Ce改善含铜砷钢高温氧化与热裂行为研究

Effect of Ce on the High Temperature Oxidation and Hot Cracking Behavior of Copper-arsenic Steel

利用热重法、光学显微镜(OM)、扫描电镜(SEM)和Gleeble-3800热/力模拟试验机研究了Ce含量对含铜砷钢高温氧化性的影响规律及其改善钢热裂的效果。氧化动力学及氧化层形貌分析表明,950℃~1050℃氧化时实验钢遵循氧化初期直线段氧化完后抛物线的氧化规律,1100℃与1150℃由于氧化层分离为双直线段氧化规律。随着Ce含量增加,氧化增重量逐渐减少,氧化激活能增加,氧化膜晶粒细化,含铜砷钢抗氧化性增强。元素面扫描及模拟热压缩实验分析表明,不含Ce的实验钢1050℃下氧化时铜砷富集量最多且有沿晶界浸润的富铜砷相,其热裂也最为严重;而随Ce含量的增加有效减少氧化层与基体界面处的铜砷富集并改善含铜砷钢热裂。氧化激活能增加、Fe_(2)SiO_(4)层和含砷稀土夹杂物的形成是稀土Ce改善含铜砷钢高温氧化与热裂性的原因。

The effect of Ce content on high temperature oxidation of steel containing copper-arsenic and the inhibition of hot cracking was investigated by thermogravimetry, optical microscope(OM), scanning electron microscope(SEM) and Gleeble-3800 thermal/mechanical simulation machine. The oxidation kinetics analysis and oxide scale morphology observation shows that the oxidation weight gain gradually decreases with the increase of Ce content.Furthermore, oxidation kinetics follows the initial linear oxidation law and the later parabolic oxidation law at 950 to 1050 ℃, while oxidation kinetics obeys linear oxidation law of two stages at 1100 ℃ and 1150 ℃. The oxidation activation energy increases as increasing Ce content, which results in the oxidation resistance improvement of steel. The results of element mapping distribution and hot compression test indicates that the copper-arsenic enrichment degree of the steel without Ce is maximum at 1050 ℃ along with the penetration of copper-arsenic enriched liquid phase into the grain boundary, and meanwhile the hot cracking is the most serious. However, the copper-arsenic enrichment at the scale/steel matrix interface effectively is reduced and the hot cracking of steel caused by copper-arsenic enriched liquid phase is suppressed with the increase of Ce content. The increase of oxidation activation energy, the formation of Fe_(2)SiO_(4) layer and arsenic-containing rare-earth inclusions are the reasons of the improvement of hot cracking of steel containing copper-arsenic by rare-earth Ce.