摘要
Q355D角钢是极端严寒条件下输电铁塔的关键材料,对其低温冲击韧性的要求较为严格。采用体视显微镜(SM)、扫描电子显微镜(SEM)、能谱仪(EDS)、光学显微镜(OM)和透射电子显微镜(TEM),对不同化学成分Q355D角钢冲击断裂试样的微观组织和断口形貌进行了分析,阐明了冲击裂纹的萌生和扩展行为。研究结果表明:Q355D角钢化学成分中C、N含量会显著影响其低温韧性,C、N元素含量较高,会造成大块团珠光体组织增多,以及溶入金属材料晶格的间隙溶质增多,导致角钢塑性变差,脆性增加;此外,在C含量较高的试样组织中还存在带状组织,也导致了角钢塑性变差。在冲击不合试样中还发现了Al_(2)O_(3)夹杂物及第二相粒子富集、长大的现象,其导致了试样的脆断。为此,Q355D角钢C质量分数应不超过0.16%,以降低珠光体含量,改善珠光体团簇偏聚的问题;其生产中应精准添加脱氧剂和优化钙处理工艺,避免过量Al残留与氧发生反应生成Al2O3夹杂物;连铸采用数字化电磁搅拌工艺及轻压下工艺,以改善带状组织及中心偏析。采用以上措施后,实现了Q355D角钢的稳定生产。
Q355D angle steel is the key material of transmission tower under extreme cold conditions,and its low temperature impact toughness is strictly required.The microstructure and fracture morphology of Q355D angle steel specimens with different chemical compositions were analyzed by stereomicroscope(SM),scanning electron microscope(SEM),energy dispersive spectrometer(EDS),optical microscope(OM)and transmission electron microscope(TEM).The initiation and propagation behavior of impact cracks were clarified.The results show that the content of carbon and nitrogen in the chemical composition of Q355D angle steel will significantly affect its low temperature toughness.The high content of carbon and nitrogen elements will cause the increase of cluster pearlite structure and the increase of interstitial solute dissolved in the lattice of metal materials,resulting in the deterioration of plasticity and the increase of brittleness of angle steel.In addition,there is also a banded structure in the sample with higher carbon content,which also leads to the deterioration of the plasticity of the angle steel.In the samples with unqualified impact properties,the phenomenon of Al2O3 inclusions and second phase particles enrichment and growth is also found.Due to the above reasons,the brittle fracture of the samples is caused.Therefore,the mass fraction of carbon in Q355D angle steel should not exceed 0.16%to reduce the content of pearlite and improve the segregation of pearlite clusters.In its production,deoxidizer should be accurately added and calcium treatment process should be optimized to avoid excessive aluminum residue reacting with oxygen to form Al_(2)O_(3) inclusions.Continuous casting adopts digital electromagnetic stirring process and soft reduction process to improve banded structure and central segregation.After adopting the above measures,the stable production of Q355D angle steel is realized.
作者
杨洋
李子正
李岩杰
张中华
王晨阳
张大征
YANG Yang;LI Zizheng;LI Yanjie;ZHANG Zhonghua;WANG Chenyang;ZHANG Dazheng(Technical Center,Tangshan Iron and Steel Group Co.,Ltd.,Tangshan 063100,China;Yanshan University,Qinhuangdao 066004,China;University of Science and Technology Liaoning,Anshan 114051,China)
出处
《轧钢》
北大核心
2025年第4期161-168,共8页
Steel Rolling
基金
河北省重大科技支撑计划创新应用场景专项项目(242Q1501Z)。
关键词
Q355D角钢
低温冲击韧性
断口形貌
C含量
晶粒尺寸
夹杂物
带状组织
Q355D angle steel
low-temperature impact toughness
fracture morphology
carbon content
grain size
inclusion
banded structure
作者简介
杨洋(1989-),男,博士,主要从事金属轧制理论与工艺方面的研究;通信作者:李岩杰(1986-),男,硕士,高级工程师,主要从事金属检测分析及工艺研究。
