The Changeless Technique Researches for City Flood Control and Reduced the Disaster

1Introduction Throughsuccessiveeffortofthescientists,as H.Bergson,I.Koyr啨,I.PrigogineandS.C.Ouyang,formorethan40years,finallypeopleareunderstandingthatquantitativeanalysissystem sinceNewtonisnotevolutionscience.AndS.C.Ouyangsubstantiallyhasputforwardthestability principleofquasi three circulationsystemofthestirringenergyconservationlaw,involvingsystem restrictionofsubstanceexistenceaswellas methodofevolutionaryanalysis[1-4].Traditional quantitativeanalysismethod,asestimationmethodofprodu…     

2A12-T4铝合金再填充搅拌摩擦点焊过程中的材料流动行为和微观组织演变

In this study, we used the stop-action technique to experimentally investigate the material flow and microstructural evolution of alclad 2A12-T4 aluminum alloy during refill friction stir spot welding. There are two material flow components, i.e., the inward- or outward-directed spiral flow on the horizontal plane and the upward- or downward-directed flow on the vertical plane. In the plunge stage, the flow of plasticized metal into the cavity is similar to that of a stack, whereby the upper layer is pushed upward by the lower layer. In the refill stage, this is process reversed. As such, there is no obvious vertical plasticized metal flow between adjacent layers. Welding leads to the coarsening of S (Al₂CuMg) in the thermo-mechanically affected zone and the diminishing of S in the stir zone. Continuous dynamic recrystallization results in the formation of fine equiaxed grains in the stir zone, but this process becomes difficult in the thermo-mechanically affected zone due to the lower deformation rate and the pinning action of S precipitates on the dislocations and sub-grain boundaries, which leads to a high fraction of low-angle grain boundaries in this zone.     

搅拌摩擦焊技术应用与研究

 在搅拌摩擦焊技术发展的10余年间,从最初的铝合金焊接发展到多种金属轻合金和非金属材料的焊接,因其固相连接的技术优势得以迅速推广。文中对搅拌摩擦焊技术研究的成果与主要研究方向予以阐述,总结了焊接材料、搅拌头结构与材料、金相组织结构与力学性能、运动学和动力学模拟,以及焊接工艺与设备研究现状与应用前景。对于焊接材料研究,已经涉及具有高温流动塑性的金属和非金属材料;各类焊接材料与搅拌头结构及焊接工艺参数的工艺数值优化也在不断规范;金相组织结构与力学性能的研究则为焊接机制研究及搅拌摩擦焊的推广应用提供理论依据;运动学和动力学模拟作为焊接工艺参数优化手段得以广泛使用;搅拌摩擦焊设备的研制国内已经起步,并由单一的固定式搅拌摩擦焊机向多种类型、智能虚拟化方向发展,为搅拌摩擦焊的推广奠定基础。随着搅拌摩擦焊技术研究和应用的深入,对连接技术的发展产生巨大的冲击和推动,特别是航天航空领域的应用,必将带动搅拌摩擦焊技术在国民经济各行业装备制造过程中的迅速发展,具有非常光明的应用前景。     

LF21铝合金薄板搅拌摩擦焊组织与性能

采用搅拌摩擦焊方法对厚度为1.4 mm的LF21铝合金薄板进行单道对接焊实验。实验结果表明:在旋转速度为1 500 r/min,焊接速度为100~180 mm/min时,均可获得较好的焊接性能,焊缝的抗拉强度在125~134 MPa之间,焊接强度系数为基材强度的78%~83%,说明该铝合金薄板采用搅拌摩擦焊方法的焊接适应性好。硬度测试结果表明焊缝发生了软化,其软化区宽度约为25 mm。在焊接热循环的作用下,锰在焊缝区沿轧制方向析出并聚集成较粗大的脆性MnAl6化合物,降低了焊缝的抗拉强度。     

搅拌摩擦加工IF钢的组织性能

对3 mm厚的DC04冷轧IF钢板进行搅拌摩擦加工,研究加工区域的微观组织与力学性能. 在旋转速度为950 r· min-1 ,加工速度为60 mm·min-1时,采用加工后强制冷却技术可获得光滑平整且没有缺陷的加工表面. 搅拌摩擦加工后组织显著细化,加工中心的平均显微硬度约为HV 135. 6,是母材硬度的1. 4倍,表面细晶层硬度最高可达到HV 312. 8,细晶层和过渡层的抗拉强度分别比母材的抗拉强度提高50. 9%和47. 6%,加工前后试样的拉伸断口均呈微孔聚合韧性断裂特征. 细晶强化对材料抗拉强度的提高起主要作用.     

钢/铝回填式搅拌摩擦点焊接头界面形貌和组织研究

采用回填式搅拌摩擦点焊实现了钢和铝合金板的连接。利用光学显微镜、扫描电子显微镜和电子探针X射线显微分析仪等设备观察了钢/铝点焊接头的界面形貌,并分析了钢/铝点焊接头的力学性能与界面形貌的关联机制。结果显示,钢/铝点焊接头的断裂类型为钮扣断裂,力学性能较好。钢/铝点焊接头结合良好,未见明显的焊接缺陷。在钢/铝点焊接头界面处可以观察到钩状结构和漩涡结构,这些结构提供机械互锁效果,有利于母材的结合。钢/铝点焊接头界面处形成了主要元素为Al、Fe和Si的金属间化合物层。有效的冶金结合和机械结合是钢/铝点焊接头性能良好的主要原因。     

6082-T6铝合金回填式搅拌摩擦点焊接头的性能

针对2mm的6082-T6铝合金薄板进行回填式搅拌摩擦点焊,研究搅拌套的旋转速度及下扎深度对力学性能的影响规律,并对接头的横截面及断口形貌进行观察和分析.结果表明:当采用合适的焊接参数时,回填式搅拌摩擦搭接点焊的接头成形美观.点焊接头剪切强度随着搅拌头转速和下扎深度的增加均呈先增大后减小的趋势,剪切断口的断裂形式为韧性断裂.     

Effect of reinforcement content on the adhesive wear behavior of Cu10Sn5Ni/Si3N4 composites produced by stir casting

The main objective of this paper was to fabricate Cu10Sn5Ni alloy and its composites reinforced with various contents of Si3N4 particles (5wt％,10wt％,and 15wt％) and to investigate their dry sliding wear behavior using a pin-on-disk tribometer.Microstructural examinations of the specimens revealed a uniform dispersion of Si3N4 particles in the copper matrix.Wear experiments were performed for all combinations of parameters,such as load (10,20,and 30 N),sliding distance (500,1000,and 1500 m),and sliding velocity (1,2,and 3 m/s),for the alloy and the composites.The results revealed that wear rate increased with increasing load and increasing sliding distance,whereas the wear rate decreased and then increased with increasing sliding velocity.The primary wear mechanism encountered at low loads was mild adhesive wear,whereas that at high loads was severe delamination wear.An oxide layer was formed at low velocities,whereas a combination of shear and plastic deformation occurred at high velocities.The mechanism at short sliding distances was ploughing action of Si3N4 particles,which act as protrusions;by contrast,at long sliding distances,direct metal-metal contact occurred.Among the investigated samples,the Cu/10wt％ Si3N4 composite exhibited the best wear resistance at a load of 10 N,a velocity of 2 m/s,and a sliding distance of 500 m.     

减灾、防灾与“给能量留有空间”的对策问题

根据欧阳首承提出的“搅动能守恒定律”揭示的能量不能脱离物质,而必须给能量留有空间的理论,论述了能量空间与自然灾害和灾变动力的相互关系和作用,给出了能量空间在灾后重建工程、防洪减灾规划和生态环境规划等的应用和对策。并强调自然灾害、人为建筑工程“必须给能量留有空间”,才能更为有效地防灾、减灾。提出了“给能量留有空间”是针对当代科学遗漏了能量空间问题提出的新的科学命题。     

混凝土搅拌运输车拌筒恒速控制系统数学模型

混凝土搅拌运输车拌筒的转速直接影响混凝土的搅拌质量,使其拌筒在较低转速下恒速转动能保证混凝土的搅拌质量,因此,建立拌筒恒速控制系统数学模型,研制开发和载重相匹配的混凝土运输车拌筒恒速控制器很有意义。