Achievement of High Ductility and Ultra-high Strength of V-Nb Microalloyed Spring Steel by Austempered Multiphase Microstructure. - Chen, Kui; Jiang, Zhouhua; Liu, Fubin; Li, Huabing; Kang, Congpeng; Zhang, Wenchao; Wang, Ao (Metallurgical & Materials Transactions. Part A, 2020)