【摘要】 在总结前人热裂纹研究的基础上，提出了热裂纹形成的凝固收缩补偿模型该模型将合金凝固过程按收缩补偿方式分为准液相区、可补缩区、不可补缩区、晶间搭桥区四个阶段．热裂纹形成于不可补缩区，晶间液相收缩产生孔洞，并在进一步收缩过程中扩展为热裂纹利用等径圆柱和等径圆球模型计算出理想状态下柱状晶和等轴晶不可补缩区液相体积分数范围分别为0．31％－93％和0．83％－26％对Al-Cu合金和Al-Si合金不可补缩温度间隔进行了计算，并与合金热裂倾向试验结果进行了比较，证明合金的不可补缩温度间隔越大，合金的热裂倾向越高在走向凝固热裂研究中发现了热裂纹中晶间搭桥的存在，以及裂纹断面上晶间搭桥破断留下的痕迹更多还原

【Abstract】 Based on analysis to previous research on hot cracking of alloys, a hot cracking model formed through solidification contraction and compensation was proposed. In this model, solidification process of alloy was divided to four stages, quasi-liquid phase stage,compensated stage, uncompensated stage and dendritic bridging stage. Hot cracks started in uncompensated stage. The contraction of inter-dendritic liquid caused cavities between dendrites, then the dendritic bridges broken and hot cracks formed. Fraction range of liquid in uncompensated stage is calculated to be 0.83%-26% and 0.31-9.3% for alloys with equiaxial and columnar grains respectively. The temperature range of uncompensated stage for Al-Si and Al-Cu alloys was calculated. Comparison between theoretical calculation and hot cracking experiments showed that hot cracking tendency of alloys increases with the increase of temperature range of uncompensated stage. The dendritic bridges were first discovered in hot cracks of directionally solidified alloys. The tracks caused by dendritic bridges breaking were also discovered on the section of hot cracks.更多还原