时效处理对冷锻Co-Cr-W-Ni-Mo合金组织演变及强韧性影响
Effect of Aging Treatment on Microstructure Evolution and Strength and Ductility of Cold Forged Co-Cr-W-Ni-Mo Alloy
王中琳 1龚志华 2李权 3包汉生3
作者信息
- 1. 内蒙古科技大学材料与冶金学院,内蒙古包头 014010;钢铁研究总院特殊钢研究院,北京 100081
- 2. 内蒙古科技大学材料与冶金学院,内蒙古包头 014010
- 3. 钢铁研究总院特殊钢研究院,北京 100081
- 折叠
摘要
对冷锻Co-Cr-W-Ni-Mo合金进行了 400～900 ℃时效处理,结合扫描电镜、透射电镜、XRD及化学相分析等手段研究了 Co-Cr-W-Ni-Mo合金在时效过程中碳化物、亚结构、hcp相及层错演变,并分析了其变化对强韧性的影响.结果表明:合金经600 ℃时效2 h具有高的强度及硬度、同时保持较好的塑性及韧性,时效后析出M23C6及M6C两种碳化物,M23C6的析出温度范围为600～800 ℃,M6C开始明显析出的温度为700 ℃,碳化物的析出导致强度硬度升高,但900 ℃大量M6C呈网状沿晶界和变形带析出会同时降低强度及塑性.600 ℃时效时fcc相通过形成层错降低能量保持稳定性从而使层错密度增加而提高强度及塑性.hcp相在800 ℃时效后逆转变为fcc相使应变诱导马氏体转变强化效果消失,同时在此温度下发生再结晶导致冷变形组织消失使强度进一步下降,该合金的再结晶形核机制为凸出机制、亚晶界迁移及亚晶合并3种形核机制共同作用.
Abstract
Cold-forged Co-Cr-W-Ni-Mo.alloy was aged at 400-900 ℃.The carbide,substructure,hcp phase and stacking faults evolution of Co-Cr-W-Ni-Mo alloy during aging were studied by SEM,TEM,XRD and chemical phase analysis,and the influence of the changes on strength and toughness were analyzed.The results show that the alloy aged at 600 ℃ for 2 h has high strength and hardness,while maintaining good ductility and toughness.Mf23C6 and M6C carbides are precipitated after aging.The precipitation temperature range of M23C6 is 600-800 ℃,and the precipitation temperature of M6C is 700 ℃.The precipitation of carbides leads to the increase in strength and hardness,but the precipitation of a large number of network M6C along the grain boundaries and deformation bands at 900 ℃ reduces the strength and ductility at the same time.When the alloy is aged at 600 ℃,the fcc phase reduces the energy,so as to keep stability by forming stacking faults,which increases the density of stacking faults and which improves the strength and ductility.The hcp phase reverses to fcc phase after aging at 800 ℃,which makes the strengthening effect of strain-induced martensitic transformation disappear.Meanwhile,recrystallization occurs at this temperature,which leads to the disappearance of cold deformation structure and a further decrease in strength.The recrystallization nucleation mechanism of the alloy is a combination of three nucleation mechanisms,i.e.protrusion.mechanism,subgrain boundary migration and subgrain merging.
关键词
钴基高温合金/时效处理/力学性能/亚结构/层错Key words
cobalt-based superalloy/aging/mechanical property/substructure/stacking faults引用本文复制引用
基金项目
内蒙古自然科学基金(2022MS05039)
内蒙古自治区高等学校青年科技英才支持计划(NJYT23115)
出版年
2024
NETL
NSTL
万方数据