Effect of Al2O3 in Refining Slag on the Cleanliness and Fatigue Property of Ultra-low-carbon Automotive Steel

Shujun Li,Xueyan Du

doi:10.1590/1980-5373-mr-2021-0556

Abstract

The influence of Al2O3 content in refining slag on the cleanliness and fatigue property of ultra-low-carbon (ULC) automotive steel were investigated based on the industrial experiments. The inclusion-adsorption capacity of the refining slag was calculated and the total [O] (T.O) content of ULC automotive steel was measured. The number density, size distribution and morphology of inclusions were analyzed and their effects on the cleanliness and fatigue property of ultra-low-carbon (ULC) automotive steel were investigated. The results showed that as the Al2O3 content in refining slag increased from 19.92% to 39.73%, the inclusion-adsorption capacity of ULC automotive steel decreased from 210.30 down to 57.12, and the fatigue life from 1.4x104 down to 0.9x104 cycles, while the T.O content of steel increased from 12 up to18 ppm and the inclusion number density from 4 up to 9 per mm2.

Highlights

With the rapid development of the automotive industry, methods of improving the quality and performance of steel have attracted significant attention in recent years
The chemical compositions of the slag samples before and after LF refining are listed in Table 1 and Table 2, the chemical compositions of steel samples are listed in Table 3, respectively
The Al2O3 content was controlled by the pre-melted refining slag at different numerical value, the resulting compositions of the refining slag were detailed in Table 2, revealing slight variations in chemical compositions between the five samples except

Summary

Introduction

With the rapid development of the automotive industry, methods of improving the quality and performance of steel have attracted significant attention in recent years. It is a clearly investigation that the non-metallic inclusions are usually the resources affecting the cleanliness and fatigue properties in ULC automotive steel. How to control non-metallic inclusions at the ultralow level is in the pursuit of ULC automotive steel production[3,4]. The investigation of the cleanliness of ULC automotive steel indicated that an appropriate refining slag caused the inclusions to be removed effectively from steel, resulting in the improvement of the cleanliness and the mechanical properties of the steel. Since the slag in the refining process could control and remove inclusions from the molten steel effectively[5], slag systems and models were designed to investigate the influence of the mechanical properties[6,7,8]. When the Al2O3 content in the refining slag increased from 14.71% to 22.3%, the number density of inclusions increased from 5.2 to 6.5 and the largest size of inclusion raised from 7.3 to 8.3 μm in spring steel[13]

Objectives

Results

Discussion

Conclusion