铸造TiAl合金凝固组织的截面尺寸效应

发布时间：2018-01-31 11:07

本文关键词： 铸造TiAl合金尺寸效应柱状晶生长方向柱状晶宽度　出处：《稀有金属》2017年07期 　论文类型：期刊论文

【摘要】：采用数值计算和试验的方法,研究了直径30~50 mm Ti Al合金铸锭凝固组织的截面尺寸效应。结果表明:受径向散热和轴向散热竞争的影响,Ti Al合金铸锭的宏观组织存在竞争生长区、径向生长区和冒口影响区,随铸锭高径比增大,竞争生长区和冒口影响区占比减小,径向生长区占比增大。在径向生长区内,对于同一Ti Al合金铸锭,随散热距离的增加,柱状晶宽度增大,但增大的幅度逐渐减小;对于不同直径的Ti Al合金铸锭,在相同散热距离处,较大直径铸锭的柱状晶宽度更宽,且不同直径铸锭柱状晶宽度的差值随径向散热距离的增加而增大。通过拟合径向温度梯度和轴向温度梯度与铸锭直径和轴向散热距离的关系,建立了柱状晶生长方向与铸锭直径和轴向散热距离的关系。通过拟合温度梯度和凝固速率与铸锭直径和径向散热距离的关系,并耦合柱状晶宽度与温度梯度和凝固速率的关系,建立了柱状晶宽度与铸锭直径和径向散热距离的关系。
[Abstract]:The section size effect of solidified microstructure of 30 ~ 50mm Ti Al alloy ingot is studied by numerical calculation and experiment. The results show that the effect of radial heat dissipation and axial heat dissipation is affected. There are competitive growth zone, radial growth zone and riser influence zone in the microstructure of Ti-Al alloy ingot. With the increase of the ratio of height to diameter, the proportion of competitive growth zone and riser influence zone decreases. In the radial growth zone, the width of columnar crystal increases with the increase of heat dissipation distance, but the amplitude of increase decreases gradually for the same Ti-Al alloy ingot. For Ti Al alloy ingot with different diameters, the columnar crystal width of large diameter ingot is wider at the same heat dissipation distance. And the difference between the width of columnar crystal of ingot with different diameters increases with the increase of radial heat dissipation distance. The relationship between radial temperature gradient and axial temperature gradient and the diameter of ingot and the axial heat dissipation distance is fitted by fitting the relationship between radial temperature gradient and axial temperature gradient. The relationship between the growth direction of the columnar crystal and the diameter of the ingot and the axial heat dissipation distance was established, and the relationship between the temperature gradient and the solidification rate and the diameter and radial heat dissipation distance of the ingot was fitted by fitting the temperature gradient and the solidification rate. The relationship between the width of columnar crystal and the temperature gradient and solidification rate was coupled, and the relationship between the width of columnar crystal and the diameter of ingot and radial heat dissipation distance was established.
【作者单位】：钢铁研究总院高温合金新材料北京市重点实验室;
【基金】：国家重点基础研究发展计划项目(2011CB605503)资助
【分类号】：TG292
【正文快照】： 由于凝固散热条件的差异,铸件不同厚度部位组织特征通常有所不同,而这种截面尺寸效应会导致铸件使役性能的不确定性。一般地,导热率低、凝固区间窄的合金会表现出较为明显的凝固组织截面尺寸效应。有研究表明,Ti-48Al-2Nb-2Mn合金铸造圆棒直径由9 mm增加到25 mm,平均层片团尺

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