Li Zhao, Wu Run, Li Mingwei, Zeng Song-Sheng, Wang Yu, Xie Tian, Wu Teng
Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China.
Valin ArcelorMittal Automotive Steel Co., Ltd., Loudi 417009, China.
Materials (Basel). 2021 Mar 22;14(6):1556. doi: 10.3390/ma14061556.
High boron steel is prone to brittle failure due to the boride distributed in it with net-like or fishbone morphology, which limit its applications. The Quenching and Partitioning (Q&P) heat treatment is a promising process to produce martensitic steel with excellent mechanical properties, especially high toughness by increasing the volume fraction of retained austensite (RA) in the martensitic matrix. In this work, the Q&P heat treatment is used to improve the inherent defect of insufficient toughness of high boron steel, and the effect mechanism of this process on microstructure transformation and the change of mechanical properties of the steel has also been investigated. The high boron steel as-casted is composed of martensite, retained austensite (RA) and eutectic borides. A proper quenching and partitioning heat treatment leads to a significant change of the microstructure and mechanical properties of the steel. The net-like and fishbone-like boride is partially broken and spheroidized. The volume fraction of RA increases from 10% in the as-cast condition to 19%, and its morphology also changes from blocky to film-like. Although the macro-hardness has slightly reduced, the toughness is significantly increased up to 7.5 J·cm, and the wear resistance is also improved.
高硼钢由于其中分布着网状或鱼骨状的硼化物而易于发生脆性破坏，这限制了其应用。淬火配分（Q&P）热处理是一种很有前景的工艺，可通过增加马氏体基体中残余奥氏体（RA）的体积分数来生产具有优异力学性能，特别是高韧性的马氏体钢。在这项工作中，采用Q&P热处理来改善高硼钢韧性不足的固有缺陷，并研究了该工艺对钢的微观结构转变及力学性能变化的影响机制。铸态高硼钢由马氏体、残余奥氏体（RA）和共晶硼化物组成。适当的淬火配分热处理会导致钢的微观结构和力学性能发生显著变化。网状和鱼骨状硼化物部分破碎并球化。RA的体积分数从铸态时的10%增加到19%，其形态也从块状变为薄膜状。尽管宏观硬度略有降低，但韧性显著提高至7.5 J·cm，耐磨性也得到改善。
