*Article* **Microstructure and Mechanical Properties of Tempered Ausrolled Nanobainite Steel**

#### **Jing Zhao 1, Dezheng Liu 1,\*, Yan Li 1, Yongsheng Yang 2,\*, Tiansheng Wang 3 and Qian Zhou 4**


Received: 8 June 2020; Accepted: 1 July 2020; Published: 3 July 2020

**Abstract:** The microstructures and mechanical properties of ausrolled nanobainite steel, after being tempered at temperatures in the range of 200−400 ◦C, were investigated in this study. After being tempered, bainitic ferrite is coarsened and the volume fraction of retained austenite is reduced. The hardness and ultimate tensile strength decrease sharply. The impact energy, yield strength, and elongation increase with elevated tempered temperature at 200–300 ◦C but decrease with elevated tempered temperature when the samples are tempered at 350 ◦C and 400 ◦C. The fracture appearance of all the samples after impact tests is a brittle fracture. The variation of the mechanical properties may be due to partial recovery and recrystallization.

**Keywords:** tempered; ausrolled nanobainite; microstructures; mechanical properties
