探讨

千足黄金首饰的硬化工艺是目前国内首饰行业关注的一个热点问题.根据金属材料硬化机理,结合黄金首饰不同生产工艺流程,提出了千足黄金首饰的硬化工艺为冶金法、渗氮法、纳米粉末法和电铸法,并对冶金法和渗氮法进行了探索性实验.实验结果表明,目前冶金法可实现千足黄金强度增大到维氏硬度85kg/mm2,渗氮法可增加到维氏硬度58kg/...     

二叠系龙潭煤系与黔西南金矿的关系研究

贵州最富的特大型微细浸染型金矿(水银洞金矿)产于上二叠统龙潭组中。龙潭组厚度为230~420m,含丰富的玄武质、凝灰质及硅质岩等,金平均丰度为250×10-9;沉积在大陆向海洋过渡的环境,沉积期伴随有西部峨眉山玄武岩的喷发及同生断裂控制的热水沉积,形成与煤系沉积相伴的特殊含金建造。此层位中金矿床(点)发现的频率较高,具有较大的找矿前景。     

双相碳钢性能与马氏体含量和晶粒大小关系初析

通过四种不同的分步淬火热处理工艺,相应地获得了四种不同组织的双相钢.研究表明,随着马氏体含量的增加,双相钢的最大拉伸强度随之增加,延伸率随着马氏体的增加而降低.试样的铁素体晶粒大小在不同的马氏体范围内对强度和延伸率有不同的影响.