Increasing micro-purity and determining the effects of the production with and without vacuum refining on the qualitative parameters of forged-steel pieces with a high aluminium content

Abstract

The quality production technology for the WNr. 1.8504 steel was developed. The aim of the work was to achieve the required internal micro-purity and determine the effects of different production technologies on the qualitative parameters of forged-steel pieces. Firstly, polygonal ingots weighing 1600 kg were produced, using the metallurgical units, in a controlled-atmosphere induction-melting furnace (IF) without vacuum treatment, and in a vacuum and pressurized induction-melting furnace (VPIM) with vacuum treatment. The ingots were subsequently reshaped by open-die forging into bars with a rectangular cross-section. The effect of the ingot-production technology was evaluated by comparing the forged-steel pieces in terms of their purity, macrostructure and microstructure. Keywords: vacuum, inclusion, aluminium, steel Izvr{en je bil razvoj kakovostne proizvodne tehnologije jekla W.Nr. 1.8504. Namen je bil dose~i`eleno notranjo mikro~isto~o in ugotoviti vpliv razli~nih tehnologij proizvodnje na kvalitativne parametre odkovkov. Najprej so bili izdelani poligonalni kovani ingoti z maso 1600 kg, z uporabo naslednjih metalur{kih agregatov: v indukcijski talilni pe~i s kontrolirano atmosfero (IF) brez vakuumskega rafiniranja in v vakuumski ter indukcijski talilni pe~i (VPIM) s povi{anim tlakom in z vakuumskim rafiniranjem. Nato so bili ingoti s prostim kovanjem preoblikovani v palice s pravokotnim prerezom. Vpliv tehnologije proizvodnje ingotov je bil ocenjen s primerjavo odkovkov z vidika~istosti, makro in mikrostrukture.