Study on Processing Conditions of Aluminum Matrix Composites Reinforced with Boron Carbide Particles

Different pre-heating of boron carbide particles for reinforcement and different processing conditions were studied in this work. Being one of the most cost-effective industrial methods, conventional melt stir-casting route was utilized.Result showed that the boron carbide particles distributed well for a suitable pre-heating temperature and processed in air.No reaction product was found at the A1-B4C interfaces at the resolution limit of SEM used in that way.     

碳化硅颗粒强化铜基双梯度纳米结构复合材料的制备及性能

本研究通过改变β-SiC强化颗粒空间体积分数分布以及Cu基体晶粒尺寸大小分布,结合粉末冶金技术制备出碳化硅颗粒强化铜基双梯度纳米结构复合材料(Cu/SiC),实验结果表明Cu/SiC复合材料强化体与基体界面结合良好,材料的结构与性能呈明显的梯度变化特征,该复合材料的强化是主要由载荷转移、加工硬化、细晶强化三者共同作用的结果。     

Sintered Composites Based on Stainless Steel

The effect of the amount of chromium carbide addition on the properties of composites based on stainless steel of the austenitic class and their structure formation during sintering in a vacuum are studied. Compositions with 10, 15, 20, 25, and 30% Cr₃C₂ and also a content of 5% MoSi₂ addition are investigated. It is established that an increase in Cr₃C₂ content from 10 to 30% for all composites leads to an increase in hardness and wear resistance, but to some reduction in strength, and in some case a reduction in corrosion resistance.

     

Sintered Composites Based on Stainless Steel

The effect of the amount of chromium carbide addition on the properties of composites based on stainless steel of the austenitic class and their structure formation during sintering in a vacuum are studied. Compositions with 10, 15, 20, 25, and 30% Cr₃C₂ and also a content of 5% MoSi₂ addition are investigated. It is established that an increase in Cr₃C₂ content from 10 to 30% for all composites leads to an increase in hardness and wear resistance, but to some reduction in strength, and in some case a reduction in corrosion resistance.     

Structures and Properties of Iron Matrix Composites with Tungsten Carbide Particle by EPC-V Process

Ｍｏｄｅｒｎｉｎｄｕｓｔｒｙｍａｋｅｓｄｅｍａｎｄｓｏｎｗｅａｒｒｅｓｉｓ－ｔａｎｃｅｏｆｅｎｇｉｎｅｅｒｉｎｇｍａｔｅｒｉａｌｓ．Ａｓａｋｉｎｄｏｆｓｕｒｆａｃｅｔｒｅａｔｍｅｎｔｔｅｃｈｎｏｌｏｇｙ,ｃａｓｔｉｎｇｐｅｒｍｅａｔｉｎｇｔｅｃｈｎｏｌｏ－ｇｙｃａｎｓａｔｉｓｆｙｔｈｅｎｅｅｄｓｏｆｗｅａｒｒｅｓｉｓｔａｎｃｅｏｆｍａｔｅｒｉ－ａｌｓ,ｂｕｔｔｈｅｒｅａｒｅｍａｎｙｄｉｓａｄｖａｎｔａｇｅｓｉｎｔｒａｄｉｔｉｏｎａｌｃａｓｔｉｎｇｐｅｒｍｅａｔｉｎｇｔｅｃｈｎｏｌｏｇｙｗｈｉｃｈ…     

Effect of Fiber Diameter on Quasi-static and Dynamic Compressive Properties of Zr-Based Amorphous Matrix Composites Reinforced with Stainless Steel Continuous Fibers

In this study, two Zr-based amorphous alloy matrix composites reinforced with STS304 stainless steel continuous fibers whose diameters were 110 and 250 μm were fabricated by the liquid pressing process. Using a Hopkinson pressure bar, the compressive deformation behavior was investigated at a strain rate of about 10³ s^?1, and the results were then compared with those obtained under quasi-static loading. 65 to 68 vol pct of STS fibers were homogeneously distributed in the amorphous matrix, in which considerable amounts of dendritic crystalline phases were present. According to the dynamic compressive test results, shear cracks were formed at the maximum shear stress direction in the 110-μm-diameter-fiber-reinforced composite to reach the final failure. In the 250-μm-diameter-fiber-reinforced composite, fibers were not cut by shear cracks because the fiber diameter was large enough to restrict the propagation of shear cracks, while taking over a considerable amount of compressive loads over 1500 MPa. This composite showed the higher yield and maximum compressive strengths and plastic strain than the 110-μm-diameter-fiber-reinforced composite because of the sufficient ductility of STS fibers, the effective interruption of propagation of shear cracks, and the strain hardening of fibers themselves.     

高碳铬不锈轴承钢孪晶碳化物研究

研究了高碳铬不锈轴承钢“孪晶碳化物”（直线状和链状碳化物）的影响因素及形成原因,结果表明：加热温度达到1140℃,退火后开始出现沿晶界分布的链状碳化物;加热温度≥1160℃,退火后出现大量直线状和链状两种形态的碳化物。材料从高温直接冷却时,温度≥1080℃并且冷却速度≤80℃／h可能析出链状碳化物,并且温度越高冷却速度越慢析出的可能性就越大。直线状碳化物形成原因为：材料加热温度过高．晶粒长大的过程中晶界迁移时偶然发生堆垛错误形成了生长孪晶,在随后的退火过程中碳化物向奥氏体挛晶界面沉淀而形成,是真正意义上的孪晶碳化物。链状碳化物是由于材料过热或者局部过热,在随后冷却过程中碳化物沿奥氏体晶界析出而形成的,本质上是一种网状碳化物。     

SiC颗粒增强铝基复合材料制备工艺的发展现状

综述了SiC颗粒增强铝基复合材料的搅拌法、粉末冶金法、挤压铸造法、喷射沉积法、高能超声半固态复合法和高能球磨法等制备工艺的原理、特点、应用及其最新研究进展,并展望了未来的发展方向。     

颗粒增强金属基复合材料切削加工工艺的新进展

颗粒增强金属基复合材料有着优良的物理力学性能,在国防、电子、航空航天等领域有着广泛的应用前景.但由于加工困难.限制了其推广使用.切削加工是颗粒增强金属基复合材料的精密和超精密加工主要手段,切削技术的进一步研究和发展是促进颗粒增强金属基复合材料应用的关键之一.据此,从复合材料切削加工的切削机理、切削刀具和表面完整性三个方面,介绍了国内外最新的研究成果,并指出了存在的问题和研究方向.     

碳化硅颗粒增强铝基复合材料的制备工艺进展

综述了碳化硅颗粒增强铝基复合材料(SiCp/Al基复合材料)的研究进展,重点阐述了SiCp/Al基复合材料的主要制备工艺,并在此基础上展望了其相关及后续工艺的研究方向.     

薄带连铸304不锈钢碳化物析出及溶解过程的原位观察

 采用激光共焦扫描显微镜原位观察薄带连铸304不锈钢高温下碳化物的析出及溶解过程。结果表明,薄带连铸304不锈钢在600 ℃开始析出碳化物,首先从晶内析出,而后从晶界析出,碳化物析出量随温度升高逐渐增加,到900 ℃时,析出量最大;1 006 ℃时,碳化物开始溶解,1 049 ℃时,大部分碳化物迅速溶解,1 155 ℃时,碳化物完全分解溶入基体,其溶解过程为δ→M23C6+δ′→γ。碳化物析出与薄带连铸铸带凝固组织及后续冷却过程有关。     

改善不锈轴承钢9Cr18共晶碳化物的工艺研究

采用金相显微镜分析了30 t EAF-LF-VD-Φ200 mm电极-Φ360 mm ESR锭-120 mm×120 mm锻坯-Φ50 mm轧材的冶炼和加工工艺对不锈轴承钢9Cr18共晶碳化物的影响,结果表明,模铸电极浇注温度由1500～1510℃降至1485～1495℃,电渣重熔熔速由4.5 kg/min降至3.5 kg/min,增强电渣重熔冷却条件,可以有效减少冶炼过程中的共晶碳化物原始形成。采用锻透力强、大变形开坯,可使大颗粒碳化物破碎、减小颗粒尺寸,降低碳化物条带和网状聚集程度,能够有效改善不锈轴承钢共晶碳化物评级,减小碳化物颗粒尺寸。     

Separate Evaluation of the Kinetics of Carbide Precipitation Occurring at the Interface of Preexisting Particles and Within the Austenitic Matrix in a Microalloyed Steel

The isothermal kinetics of carbide precipitation occurring at the interface of preexisting (Ti,Nb)(N,C) particles and within the deformed γ-austenite matrix were separately evaluated using a Nb-Ti-V microalloyed steel through small-angle neutron scattering and transmission electron microscopy. While the specimen was isothermally held after deformation at 1223 K (950 °C), (Nb,Ti)(C,N) particles were precipitated at the interface of coarse (Ti,Nb)(N,C) particles preexisting in the recrystallized γ matrix. This resulted in a single size distribution curve, which was converted from the measured magnetic scattering cross section. However, during isothermal holding after deformation at 1123 K (850 °C), fine (Nb,Ti,V)(C,N) particles formed mainly within the deformed γ matrix, although some of them were precipitated at the interface of preexisting coarse (Ti,Nb)(N,C) particles. Accordingly, the specimens held at 1123 K (850 °C) exhibited double size distribution curves. The separate evaluation between matrix and interface precipitation kinetics was successfully performed using the size distribution curves due to the difference in particle size according to the nucleation site. The reliability of carbide precipitation kinetics was confirmed by comparing the measured ratio between magnetic and nuclear scattering cross sections with the ratio calculated based on the measured chemical composition of precipitates.     

中国不锈钢市场与发展中的宝钢不锈钢事业

描述了世界不锈钢市场供需变化的基本特征、供需区域转移的基本趋势及中心转移的中国因素,剖析了中国不锈钢行业的竞争态势、机会与挑战,阐述并提出了宝钢进一步发展不锈钢事业的主要方向:积极进取,实现不锈钢技术创新能力的提升;统筹规划,优化、整合宝钢内外不锈钢资源;立足国内,面向全球,开拓多层次不锈钢消费市场;扩大合作领域,营造具有可持续竞争能力的不锈钢供应链;努力维护不锈钢行业持续、健康发展的良好环境.