摘要
利用25 kg真空冶炼炉和550 mm热轧实验机组制备了一种新型1.5 GPa超高强度钢板,采用Formastor-F相变仪、光学显微镜(OM)、透射电镜(TEM)等研究了镧对1.5 GPa超高强度钢的淬透性及微观组织的影响。结果表明:当冷却速率达到10℃/s以上时,实验钢组织中出现马氏体。与不加镧的实验钢相比较,加入0.09%的镧降低了1.5 GPa超高强度钢的临界冷却速率60%以上。镧促进了实验钢马氏体的转变,显著提高了其淬透性,主要原因是镧原子偏聚抑制了奥氏体扩散型分解并促进了马氏体非扩散型切变。镧在实验钢中通过原子偏聚影响微结构,一部分镧原子向晶界偏聚,另一部分向异质形核质点偏聚。
A new type of 1.5 GPa ultrahigh strength steel plate was prepared by using 25 kg vacuum smelting furnace and 550 mm hot rolling mill. The effects of lanthanum on hardenability and microstructure of the 1.5 GPa ultrahigh strength steel were studied by means of Formastor-F phase transformation tester, optical microscope(OM) and transmission electron microscopy(TEM). The results show that the martensite appears in the microstructure of the experimental steel when the cooling rate reaches more than 10 ℃/s. Compared with the experimental steel without lanthanum, adding 0.09% lanthanum reduces the critical cooling rate of the 1.5 GPa ultrahigh strength steel by more than 60%. lanthanum promotes the transformation of martensite in the experimental steel and significantly improves its hardenability, the main reason is that the segregation of lanthanum atoms inhibits the diffusion decomposition of austenite and promotes the non-diffusion shear of martensite. The microstructure of the experimental steel is affected by the atomic segregation of lanthanum, one part of lanthanum atoms segregate at the grain boundary and the other part segregate at heteromorphic nuclei.
作者
高志国
GAO Zhi-guo(College of Mechanical and Electrical Engineering,Wuyi University,Wuyishan 354300,China;Technology Center,Inner Mongolia Baogang Steel Union Co Ltd,Baotou 014010,China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2020年第11期103-109,共7页
Transactions of Materials and Heat Treatment
基金
包头市重大科技发展项目(2013Z1001)。
关键词
稀土镧
冷却速率
微观组织
淬透性
超高强度钢
rare earth lanthanum
cooling rate
microstructure
hardenability
ultrahigh strength steel
