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Alternatives to pickling: preparation of carbon and low alloyed steel wire rod
Örebro University, Department of Technology.
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A well established method for scale removal on hot rolled wire rod is pickling. To avoid pollution problems, the wire rod can be mechanically descaled. By this method, the removed scale can be recirculated to the blast furnace.

In batch pickling considerable energy is necessary; e.g. for heating of the pickling baths, ventilation of acid fumes and application of lubricant carrier. Energy consumption of the alternative descaling methods has been assessed and compared to pickling

A method was developed to evaluate the remaining scale on mechanically descaled wire rod. Stretching experiments were used to evaluate adhesion of scale to the wire rod surface of different steel grades. Most of the scale was removed on the carbon steel grades and Cr/V alloyed steel grades. More scale remained on silicon alloyed steel grades.

Shot blasting with steel shots was studied as an alternative to pickling. This method removed the scale on all studied steel grades, even the silicon alloyed grades. The wire rod surface was much rougher compared to the pickled wire rod surface. The shot blast power consumption was measured and evaluated. The PC strand wire gave more wear of dies otherwise the shot blasted wire rod showed no difference in the wire drawing process compared to pickled wire rod. Downstream problems such as cleaning and adherence of copper were observed.

Reverse bending and brushing with steel brushes and brushes with SiC abrasives were studied on wire rod of low carbon and silicon chromium alloyed steel grades. Scale remained in surface valleys after brushing of the low carbon steel grade. The silicon steel grades were not possible to descale by bending and brushing. Surface defects from brushing were observed on wire rods brushed by steel brushes, but not on wire rod brushed by SiC-nylon brushes.

A study of shot blasting with recycled glass was done. Due to the lower density, the shot velocity must be higher than for steel shots. Recycled glass gives an irregular surface of the wire, including chip formation, which can improve the lubricant carrying ability of the wire rod surface, but also increase the risk for reduction of the fatigue strength of the wire.

The differences of die wear using wire rods descaled by two treatments; pickling and reversed bending has been studied. The study gave a background of wear mechanism and described a method to estimate die wear in wire drawing. The conclusions of the experiments indicate that the method for wire rod preparation seems to be of minor importance for the wear of die. The wear rate of a die used in the sixth draft was one order of magnitude lower than the wear rate of the die in the first draft. Abrasive wear is present presumably from the WC grains, torn out in the adhesive wear, on both dies used on pickled wire rod and reverse bent and steel wool cleaned wire rod.

In order to evaluate new methods to descale wire rod, the effect of thermal shock has been studied. An estimation of the stresses, developed in the oxide during cooling after hot rolling and a FEM-simulation during cooling from ambient temperature down to 77 K, has been made. Experiments using liquid nitrogen, flame and steam to descale wire rod have been performed with mild steel and silicon and chromium steel wire rod. The experiments have shown that thermal shock cannot descale the wire rod. Only a descaling effect from the flame has been found.

Place, publisher, year, edition, pages
Örebro: Örebro universitetsbibliotek , 2006. , p. 26
Series
Örebro Studies in Technology, ISSN 1650-8580 ; 22
Keywords [en]
Mechanical descaling, shot blasting, pickling, steel wire rod, wear, drawing
Research subject
Mechanical Engineering
Identifiers
URN: urn:nbn:se:oru:diva-376ISBN: 91-7668-471-7 (print)OAI: oai:DiVA.org:oru-376DiVA, id: diva2:136734
Public defence
2006-04-07, Hörsal T, Teknikhuset, Örebro universitet, Örebro, 10:00 (English)
Opponent
Supervisors
Available from: 2006-03-17 Created: 2006-03-13 Last updated: 2017-10-18Bibliographically approved
List of papers
1. Determination of scale amount on wire of carbon steels and low alloyed steels
Open this publication in new window or tab >>Determination of scale amount on wire of carbon steels and low alloyed steels
2003 (English)In: Wire Journal International, ISSN 0277-4275, Vol. 36, no 9, p. 73-77Article in journal (Refereed) Published
Abstract [en]

Scale amount on wire of carbon steels and low alloyed steels was discussed. Metal microscopy and scanning electron microscopy were used. It was found that this method can determine the scale determinations after the material has been stretched.

Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-3063 (URN)
Available from: 2006-03-17 Created: 2006-03-17 Last updated: 2017-10-18Bibliographically approved
2. Replacement of pickling with shot blasting for wire rod preparation
Open this publication in new window or tab >>Replacement of pickling with shot blasting for wire rod preparation
2004 (English)In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 33, no 5, p. 269-278Article in journal (Refereed) Published
Abstract [en]

An oxide scale layer covers steel wire rod produced by hot rolling. This oxide is often removed by pickling before wire drawing; otherwise, hard oxides will be impressed into the wire surface and give an inferior surface quality. Stricter pollution regulations increase the incentive to replace pickling with mechanical descaling. This paper gives results from tests on carbon steels by using shot blasting to descale wire rod. The tests include: (i) shot blasting experiments in an industrial full-scale in-line shot blasting machine, (ii) laboratory drawing experiments on shot blasted wire rod, (iii) industrial trials on shot blasted wire rod at the drawing plants. There are differences in the appearance of surfaces between shot blasted and pickled wires, but no differences in the drawing process were observed in the laboratory experiment. In the industrial trials the wear of dies were more severe when drawing shot blasted wire of one of the steel grades. In the downstream processes, problems were recorded with the cleanness of the surface of another grade and adhesion of copper coating on a third grade.

Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-3064 (URN)10.1111/j.1600-0692.2004.00692.x (DOI)
Available from: 2006-03-17 Created: 2006-03-17 Last updated: 2017-12-14Bibliographically approved
3. Mechanical descaling of wire rod using reverse bending and brushing
Open this publication in new window or tab >>Mechanical descaling of wire rod using reverse bending and brushing
2006 (English)In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 172, no 3, p. 332-340Article in journal (Refereed) Published
Abstract [en]

Wire rods are covered with an oxide layer, which must be removed before wire drawing. This paper presents an investigation of mechanical descaling by reverse bending and brushing as replacement for pickling. Steel grades studied were low carbon steel and silicon chromium steel. Brushing was done with steel brushes and nylon brushes with SiC. The amount of scale remaining after reverse bending of the low carbon steel depended on the roller diameter. After brushing traces of scale remained in valleys on the surface. Surface damage was observed after brushing with steel brushes but not after SiC-nylon brushing. Silicon chromium alloyed steel was not possible to clean by bending and brushing with the roller diameters studied. The electrical energy required for the mechanical descaling of low C steel may be estimated to be 7kWh/tonne with SiC-nylon brushes and 14kWh/tonne with steel brushes. [All rights reserved Elsevier]

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2006
Keywords
bending, carbon steel, drawing (mechanical), pickling (materials processing), rods (structures), rollers (machinery), wires
National Category
Engineering and Technology
Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-4438 (URN)10.1016/j.jmatprotec.2005.10.014 (DOI)
Available from: 2007-07-12 Created: 2007-07-12 Last updated: 2017-12-14Bibliographically approved
4. Shot blasting of billets and wire rod
Open this publication in new window or tab >>Shot blasting of billets and wire rod
2005 (English)In: Metallurgy and new materials researches, ISSN 1221-5503, Vol. 13, no 4, p. 1-21Article in journal (Refereed) Published
Abstract [en]

A model for work and power in shot blasting is derived. A study is made to use recycled glass as a shot blasting media. The theoretical model must be adjusted for strain hardening material. The experiments indicate that the average shear yield stress is more than twice the initial value for austenitic stainless steels. Soft materials get rough surfaces in shot blasting, which can be advantageous for the ability to carry the wire drawing lubricant. Recycled glass is a possible shot material. Due to the lower density, the shot velocity must be higher than for steel shots. This effect becomes larger by rotation of the glass shots during operation. Recycled glass gives irregular surface, including chip formation, which can improve the lubricant carrying ability of the wire rod surface, but also increase the risk for reduction of the fatigue strength of the wire.

Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-3066 (URN)
Note
Tidskriftens parallelltitel: Cercetari Metalurgice si de noi MaterialeAvailable from: 2006-03-17 Created: 2006-03-17 Last updated: 2017-10-18Bibliographically approved
5. Wear of die after drawing of pickled or reverse bent wire rod
Open this publication in new window or tab >>Wear of die after drawing of pickled or reverse bent wire rod
2007 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 262, no 7-8, p. 858-867Article in journal (Refereed) Published
Abstract [en]

The object of this paper was to evaluate the difference of die wear by using wire rods descaled by two different treatments; pickling or reversed bending. The paper gives a background of wear mechanism and describe a method to estimate die wear in wire drawing. The conclusions of the experiments were that the wire rod preparation seems to be of minor importance for the wear of die. A die in the sixth draft had a magnitude lower wear, compared to the die in the first draft. Abrasive wear is present from the WC grains, torn out in the adhesive wear, on both dies used on pickled wire rod and reverse bent and steel wool cleaned wire rod. © 2006 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2007
Keywords
Descaling, Drawing dies, Pickling, Wire drawing, Wire rods, Adhesive wear
National Category
Engineering and Technology
Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-4354 (URN)10.1016/j.wear.2006.08.016 (DOI)
Available from: 2007-07-12 Created: 2007-07-12 Last updated: 2017-12-14Bibliographically approved
6. Descaling of wire rod by using the effect of thermal shock: liquid nitrogen, steam or flame
Open this publication in new window or tab >>Descaling of wire rod by using the effect of thermal shock: liquid nitrogen, steam or flame
(English)Manuscript (preprint) (Other academic)
Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-3068 (URN)
Available from: 2006-03-17 Created: 2006-03-17 Last updated: 2017-10-18Bibliographically approved

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