【作者】 王旭；

【导师】 袁晓光； 黄宏军；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2012， 硕士

【摘要】 采用传统铸锭冶金工艺制备的过共晶铝硅合金,因其组织中具有粗大多边形初晶硅相,导致对基体组织的割裂及多边形硅相尖角结构形成应力集中点,使合金的力学性能较低,无法发挥其低膨胀和高耐磨的性能潜力,限制了其应用。半固态成形技术通过半固态制坯和挤压成形工艺,可以细化初晶硅相,并使多边形的初晶硅相尖角球形化,可以达到提高合金性能的目的。为此,本文针对斜坡冷却工艺制备半固态坯锭及对合金组织与性能的影响开展了研究工作。本文设计了一种斜坡冷却装置,系统地研究了斜坡冷却工艺对铝硅半固态坯锭组织的影响,确定了适于铝合金半固态制坯的斜坡冷却工艺参数;利用合金强化原理设计了一种过共晶铝硅合金,研究了变质处理、二次加热、流变和触变成形工艺与合金组织与性能关系,并对合金进行了热处理。研究表明,影响半固态坯锭组织的斜坡冷却装置主要工艺参数是倾斜板长度、倾斜角,合适的浇注温度与斜坡冷却装置工艺参数的合理匹配是获得理想半固态组织的关键。合适的半固态坯锭制备工艺参数为:倾斜板长度650mm、倾斜板斜坡倾角45°;合金浇注温度600℃-625℃;对于Φ10 mm×15mm圆柱形试样的合适二次加热参数为:二次加热温度585℃、保温时间20-30min。实验尺寸加大后,二次加热温度和保温时间应适当提高或延长。挤压参数:挤压头挤压行程:125mm;充型速度:2mm/s;保压时间:60s;模具加热温度:500℃,半固态成形态抗拉强度227.04MPa、硬度121HB、伸长率1.78%。热处理之后抗拉强度达到了264.35MPa,比铸态提高了123.3%。实验结果表明:该合金经斜坡法半固态制坯后,α-Al基体球化、均匀化;在半固态成形后,粗大的针片状共晶硅消失,尖角钝化、圆整化,形成近粒状或短棒状相,大块初晶硅被破碎或消除。在热处理工艺后,共晶硅形态和尺寸显著变化,更加圆整、细小,均匀。更多还原

【Abstract】 The traditional process of the preparation of bubble metallurgy of hypereutectic al-si alloy ,because of its organization with bulky polygons in primary crystal silicons, lead to base structure of separate and polygon silicon phase structure form stress midpoint pointed horn, make the mechanical properties of the alloy low, cannot play its low inflation and high wear-resisting performance potential in order to limit its application. Semi-solid forming technology through semi-solid blocking and extrusion forming technology, primary crystal silicons can be refined, And primary crystal silicons polygon pointed horn of spherical, can achieve the purpose of improving alloy performance.In this project, slope cooling process preparation semi-solid casting pieces on microstructure and properties and the influence of the research work carried out.This subject introduces a design slope cooling device system, the slope cooling process half-and-half solid billet pieces of the influence of the organization. make sure the suitable for semi-solid aluminum alloy cooling process parameters of blocking slope Using alloy strengthening principle designed a kind of hypereutectic al-si alloy, the bad treatment secondary heating rheological and touch into shape technology and alloy organization and performance relationship, and make the heat treatment of alloy.The project by Extensive Experimental Studies, get process parameters Eventually include: The optimal semisolid alloy blank parameters: Tilt board length: 650 mm;Tilt board slope Angle: 45°Tilt board pouring temperature: 600℃-625℃; The optimal parameters of reheating:Φ10mm×15mmcylindrical specimens: Heat preservation temperature: 585℃; Holding time: 20-30 min,Φ80×70mm billet pounds Heat preservation temperature: 595℃; Holding time:120min; Extrusion parameters: Extrusion head extrusion trip: 125 mm; The filling speed: 2mm/s; The holding time:60s; Mould heating temperature: 500,semi-solid forming tensile strength reach 227.04MPa,rigidity HB121,elongation 1.78%,after heat treatment tensile strength reached 264.35MPa,than as-cast improved 123.3%.Experiment results show: the semi-solid blocking alloy by slope method,α-Al Matrix spheroidizing and homogenization; after semi-solid forming, eutectic silicon phase with Bulky needle flake disappeared, Sharp-angled passivation and roundness , formation of granular or short clavite phase, huge primary silicon phase being broken and eliminated. After heat treatment,shape and size of eutectic silicon phase change prominently, become more roundness,wee,uniformity.更多还原