显微缩松对铁素体球墨铸铁低温韧性的影响
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摘要
针对显微缩松是否影响铁素体基球墨铸铁低温韧性的问题,采用改变冒口颈直径的办法对铸锭内显微缩松进行调控。用Axiovert200MAT金相显微镜和MLA 250(FEI Quanta)扫描电子显微镜观察金相组织和显微缩松,用Nano Measurer 1.2软件测量石墨球的个数及直径。结果表明,金属型铸造球墨铸铁时,合适的冒口颈直径可使三角形显微缩松数量减少、尺寸减小,同时促使三角形显微缩松向多边形或蠕虫状转变。对于纯铁素体基球墨铸铁,当球化率与石墨球数量达到一定程度后,显微缩松转变成影响球墨铸铁超低温冲击韧性的关键因素。
Microshrinkage affects the low temperature toughness of ferritic ductile iron. In order to solve the problem,cast iron ingots were cast by using different riser neck diameters in the work. The microstructure and microshrinkage were observed using Axiovert 200 MAT metallographic microscope and MLA 250 FEI Quanta scanning electron microscope; graphite nodule diameter and count were measured by software of Nano measurer 1.2. The results suggest that the suitable diameter of riser neck could reduce the triangle microshrinkage and its size in matrix, and promote the transformation of microshrinkage shape from the triangle to polygon or worm-like. For the pure ferritic ductile iron, the microshrinkage became the key factor affecting the ultra low temperature toughness when the spheroidization rate and graphite nodule count reached a certain level.
Microshrinkage affects the low temperature toughness of ferritic ductile iron. In order to solve the problem,cast iron ingots were cast by using different riser neck diameters in the work. The microstructure and microshrinkage were observed using Axiovert 200 MAT metallographic microscope and MLA 250 FEI Quanta scanning electron microscope; graphite nodule diameter and count were measured by software of Nano measurer 1.2. The results suggest that the suitable diameter of riser neck could reduce the triangle microshrinkage and its size in matrix, and promote the transformation of microshrinkage shape from the triangle to polygon or worm-like. For the pure ferritic ductile iron, the microshrinkage became the key factor affecting the ultra low temperature toughness when the spheroidization rate and graphite nodule count reached a certain level.
引文
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[11]张新宁,曲迎东,李荣德,等.铁素体球墨铸铁低温冲击断裂裂纹形核及扩展机理[J].金属学报,2015,51(11):1333.
[2]陈卫中,邵忠,杨明昊.地铁轨道用铁素体球墨铸铁垫板的开发[J].铸造,2011,60(6):607.
[3]马敬仲,丁建中,尤其光,等.超低温高韧性球墨铸铁QT400-18AL的研究及应用[J].铸造,2012,61(8):864.
[4]马敬仲,丁建中,曾艺成.高速列车转向架轴箱铸件的生产试验[J].现代铸铁,2012(5):15.
[5]苟华强,雷强,涂建平,等.低合金铁素体球墨铸铁的研制[J].铸造,2015,64(4):253.
[6]丁建中,赵金权,丁杰,等.低温铁素体球墨铸铁的生产与研究[J].现代铸铁,2015(2):32.
[7]丁建中,马敬仲,曾艺成,等.低温铁素体球墨铸铁的特性及质量稳定性研究[J].铸造,2015,64(3):193.
[8]李冬琪,徐德民,于海生.高端球墨铸铁件的研制与应用[J].现代铸铁,2015(5):25.
[9]Ostash O P,Dronyuk M M,Andreiko I M,et al. Enhancement of the resistance of cold-resistant high-strength cast irons to brittle fracture[J].Materials Science,1996,32(6):699.
[10]Ostash O P,Kostyk E M,Andreiko I M,et al. Effect of the microstructure on the low-temperature cyclic crack-growth resistance highstrength cast irons[J]. Materials Science,1997,31(1):51.
[11]张新宁,曲迎东,李荣德,等.铁素体球墨铸铁低温冲击断裂裂纹形核及扩展机理[J].金属学报,2015,51(11):1333.