**E**ff**ect of Intercritical Annealing and Austempering on the Microstructure and Mechanical Properties of a High Silicon Manganese Steel**

**Mattia Franceschi 1,\*, Luca Pezzato <sup>1</sup> , Claudio Gennari <sup>1</sup> , Alberto Fabrizi <sup>2</sup> , Marina Polyakova <sup>3</sup> , Dmitry Konstantinov <sup>3</sup> , Katya Brunelli <sup>1</sup> and Manuele Dabalà 1**


Received: 29 September 2020; Accepted: 27 October 2020; Published: 29 October 2020

**Abstract:** High Silicon Austempered steels (AHSS) are materials of great interest due to their excellent combination of high strength, ductility, toughness, and limited costs. These steel grades are characterized by a microstructure consisting of ferrite and bainite, accompanied by a high quantity retained austenite (RA). The aim of this study is to analyze the effect of an innovative heat treatment, consisting of intercritical annealing at 780 ◦C and austempering at 400 ◦C for 30 minutes, on the microstructure and mechanical properties of a novel high silicon steel (0.43C-3.26Si-2.72Mn wt.%). The microstructure was characterized by optical and electron microscopy and XRD analysis. Hardness and tensile tests were performed. A multiphase ferritic-martensitic microstructure was obtained. A hardness of 426 HV and a tensile strength of 1650 MPa were measured, with an elongation of 4.5%. The results were compared with those ones obtained with annealing and Q&T treatments.

**Keywords:** austempering; high silicon steel; retained austenite; mechanical properties
