Abstract

Based on the studies of its structure, as well as technological and mechanical properties, the composition and application prospects are substantiated for a high-strength aluminum Al–Zn–Mg–Ca–Fe casting alloy with no heat treatment. As the subjects of study, we have obtained alloys based on a composition of Al–5.5% Zn–1.5% Mg (wt %) jointly and separately alloyed with 0.5–1.0% Ca, and 0.5% Fe. As the reference, we used standard AK12M2, AMg6lch, and AM4.5Kd casting alloys corresponding to GOST (State Standard) 1583–93: by means of pencil sample casting, the alloy has been tested for the tendency to form hot cracks owing to hindered shrinkage. It is shown that separate alloying with calcium and iron does not promote any improvement of crack resistance and adversely affects mechanical properties. The combined alloying with 1% Ca and 0.5% Fe makes it possible to improve the parameter of hot tearing susceptibility to the level inherent in the AMg6lch alloy. This effect is caused by the formation of eutectic calcium-containing phases, and the formation of a favorable grain structure in which there are no columnar grains. Iron in the structure of the alloy is bound in compact particles, representing a Al₁₀CaFe₂ phase, which is a consequence of a nonequilibrium crystallization process occurring in the course of chill-mold casting. The formation of this phase makes it possible to reduce the amount of zinc in the (Al, Zn)₄Ca phase and mostly to conserve the composition of the (Al) solid solution, as is indicated by similar hardness values of the base Al–5.5% Zn–1.5% Mg alloy and Al–5.5% Zn–1.5% Mg–1% Ca–0.5%–Fe alloy, as well as the superiority of these values over the hardness values of alloys separately alloyed with calcium and iron. In addition, the hardness of the promising alloy in the as-cast state is more than 20 HV higher than the hardness of branded cast alloys in the same condition. The novel alloy in the as-cast state has shown the following competitive mechanical tensile properties: σ_UTS ~ 310 MPa, σ_0.2 ~ 210 MPa, and δ ~ 4%.

中文翻译：

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无需热处理的新型高强度铸造Al-Zn-Mg-Ca-Fe铝合金

摘要

根据其结构，技术和机械性能的研究，证实了未经热处理的高强度铝－锌－镁－钙－铁铸造合金的成分和应用前景。作为研究对象，我们获得了一种合金，该合金基于Al–5.5％Zn–1.5％Mg（wt％）的成分，分别与0.5–1.0％Ca和0.5％Fe合金化。作为参考，我们使用对应于GOST（国家标准）1583-93的标准AK12M2，AMg6lch和AM4.5Kd铸造合金：通过铅笔样品铸造，已经测试了该合金由于阻碍收缩而形成热裂纹的趋势。已经表明，与钙和铁分开合金化不会促进抗裂性的任何改善，并且不利地影响机械性能。与1％Ca和0.5％Fe的组合合金化可以将热撕裂敏感性参数提高到AMg6lch合金固有的水平。该作用是由于形成共晶含钙相以及形成没有柱状晶粒的良好晶粒结构而引起的。合金结构中的铁结合在致密颗粒中，代表Al ₁₀ CaFe ₂阶段，这是在冷模铸造过程中发生的非平衡结晶过程的结果。该相的形成使得有可能减少（Al，Zn）₄ Ca相中的锌含量，并主要保留（Al）固溶体的成分，这与基础Al– 5.5％锌–1.5％镁合金和铝–5.5％锌–1.5％镁–1％钙–0.5％–铁合金，以及这些值优于分别与钙和铁合金化的合金的硬度值。另外，在相同状态下，有希望的合金在铸造状态下的硬度比品牌铸造合金的硬度高20 HV以上。处于铸造状态的新型合金显示出以下竞争性的机械拉伸性能：_σUTS〜310兆帕，σ _0.2〜210兆帕，δ〜4％。