乙烯裂解炉管运行失效研究及焊接修复  

Study of ethylene cracking furnace tube operational failure after service and welding repair

作　　者：张元杰[1,2] 彭云[2] 张晓牧[2] 马成勇[2] 田志凌[2] 陆建生[1] 

机构地区：[1]昆明理工大学材料科学与工程学院,昆明650093 [2]钢铁研究总院,北京100081

出　　处：《材料科学与工艺》2013年第3期55-62,共8页Materials Science and Technology

摘　　要：乙烯裂解炉管由于服役环境恶劣,长时间运行后容易产生破损需要进行修复,但在焊接修复时极易开裂,为了找出其易开裂的原因,本文用扫描电镜和金相显微镜观察分析了HP40Nb乙烯裂解炉管服役前后的组织性能变化,并通过热力学计算对试验结果进行分析,找出了焊接性能恶化的原因,并制定热处理工艺改善其焊接性.结果表明:长时间服役后,炉管析出相为M23C6、M7C3和MC相,析出相严重长大粗化,沿晶界呈链状分布,使材料塑性几乎为0,这是导致焊接易开裂的主要原因;通过热处理改善碳化物的分布形态,可以有效提高旧管的塑性和焊接性;通过热力学计算得出,当基体中固溶的Cr质量分数大于10%时,为M23C6的析出过程,基体固溶的Cr质量分数小于10%时,为M7C3的析出过程.Damage always occurs on ethylene cracking furnace tube under critical operation conditions and the tube needs welding repair.To find out the reason for welding failure of long-term served ethylene cracking furnace tube,the microstructure and performance evolution of the tube after service was investigated by metallographic observation and thermodynamics calculation.Main influencing factors of furnace tubes was analyzed and reasonable heat-treating process was made to improve the weld ability.The results show that the precipitated phases are M23C6、M7C3 and little MC after long-term served and the density of the precipitates in the matrix becomes higher and the size becomes larger.The precipitated phases distribute as chain-like along grain boundaries is the main reason for welding failure because it decreases plasticity seriously.By heat treatment the carbides morphology is changed,and the plastic deformation of old tube improves significantly.Based on the thermodynamic calculation result,when the Cr solution content is more than 10% in matrix,the precipitation process is M23C6 precipitates,and when it is less than 10%,the precipitation process is M7C3 precipitates.

关 键 词：乙烯裂解炉 显微组织 析出相 热处理 焊接 

分 类 号：TG142.3[一般工业技术—材料科学与工程]