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Technology and market study on continuous casting rolls
2006 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This Master’s Thesis consists of two separate and independent studies: One metallurgical study and one industrial buying behaviour study. Both studies concern continuous casting rolls. Metallurgical Study: The first objective of this study was to investigate two continuous casting rolls, consisting of different steel tubes with different martensitic stainless steel weld overlays. The second objective was to evaluate the methods employed in the study. The weld overlaps are clearly the weakest points of the weld overlay. They are sensitive to corrosion attacks, mainly due to sensitisation. The delta ferrite present in the welded overlay of both rolls is a preferential site for the corrosion attacks and the delta ferrite content depends primarily on the chemical composition of the weld overlay. The welding temperature may also have some influence on the delta ferrite content, but this has not been observed in this study. Both rolls have similar surface hardness. Roll no. 2 has more generalized corrosion attacks than roll no. 1. This is due to a higher delta ferrite content in roll no. 2 than in roll no. 1. The methods employed during the study proved to be adequate. In any future study, on condition that the visual inspection, diameter measurements, ultrasonic testing and surface hardness measurements show that all positions on the roll are similar, it will be sufficient to cut a bead and overlap sample from only one position. The rolls were investigated using macro etching, optical microscopy, Vickers hardness testing, ultrasonic testing ICP-OES analysis of nickel and chromium content and carbon content analysis by wet chemical method. Delta ferrite content was also calculated theoretically using a Schaeffler – DeLong diagram and a semi-empirical model. Industrial Buying Behaviour Study: The aim of this study is to investigate the industrial buying behaviour in slab casting steelworks in Western Europe when buying roll-lines. Case studies have been conducted at four steelworks belonging to different companies. Data was collected through personal interviews with people from production, maintenance and purchasing department and intermediate level management. A test consisting of a smaller amount of rolls is always performed before buying any larger quantities of rolls. Even though the test order has relatively low economic value, compared to a full-scale order, it is during this process that the relationships are established between the buying and the selling company. Findings show that the industrial buying behaviour of steelworks in Western Europe agrees well with the theory in this field. The buying process follows the steps in the buygrid model with only a few exceptions. The decision-making power lays in the intermediate level management, even though approval is required from upper level management. The most important factors affecting the buying behaviour are the relationship between the buyer and the seller, service-life and life cycle cost of the roll-line.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Continuous Casting Rolls, Steel, Submerged Arc Welding, Metallurgy, Industrial Buying Behaviour, Steelworks, Stränggjutningsrullar, Påläggssvetsning, Köpbeteende, Stålverk
Keyword [sv]
URN: urn:nbn:se:ltu:diva-56164ISRN: LTU-EX--06/258--SELocal ID: cf3d992b-9025-4779-9168-c46d3822691aOAI: diva2:1029551
Subject / course
Student thesis, at least 30 credits
Educational program
Materials Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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