UNS N08810镍基合金因其优异的高温耐腐蚀性能,被广泛应用于核反应堆热交换器等关键部件。然而,传统轧制工艺在制备小规格棒材时易出现组织不均和表面裂纹等问题。本研究采用热挤压工艺,创新性地采用了三向压应力的热加工方式,探究了不...UNS N08810镍基合金因其优异的高温耐腐蚀性能,被广泛应用于核反应堆热交换器等关键部件。然而,传统轧制工艺在制备小规格棒材时易出现组织不均和表面裂纹等问题。本研究采用热挤压工艺,创新性地采用了三向压应力的热加工方式,探究了不同挤压温度(1120~1240℃)对ϕ90 mm UNS N08810合金棒材成形能力、晶粒组织及力学性能的影响。实验发现:当挤压温度低于1160℃时,材料因变形抗力过大导致“闷车”(即材料无法挤出);温度高于1200℃时,棒材头部因局部晶粒粗化出现开裂;而1160~1200℃为最佳成形区间,其中1163℃挤压的棒材晶粒度均匀(5.0~5.5级),室温拉伸性能(抗拉强度561 MPa,延伸率52%)完全满足核电标准(ASTM A312/A312M)。此外,高温拉伸测试表明,随着温度从500℃升至900℃,材料强度逐渐下降而延展性提升,但不同挤压温度下的高温性能差异不显著。最终通过数据拟合确定核电用棒材的优化挤压温度为(1160±10)℃,兼顾成形效率与组织均匀性。本研究为核电高温合金的精密加工提供了重要工艺参考,同时揭示了热挤压温度对材料性能的调控机制,对提升核能装备可靠性具有实际意义。展开更多
采用反向热挤压技术,制备了外径39.5 mm、壁厚4.5 mm的Nd-Fe-B磁环,研究了挤压速度、变形压力和模具结构对反向热挤压Nd-Fe-B磁环磁性能、微观组织和相结构的影响,结果表明,随着挤压速度、变形压力的提高,磁环的磁性能先增大后减小,挤...采用反向热挤压技术,制备了外径39.5 mm、壁厚4.5 mm的Nd-Fe-B磁环,研究了挤压速度、变形压力和模具结构对反向热挤压Nd-Fe-B磁环磁性能、微观组织和相结构的影响,结果表明,随着挤压速度、变形压力的提高,磁环的磁性能先增大后减小,挤压速度0.05 mm/s、变形压力164 MPa下制备的磁环磁性能最佳,剩磁、矫顽力和最大磁能积分别为12.385 kGs、10.705 kOe、32.808 MGOe。采用具有凸台结构的反向热挤压模具制备的Nd-Fe-B永磁环比常规的反向热挤压模具制备的磁环的矫顽力更高且磁性能轴向均匀性更好。Nd-Fe-B magnetic ring with outer diameter of 39.5 mm and wall thickness of 4.5 mm was prepared by backward hot-extrusion technology. The effects of extrusion speed, deformation pressure and mold structure on the magnetic properties, microstructure and phase structure of the backward hot-extruded Nd-Fe-B magnetic ring were studied. The results showed that, with the increase of extrusion speed and deformation stress, the magnetic properties of the magnetic ring increased first and then decreased. The magnetic properties of the magnetic ring prepared using an extrusion speed of 0.05 mm/s and a deformation pressure of 164 MPa were the best, and its remanence, coercivity and maximum magnetic energy product were 12.385 kGs, 10.705 kOe and 32.808 MGOe, respectively. The Nd-Fe-B permanent magnet prepared by the backward hot-extrusion mold with a boss structure has higher coercivity and better axial uniformity of magnetic properties than the magnetic ring prepared by the conventional backward hot-extrusion mold.展开更多
文摘UNS N08810镍基合金因其优异的高温耐腐蚀性能,被广泛应用于核反应堆热交换器等关键部件。然而,传统轧制工艺在制备小规格棒材时易出现组织不均和表面裂纹等问题。本研究采用热挤压工艺,创新性地采用了三向压应力的热加工方式,探究了不同挤压温度(1120~1240℃)对ϕ90 mm UNS N08810合金棒材成形能力、晶粒组织及力学性能的影响。实验发现:当挤压温度低于1160℃时,材料因变形抗力过大导致“闷车”(即材料无法挤出);温度高于1200℃时,棒材头部因局部晶粒粗化出现开裂;而1160~1200℃为最佳成形区间,其中1163℃挤压的棒材晶粒度均匀(5.0~5.5级),室温拉伸性能(抗拉强度561 MPa,延伸率52%)完全满足核电标准(ASTM A312/A312M)。此外,高温拉伸测试表明,随着温度从500℃升至900℃,材料强度逐渐下降而延展性提升,但不同挤压温度下的高温性能差异不显著。最终通过数据拟合确定核电用棒材的优化挤压温度为(1160±10)℃,兼顾成形效率与组织均匀性。本研究为核电高温合金的精密加工提供了重要工艺参考,同时揭示了热挤压温度对材料性能的调控机制,对提升核能装备可靠性具有实际意义。
文摘采用反向热挤压技术,制备了外径39.5 mm、壁厚4.5 mm的Nd-Fe-B磁环,研究了挤压速度、变形压力和模具结构对反向热挤压Nd-Fe-B磁环磁性能、微观组织和相结构的影响,结果表明,随着挤压速度、变形压力的提高,磁环的磁性能先增大后减小,挤压速度0.05 mm/s、变形压力164 MPa下制备的磁环磁性能最佳,剩磁、矫顽力和最大磁能积分别为12.385 kGs、10.705 kOe、32.808 MGOe。采用具有凸台结构的反向热挤压模具制备的Nd-Fe-B永磁环比常规的反向热挤压模具制备的磁环的矫顽力更高且磁性能轴向均匀性更好。Nd-Fe-B magnetic ring with outer diameter of 39.5 mm and wall thickness of 4.5 mm was prepared by backward hot-extrusion technology. The effects of extrusion speed, deformation pressure and mold structure on the magnetic properties, microstructure and phase structure of the backward hot-extruded Nd-Fe-B magnetic ring were studied. The results showed that, with the increase of extrusion speed and deformation stress, the magnetic properties of the magnetic ring increased first and then decreased. The magnetic properties of the magnetic ring prepared using an extrusion speed of 0.05 mm/s and a deformation pressure of 164 MPa were the best, and its remanence, coercivity and maximum magnetic energy product were 12.385 kGs, 10.705 kOe and 32.808 MGOe, respectively. The Nd-Fe-B permanent magnet prepared by the backward hot-extrusion mold with a boss structure has higher coercivity and better axial uniformity of magnetic properties than the magnetic ring prepared by the conventional backward hot-extrusion mold.
