TY - THES

T1 - Changing of scrap handling to increase the net value of Villares Metals

AU - Krapscha, Clemens

N1 - embargoed until 25-06-2019

PY - 2014

Y1 - 2014

N2 - As part of this diploma thesis the processes of two electric arc furnaces were studied in detail. This was done to analyze the main causes of downtime. The reduction of scrap size, higher power levels for the electric arc furnaces and a premelt-concept were checked for profitability. In order to receive all important data, various tests were carried out. Three different sizes of scrap with the same chemical composition were used to test the effect of scrap size distribution on tap to tap time of the electric arc furnaces. Chips were analyzed as scrap with the smallest size and the lowest density. Mainly blocks of pre melts were tested as scrap with the biggest scrap size. Subsequently scrap with a good scrap size distribution was used. To guarantee a fast and safe scrap size reduction, rolling tests with pre melted material were performed. The production of a supermartensitic, stainless steel was investigated in more detail. This steel is produced out of pre melted material. Pre melted scrap allows a reduction of expensive elements beside phosphorus reduction. The impact of phosphorus on material properties was investigated. The target was to change the production by modifying the chemical composition of the material. If a higher content of phosphorus is allowed, pre melts with low phosphorus contents are not necessary. The process would be easier and cheaper. To demonstrate the effect of phosphorus on supermartensitic, stainless steels, tests like tensile tests, charpy impact tests and pitting corrosion were made. The microstructure got analyzed too. To analyze the effect of phosphorus in a supermartensitic, stainless steel, the results were compared.

AB - As part of this diploma thesis the processes of two electric arc furnaces were studied in detail. This was done to analyze the main causes of downtime. The reduction of scrap size, higher power levels for the electric arc furnaces and a premelt-concept were checked for profitability. In order to receive all important data, various tests were carried out. Three different sizes of scrap with the same chemical composition were used to test the effect of scrap size distribution on tap to tap time of the electric arc furnaces. Chips were analyzed as scrap with the smallest size and the lowest density. Mainly blocks of pre melts were tested as scrap with the biggest scrap size. Subsequently scrap with a good scrap size distribution was used. To guarantee a fast and safe scrap size reduction, rolling tests with pre melted material were performed. The production of a supermartensitic, stainless steel was investigated in more detail. This steel is produced out of pre melted material. Pre melted scrap allows a reduction of expensive elements beside phosphorus reduction. The impact of phosphorus on material properties was investigated. The target was to change the production by modifying the chemical composition of the material. If a higher content of phosphorus is allowed, pre melts with low phosphorus contents are not necessary. The process would be easier and cheaper. To demonstrate the effect of phosphorus on supermartensitic, stainless steels, tests like tensile tests, charpy impact tests and pitting corrosion were made. The microstructure got analyzed too. To analyze the effect of phosphorus in a supermartensitic, stainless steel, the results were compared.

KW - Elektrolichtbogenofen

KW - Schrotthandling

KW - supermartensitischer rostfreier Stahl

KW - Stahlschädlinge

KW - Phosphor

KW - Laves-Phase

KW - tap to tap Zeit

KW - Vorschmelzen

KW - Schrottzusammenstellung

KW - Reduzierung von Phosphor

KW - electric arc furnace

KW - scrap handling

KW - supermartensitic stainless steel

KW - tramp elements

KW - phosphorus

KW - Laves-phase

KW - tap to tap time

KW - pre melts

KW - scrap composition

KW - reduction of phosphorus

M3 - Diploma Thesis

ER -