Effect of Different Amounts of Graphite on the Sintering and Transverse Rupture Properties of Powder Metal Parts

Iron powders were mixed with graphite powders by 1-15 wt pct to produce block samples using powder metallurgy technique. The powders were blended in a three dimensional blender for 20 min and compacted in a die under 500 MPa by using a one directional press. Sinterability and mechanical properties of the samples with different carbon content were investigated. Sintering process was carried out on a belt furnace with flame curtain in dissociated ammonia atmosphere. Block samples produced were suitable for ASTM B-312 transverse rupture strength test apparatus and were tested with 0.050 kN/s velocity in a press under 100 g load. It was found that graphite amount up to 2 wt pct increased the contact area of particles and acted as a lubricant to affect the sintering behaviour positively. The results indicated that the samples containing up to 5 wt pct showed good sintering behaviour and also good hardness due to an increase in pearlite amount. However, the samples containing higher amount of graphite （more than 5 wt pct） affected the sintering behaviour negatively due to the settlement of free graphite around the Fe powders, which resulted in a decrease in the hardness and transverse rupture strength.     

Hot Deformation Behavior of 2124 Al Alloy

The mechanical behavior of 2124 Al alloy produced by powder metallurgy was investigated with compression test at different temperatures and strain rates. The tests were performed in the temperature range of 300℃～500℃ and at strain rates from 0.001 s^-1 to 1.0 s^-1. The compression flow curves exhibited an initial sharp increase with strain, followed by monotonous hardening. The maximum stress decreased with decreasing strain rate and increasing temperature. The hot deformation characteristics of the material were studied using processing maps. The domain of safety and unsafe regime were identified and validated through microstructural examination.     

激光表面改性技术的现状与展望

激光是一种受激放大的光源,它具有高亮度、高方向性、高单色性、高相干性以及特殊的空间分布特性、时间控制特性、偏振特性等独特的性能.激光加工技术涉及到光学、材料学、化学、物理冶金学、计算机、数控、机电及传感检测控制技术等,是多学科交叉的综合集成.     

迟暮夕阳余热暖，情真意切育英才——热烈庆祝师昌绪院士荣获2010年国家最高科学技术奖

师昌绪,物理冶金学家、材料科学家、战略科学家,中国科学院院士,中国工程院院士,第三世界科学院院士。他于1952年获美国欧特丹大学冶金博士学位,1955年回国,历任中国科学院金属研究所所长、中科院技术科学部主任、国家自然科学基金委员会副主任、中国工程院副院长等,现为国家自然科学基金委员会特邀顾问、     

2011年全国冶金安全环保学术交流会议在青岛召开

由山东金属学会、河北省冶金学会、江苏省金属学会、山西省金属学会、河南省金属学会、湖北省金属学会、湖南省金属学会、北京金属学会、陕西省金属学会共同举办,山东金属学会具体承办、山东国舜建设集团协办的"2011年全国冶金安全环保学术交流会议"于2011年9     

《材料与冶金学报》简介

《材料与冶金学报》(Journal of Materials and Metallurgy)是专业学术性刊物,由东北大学主办国家教育部主管。2002年3月创刊,季刊,80页,中文版,国内外公开发行。每期设有冶金、材料备、材料、环境等栏目。主要学术论文包括理论基础、工艺技术(侧重工艺上的原则,且带有普遍义)。材料栏目下的论文以金属材料为主;环境栏目下的论文,刊登与冶金相关的环境     

提高高性能厚钢板HAZ韧性的技术

1前言 厚钢板几乎都是用作结构用钢,从安全考虑最重要的是确保连接母材的焊接区韧性。要特别避免令人担心的焊接热影响区（Heat Affected Zone：以下记作HAZ）的韧性恶化,作为应对措施,早就知道了HAZ组织微细化是有效的。而HAZ组织微细化技术,对氧化物为中心的复合夹杂物（主要是在炼钢阶段产生的氧化物上结晶、析出硫化物、氧化物等复合夹杂物）的晶粒内相变控制技术等进行了广泛研究,这项技术被称作氧化物冶金学。     

Cooling γ precipitation behavior and strengthening in powder metallurgy superalloy FGH4096

Two cooling schemes (continuous cooling and interrupted cooling tests) were applied to investigate the cooling γ precipitation behavior in powder metallurgy superalloy FGH4096.The effect of cooling rate on cooling γ precipitation and the development of γ precipitates during cooling process were involved in this study.The ultimate tensile strength (UTS) of the specimens in various cooling circumstances was tested.The experiential equations were obtained between the average sizes of secondary and tertiary γ precipitates,the strength,and cooling rate.The results show that they are inversely correlated with the cooling rate as well as the grain boundary changes from serrated to straight,the shape of secondary γ precipitates changes from irregular cuboidal to spherical,while the formed tertiary γ precipitates are always spherical.The interrupted cooling tests show that the average size of secondary γ precipitates increases as a linear function of interrupt temperature for a fixed cooling rate of 24℃/min.The strength first decreases and then increases against interrupt temperature,which is fundamentally caused by the multistage nucleation of γ precipitates during cooling process.     

超精细粒钢中焊接HAZ晶粒长大规律

根据传统金属学和焊接冶金学理论,对800 MPa和400 MPa两个强度级别的新一代钢铁材料进行了焊接热模拟试验,分析了焊接热影响区HAZ晶粒长大规律.结果表明,随着Tp和t8/5的逐渐增大,新一代钢铁材料焊接HAZ的奥氏体晶粒都存在严重的长大倾向,且400 MPa级较800 MPa级的HAZ奥氏体晶粒长大更为严重.     

某金矿地质冶金学模型中采矿参数赋值北大核心

地质冶金学模型包含众多参数,对矿山生产的全流程有着指导作用,而对于采矿生产的指导意义尤为直接。在吉家洼金矿地质冶金学模型中,结合工程地质数据,对采矿方法、采场结构参数、贫化率和采矿成本参数进行了准确赋值。首先基于工程地质块模型中综合稳定参数和矿体厚度,将矿体划分为三类区域,分别适用于空场嗣后充填采矿法、下向进路充填采矿法和留矿采矿法,并在相应区域内,获得采场结构参数,并据此建立线框模型。进一步采用单一域赋值法,在地质冶金学模型中增加采矿方法和采场结构参数字段。采矿贫化率赋值是通过将试验采场内的局部点贫化率和矿体厚度做散点图,然后在三类采矿方法对应的区域内,求得三类贫化率回归方程,并利用回归方程在模型中赋予贫化率字段。采矿成本的计算以矿房为单位,计算矿房中辅助材料、燃料、动力、生产职工薪酬和制造费用的总和,然后根据模型块尺寸占所在矿房的比例来分担整个矿房的成本费用。地质冶金学模型中采矿参数和工程地质块模型中综合稳定参数及矿体厚度动态关联,采矿参数的优化依赖于工程地质模型中综合稳定参数。