Unveiling Interactions of Non-Metallic Inclusions within Advanced Ultra-High Strength Steel: A Spectro-Microscopic Determination and First-Principles Elucidation

Harishchandra Singh,Alexei Zakharov,Marko Huttula,Wei Cao,Tuomas Alatarvas,Shubo Wang,Assa Sasikaladevi,Frank M F De Groot,Brice Sarpi,Yuran Niu,Andrey A Kistanov ,Tapio Fabritius

doi:10.2139/ssrn.3757898

Abstract

Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. Herein, advanced Synchrotron X-ray absorption coupled with photoemission electron microscopy and first-principles calculations are employed to provide the structure, local bonding structure and electronic properties of several NMI model systems and their interaction mechanism within and the steel matrix. B K-, N K-, Ca L2,3- and Ti L2,3-edge spectra show that the additional B prefers to result in h-BN exhibiting strong interaction with Ca2+. Such Ca2+-based phases also stabilize though TiN, revealing the irregular coordination of Ca2+. Observed intriguing no interaction between TiN and h-BN is further supported with the first-principles calculations, wherein unfavorable combination of TiN and h-BN and stabilization of bigger sized Ca2+-based inclusions have been found. These observations can help to optimize the interaction mechanism among various inclusions as well as steel matrix.

Highlights

Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques
NMIs are regions of non-metallic chemical compounds, e.g., Al2O3, SiO2, MgAl2O4, MnS, CaS, and AlN, BN, TiN within a steel matrix that are formed through various physical effects during the different stages of steel production
(DFT) calculations is a powerful supporting tool, for instance, joint experimental and DFT study revealed the effect of various inclusions on the performance of steel [10–13], indicating its potential when coupled with advanced spectro-microscopy (X-PEEM)

Summary

Introduction

Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. On comparing the XAS spectra including their tiny features with the reported Ti-based compounds, the results indicate that in the present case, A1 and A3 inclusions show the characteristics of TiN [21,22], which is further confirmed with N K-edge XAS data discussed below.

Results

Conclusion