A method of setting air-gap thermal resistance at the bottom of cooling mold was proposed to improve the homogeneity of circumferential microstructure and mechanical properties of BFe10-1-1 cupronickel tube produced by heating-cooling combined mold (HCCM) horizontal continuous casting. The influences of thermal-resistance angle on the heat transfer during continuous casting, circumferential microstructure and mechanical properties of the tube were investigated. The results show that for non-thermal resistance, the tube mainly consists of“V”type columnar grains at both the upper and lower parts, and axial columnar grains whose growth direction has an angle of 29°-36° to the axial direction at the lateral part. The morphology and number of the columnar grains at circumference of the tube are inhomogeneous, which induces apparent inhomogeneity of the tensile strength and elongation to failure of the tube. For the thermal-resistance angle of 8°-32°, with increasing the thermal-resistance angle, the angle between the columnar grain and the axial direction decreases, and the homogeneity of circumferential microstructure and mechanical properties of the tube is improved. The appropriate thermal-resistance angle at the bottom of cooling mold for BFe10-1-1 cupronickel tube is 32°. Setting air-gap thermal resistance at the bottom of cooling mold improves the homogeneity of both circumferential heat transfer and temperature filed in the solidified zone of the tube during HCCM horizontal continuous casting, which is mainly responsible for enhancing the homogeneity of microstructure and mechanical properties of BFe10-1-1 cupronickel tube.%提出在结晶器冷型底部设置气隙热阻以提高热冷组合铸型(HCCM)水平连铸 BFe10-1-1管材周向组织和力学性能均匀性的方法，研究热阻角对连铸传热行为、管材周向组织和力学性能均匀性的影响。结果表明：未设置热阻时，管材上部和下部组织均由“V”形柱状晶组成，侧部组织为与轴向呈夹角29°~36°的柱状晶，周向的柱状晶形貌和数量分布不均匀，其周向不同部位的抗拉强度和断后伸长率差异较大。当热阻角为8°~32°时，随热阻角的增大，管材柱状晶组织与轴向的夹角减小，周向组织和力学性能的均匀性提高。在本实验条件下，BFe10-1-1管材HCCM水平连铸结晶器冷型底部设置合理的热阻角为32°。冷型底部设置热阻使管材周向传热及凝固区周向温度场分布更为均匀，这是管材周向组织和力学性能均匀性提高的主要原因。
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