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Introduction

Non-metallic inclusions have a substantial effect on material properties. They mainly limit material properties such as thermal and mechanical fatigue as well as deformability at high degrees of deformation but affect also the pitting corrosion potential, surface quality and polish ability of steel.

Objectives and Motivation

  • Selection, production and delivery of electrode material
  • Fundamental investigation of different slag systems
  • Investigation and evaluation of non-metallic inclusions
  • Investigation and evaluation of material properties

Methodology

The usual praxis to improve these material properties are optimized secondary metallurgical treatments and for highest requirements remelting techniques such as Electro-Slag-Remelting (ESR) and Vacuum-Arc-Remelting (VAR). During these special refining steps, especially larger inclusions can be successfully removed.

Electrode material includes a typical content and composition of non-metallic inclusions. During remelted in a laboratory ESR-plant and different slags, optimized types of inclusions shall be achieved. These variations shall be based on thermodynamic calculations to estimate the effect of different slag components in comparison to fundamental investigations of the solidified slags.

 

Results and application

The main investigation method will be the characterisation of non-metallic inclusions by automated P-SEM supported by automated optical measurements. Thereby the chemical composition, size, shape and distribution of the inclusion will be determined in comparison to the situation of the initial electrodes. In parallel the microstructure (phases) and the chemical composition of the slags will be analysed. Once a suitable type and distribution of non-metallic inclusions is achieved, their effect on material properties will be investigated.