材料期刊网

通过腐蚀磨损实验研究了下贝氏体球墨铸铁材料的腐蚀磨粒磨损行为,分析了影响腐蚀磨损失重率的主要因素.采用SEM和TEM对磨损表面特性进行了分析,根据磨损表层纵剖面的显微硬度研究了材料表层在腐蚀磨损过程中的形变硬化效应,结合下贝氏体球墨铸铁的电化学行为研究了载荷对耐腐蚀性能的影响.结果表明,下贝氏体球墨铸铁的腐蚀磨损机理为化学腐蚀失重和犁沟式磨粒磨损.载荷的提高对表面粗糙度、材料表面与磨粒之间的摩擦力以及磨粒压入材料表面的深度有显著的影响,从而导致磨粒磨损失重率显著上升.较高的载荷作用下,材料表面出现分层组织和条带状石墨,形成局部微型原电池,促使腐蚀速率提高,同时分层组织的疲劳断裂也将促使失重率进一步提升.载荷的增加使得基体中残留奥氏体内部出现大量位错的缠结,促进材料表面硬化,在一定程度上提高了材料的耐磨性能.当载荷从10N增至200N时,腐蚀磨损失重率从0.16 g/(cm2·h)增至0.42 g/(cm2·h).当粗糙度Rs由0.12 μm增大到5.20μm时,腐蚀电流密度从0.56 mA/cm2上升至5.62 mA/cm2.下贝氏体球墨铸铁的腐蚀磨损失重曲线可分为3个阶段,分别为磨损初期的点接触加速磨损阶段、磨损中期的面接触过渡磨损阶段、磨损后期的疲劳磨损阶段.

The corrosion-abrasive wear behavior of lower bainite ductile iron was investigated by corrosionabrasive wear tests.The main factors of mass loss rate were analyzed.SEM and TEM were used to observe the wom surfaces.The strain-hardening effects beneath the contact surfaces were analyzed by microhardness profiles.The influence of load to corrosion resistance was researched by polarization curves.The results show that the main corrosion wear mechanism was corrosion mass loss and furrow wear.The roughness of worn surface,friction between sample and abrasive,depth of furrow all increased with the test load,which increased the corrosion-abrasive wear rate sharply.Meanwhile,the corrosion micro-cell formed along with the appearance of graphite ribbon and delamination at a higher load,which enhanced the corrosion rate rapidly,and the fracture of delamination resulting from plastic deformation fatigue was another critical factor of the increased mass loss.With the increase of test load,dislocation multiplication and pile-up took place in the retained austenite,which improved the wear resistance of material to some extent.However,the improvement was limited.The average mass loss rate was still increased from 0.16 g/(cm2· h) to 0.42 g/(cm2· h) with the increase of test load; the corrosion current density (icorr) was enhanced from 0.56 mA/cm2 to 5.62 mA/cm2 along with the increase of roughness.In addition,the mass loss curves of lower bainite ductile iron were divided into three stages:point contact wear (initial stage),surface contact wear (transition stage) and fatigue wear (stability stage).