The Effect of Nb on the Microstructures and Hardness of Quenching-Partitioning-Tempering Medium Carbon Steels

Abstract:

Nb-free and Nb-bearing medium carbon steels treated by quenching-partitioning-tempering process were investigated. The microstructural observations and hardness were analyzed by optical microscope, transmission electron microscope, X-ray diffraction and hardness test. Results show that when quenched at 210oC and partitioned at 450oC ultra fine-grained microstructures of martensite, retained austenite and carbides are obtained. The Nb-bearing steel has finer martensite lath, more volume fraction of retained austenite and higher hardness compared with that of Nb-free steel. The addition of Nb is responsible for not only the precipitation strengthening but also the more volume fraction of retained austenite during quenching-partitioning-tempering process.

• Periodical: Advanced Materials Research (Volumes 535-537)
• Pages: 549-553
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.535-537.549
• Online since: June 2012
• Authors: Hua Zheng, Kai Ming Wu, Feng Hu, Yang Zheng Zeng
• Keywords: Metal, Microstructure, Nb-Bearing, Quenching-Partitioning-Tempering Process

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