碳钢表面腐蚀沟槽的形成原因  

Reason for Formation of Corrosive Ditch of Carbon Steels

作　　者：王小燕[1] 杨峥[1] 方政[1] 方金凤[1] 

机构地区：[1]马鞍山钢铁股份有限公司技术中心,安徽马鞍山243000

出　　处：《全面腐蚀控制》2010年第2期8-12,共5页Total Corrosion Control

摘　　要：利用金相显微镜和电子探针分析了扩散退火前后碳钢的金相组织、夹杂物和磷偏析的变化情况。通过模拟闭塞腐蚀电池试验研究了钢在热处理前后的点蚀扩展速度,并利用电子探针和扫描电镜分析了钢表面的蚀坑形貌。综合分析了碳钢表面出现腐蚀沟槽的原因。结果表明,扩散退火处理可以消除钢中的带状组织,但不能消除钢中的磷偏析。在蚀孔酸化的条件下,磷偏析的低磷微区的腐蚀速度大于高磷微区,从而在腐蚀形貌上出现腐蚀沟槽。此外,低磷微区的快速腐蚀会导致钢蚀坑扩展速度的加快。The microstructures, inclusions and of steels before and after diffusion annealing was compared by means of microscope and electron probe micro-analyzer （EPMA）. The pitting propagation rate was evaluated by simulating occluded corrosion cell （SOCC）, and corrosive characteristic of pits was studied by scanning electro microscopy （SEM） and EPMA. The reason for formation of corrosive ditch was therefore analyzed synthetically. The results indicate that diffusion annealing can eliminate banded structure, but not remove phosphoric segregation. Under the acidification condition in pits, the low-phosphorus area phosphoric segregation exhibit greater corrosion rate than the high-phosphorus area. Additionally, fast corrosion of low-phosphorus area will accelerate the pit propagation rate of steel.

关 键 词：磷偏析点蚀 腐蚀 沟槽 

分 类 号：TG172.5[金属学及工艺—金属表面处理]