【作者】 张庭凤；

【导师】 阎峰云；

【作者基本信息】 兰州理工大学 ， 材料加工工程， 2007， 硕士

【摘要】 镁合金是实用金属中最轻的金属材料，具有刚性佳，高的比强度，阻尼减震性好等特性，广泛用于制造3C产品、汽车零部件等领域。论文以压铸镁合金材料AM60B作为研究方向，以压铸工艺参数对AM60B镁合金组织性能的影响为主要研究内容，对镁合金材料的压铸工艺—组织结构—性能变化之间的相互关系和热处理工艺—组织结构—性能变化之间的关系进行了较深入系统的研究，同时研究了工艺参数的变化对流动性和薄壁件易产生侧表面裂纹倾向性的影响规律。通过正交实验，对AM60B镁合金的压铸工艺的研究结果表明，压铸工艺参数对镁合金AM60B各项性能影响的显著性由强到弱依次分别为：流动性—压射比压、浇注温度、模具温度、压射速度；抗拉强度—浇注温度、压射比压、模具温度、压射速度；延伸率—压射速度、浇注温度、模具温度、压射比压；冲击韧性—压射速度、浇注温度、压射比压、模具温度；硬度—浇注温度、模具温度、压射比压、压射速度。综合分析各因素，本实验条件下最优方案为：浇注温度680℃，模具温度170℃，压射速度3.0m/s，压射比压95MPa。AM60B属于可热处理强化的合金，但要严格控制温度区间，而且热处理后合金中通常存在缺陷，例如表面烧蚀、起泡、氧化、局部晶界过烧等。通过扫描电镜观察拉伸断口和冲击断口形貌，发现断口存在较多的气孔和疏松。AM60B压铸镁合金的断裂方式为解理断裂。薄壁镁合金铸件容易产生热裂纹，而热裂倾向受浇注温度、压射速度、模具温度的交互影响。在本实验条件下，当浇注温度680℃、压射速度3.0m/s、压射比压95MPa时，铸件产生裂纹的倾向最小。更多还原

【Abstract】 Magnesium alloys are the lightest metals that have been used in practice. Because of lower density ,high ratio of strength to density and others advantages, Magnesium alloy is an important Engineering structure materials used widely to produce 3C (computer, communication and consumption) and automobile products .Research works of this thesis aim at die cast magnesium alloys AM60B and mainly focus on the effects of die cast technic parameter on them. Die cast magnesium alloy are investigated systematically for the relations of their technics, microstructures, mechanical properties and heat treatment, microstructures, mechanical properties. And the effects of different technics on the fluidity and the trend of hot crack, which are thin plane, of magnesium alloys are discussed.An orthogonal experiment was used to evaluate the influence of die casting parameters on die cast technics of AM60B magnesium alloy. The results show that the factors influencing on properties of AM60B from the greatest to the smallest are following: on fluidity are injection specific pressure, pouring temperature, mould temperature and die filling speed; on tensile strength are pouring temperature, injection specific pressure, mould temperature and die filling speed; on elongation are die filling speed, pouring temperature, mould temperature, injection specific pressure; on impact toughness are die filling speed, pouring temperature, injection specific pressure, mould temperature; on HB hardness are pouring temperature, mould temperature, injection specific pressure, die filling speed. After analyse all die cast parameter, in the experiment, the mechanical properties of Mg die-casting AM60B were obtain preferable value, at the proper factors: pouring temperature is 680℃, mould temperature is 170℃, die filling speed is 3.0m/s, injection specific pressure is 95MPa.Heat treatment is fit for AM60B alloy, but the temperature must be rigid and after heat treatment, there are some common defects in the die-castings, such as surface ablation, dunk, oxidation, and grain boundaryburn partly.We can observe carefully the break surface by means of SEM, the fracture patterns of die cast magnesium alloy AM60B is cleavage fracture, and pull break surface as same as impact break surface. There are many porosities and different crack.The thin wall die-castings are prone of hot crack and the hot crack trend was affected by mutual relation between pouring temperature, mould temperature and die filling speed. In the experiment, the least hot crack can be obtained at the proper value: pouring temperature is 680℃, die filling speed is 3.0m/s and injection specific pressure is 95MPa.更多还原