Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第18卷    第3期    总第108期    2008年3月

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文章编号:1004-0609(2008)03-0421-05
铸轧辊表面裂纹的萌生及扩展机理
许志强,张 沛,杜凤山

(燕山大学 机械工程学院,秦皇岛 066004)

摘 要: 对某厂生产中实际使用的铝板铸轧辊辊套进行解剖,采用金相显微镜、扫描电镜及能谱分析等对表面裂纹和试件断口形貌进行观察。采用X射线衍射仪对裂纹中铝的化合物属性进行测量,分析铝液对铸轧辊辊套表面裂纹形成及扩展的影响;采用金相显微镜对辊套表面及内部金属组织进行对比观察,分析高温及复杂应力作用对铸轧辊辊套表面金属组织性能的影响。结果表明:辊套表面裂纹起源于机械加工产生的微缺陷,铝液对铸轧辊表面腐蚀作用很小,但是渗入到裂纹中的铝液凝固氧化后,相当于在辊套表面金属中嵌入高硬度的杂质,在轧制过程中复杂应力作用下将加快裂纹的扩展速度;高温及复杂应力作用对铸轧辊辊套表面金属组织的影响不大。

 

关键字: 铸轧辊辊套;裂纹;热疲劳;腐蚀;组织变性

Mechanism of crack initiation and propagation on
XU Zhi-qiang, ZHANG Pei, DU Feng-shan

College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China

Abstract: An actual shell of the casting roller was dissected for analysis. The cracks and cracked section were examined by metalloscopy and scanning electron microscopy with EDS mapping to investigate the mechanisms of the crack initiation and propagation. The quantify and characteristic of the compounds associated with Fe-Al were identified by X-ray diffractometry. The effect of the molten aluminum on the crack initiation and propagation on the casting roller surface was analyzed. The metal structure characteristics near the roller shell surface were contrasted to that in the shell interior using metalloscope, and the varieties by the action of the complex stresses and high temperature were analyzed. The results indicate that the crack is initiated in the manufactured defects on the roller surface, and the influence of the molten aluminum on corrosion behavior of the surface metal is little, but the molten aluminum may infiltrate into the cracks on the shell surface and becomes solidified and oxidized. The oxide is a kind of harder impurity inserted into the surface metal. The speed of crack propagation is accelerated when the shell surface subjects to the complex stresses in rolling process. The high temperature and the complex stresses have little effect on the microstructure of the roller shell surface.

 

Key words: casting roller shell; crack; heat fatigue; corrosion; structure characteristics

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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