Tribology in iron and steelworks

ln conclusion, this type of meeting is one which could well be repeated to advantage in other branches of tribology. Dr Summers-Smith did, in fact, suggest that ‘other types of wear’ could provide a suitable topic. Perhaps the fact that there will be no official record of the proceedings was a help in stimulating discussion and in persuading the people concerned with the more practical aspects to participate. The relatively small attendance-about GO-also served to encourage informality. The Materials Science Club are to be congratulated. J. K. Lancaster

The abrasive wear of rubber Schallamach, A. (NRPRA, Welwyn) The abrasive wear of brittle solids Brookes, C.A. (University of Exeter)

1969

TRIBOLOGY IN IRON AND STEELWORKS The Iron and Steel Institute and the Institution Engineers

structure College, London)

Erosion/cavitation processes and fracture Field, J. E. (University of Cambridge) The wear of rubber lyres Schallamach, A. (MPRA, Welwyn) Aspects of the wear of carbon on copper Bale, E. S. (Morganite Carbon, Battersea) Sand erosion of metals and plastics Tilly, G. (NGTE, Pyestock) Wear of cutting edges in agricultural soils Richardson, R. C. D. (NIAE, Silsoe) The role of cast alloys in resisting abrasion by cement clinker Dodd, J. (Bradley & Foster, Darlaston) Hard products developed during sliding wear Eyre, T. S. (Brunei University) Abrasion in the dentifrice industry Wright, K. H. R. (NEL, East Kilbride) The correlation between wear trials and abrasion tests of sole leather Mitton, R. G. (BLMRA, Egham)

Conference papers The abrasive wear of metals Richardson, R. C. D. (NIAE, Silsoe) The abrasive wear of polymers Lancaster, J. K. (RAE, Farnborough)

London, 22-25 September

Abrasion and surface Wilman, H. (Imperial

of Mechanical

Latroductory session Better tribe-practice could save f 20,000,OOO annually in the UK iron and steel industry. Mr H. Peter Jost put forward the figure as an extremely conservative one in his opening address. A four million ingot ton intergrated steel works could save f 3,000,OOO each year, which on today’s small margin could easily change a profit into a loss. He urged delegates at the conference not to buy unnecessary operating cost. From that point, Dr H. Finniston, Technical Director of British Steel Corporation, took up the tale. Tribology was important because of the fashionably synergistic effect of physicists, chemists, metallurgists and engineers. But it would be wrong to think merely of bearings and lubrication. Wear rates of abrasive coke in shutes; slurries in transport; and the movement of steel in moulds and through mills all constituted worthwhile studies which were part of tribology. The conference as a whole showed a pleasingly pragmatic approach, said Dr Finniston, which was realistic because wear and friction are inexact subjects on which the designer hadlittle guide. Design against wear could not take the failsafe form that was so common in electronics and other industries. Metallurgists have a great deal to contribute which was often not fully understood by engineers. Metallurgy should be systematic and greater use should be made of techniques such as electron-microscopy and X-ray diffraction. These were not sufficiently known in the works. Finally Dr Finniston emphasised that tribological problems will become more and more important as productivity increases and quality rises. Session A-Wear in sinter plants and tranSpartatioa One of the common causes of wear in sinter plant is abrasive wear in chutes, bunkers, etc. Haucke indicated various ways of reducing this type of wear. The most successful method was using a protective liner of Zac 1661 (fusion-cast corundum and zirconium oxide). By standardizing linear plates sizes, shapes and methods of fixing it is possible to

make this relatively expensive material economically viable. Hocke’s paper described tests on a range linings under abrasive sliding wear conditions. He also considered the relationship between simulated and field test. An interesting paper was given by Babb describing the wear of rails in iron and steelworks. The principle causes of wear in rails are abrasion, oxidation and plastic flow. A contorgraph was used to assess wear profiles of rails. With axle loads up to 25 tons the main cause of wear is oxidation and there is little to be gained by using a harder steel. On tracks where the axle loads are over 35 tons rail steel to BSll fails rapidly by plastic flow and the use of harder steel is very worthwhile. Sessicm 1 Cold working

processes

other than rolhg

The first three papers of this session concentrated on wire drawing. Johnson and Rowe working at Birmingham University had graded lubricants in a wire drawing die by drawing with a severe pass of 35-40” at drawing speeds of up to 2.3 metres per minute. They based their results on only one measurement, the drawing force, and then calculating .u from a redundant work factor. This procedure drew some comment but it was generally agreed practically valid as a method of rating lubricants and if the pass was severe. Dieangles of 5-10” were used. The best lubricant is generally the one with the lowest coefficient of friction, so long as it satisfies other requirements such as corrosion resistance or the need for a bright surface. Pressurized lubrication of the die offers one solution to the problem of wear on the inlet die. Polyethylene glycol has been chosen as the lubricant because it can withstand the pressures of around 690 x lo6 N/m2 and can work at viscosities of around 1,OOOS. The inlet sealing die is replaced by a tube to mitigate wear and the clearances must be held as close as the ovality of the wire allows. A multi-hole die of this design will be going on to test soon. The author, Mr Middlemiss, is in the Mechanical Working Division of BISRA. Phosphate coatings frequently allow coating and drawing sequences to be simplified and for several passes to be made without re-coating. Reductions of 40”& are easily achieved and the coatings can be applied in as little as 15 seconds. One paper from the Pyrene company, by James and Haynes gave several examples of the use of such coatings to simplify wire drawings. Subsequent papers provoked a useful discussion on surface roughness. Dr L. H. Butler, University Tribology

November

1969

245

College, Cardiff put in a plea for much greater use of instruments such as the Talysurf and the interferometer in measuring surface roughness and showed some dramatic examples of the simple use of interferometry. His namesake R. D. Butler from Pressed Steel Fisher spoke of the value of surface roughness in cold pressing. Roughness must be controlled and a coarser surface can often eliminate scoring. The tool also has a surface roughness, which must be taken into account, and which must be different from the sheet roughness. Almost any lubricant would do for most stampings, so long as it would contaminate the surface. Ease of application, lack of decomposition in welding and smell are much more important. So also were corrosion portection and ease of removal. The UK and American methods of measurement over emphasise the differences in roughness of sheets supplied. Dr Pawelski said that Polish work had shown that/vibration could help deep drawing. Sessim B Tribology in the sect&m and operation of roll neck -ings This session was marred by inability to hear the speakers either direct or through the continuous translation system.

Too many of the speakers muttered their papers at high speed. Therefore anybody who wants to find out what they said would do well to read the conference proceedings or to buy a copy of the reprints from the Iron and Steel Institute. The notable exception was Professor F. T. Barwell who gave a clear talk on some particular aspects of hydrostatic lubrication in steelworks. In particular he dealt with a screw down gear, how to use the available pressures of around 200 x 105 N/m2 to carry the screw down shaft which might be subjected to momentary loads of lo7 Newtons and should theoretically require a pocket pressure of 70 X 10s N/m2 as part of a hydrostatic bearing. After this the session turned itself into an argument, and a very fruitful one at that, on the merits of oil mist lubrication versus roller bearings. The proponents of roller bearings admitted that the theory favours the oil mist theory but emphasised that with roller bearings there is no change of gap in the roll neck. oil mist bearings also introduced the questions of oil fog in the works, which has to be extracted and of roll neck heat which may require a close circulation system to extract it. Waste oil has to be disposed of. In answer the proponents of oil mist cited that fact that they by adding polymers to the oil spray they have largely suppressed oil fog and that they did regularly sample the atmosphere in works where oil mist lubrication was used. On the question of accuracy, it was agreed that the gauge during acceleration and decelaration periods were not the main issue as handling damage and other factors caused the ends of the rolls to be scrapped in any case. Session C-Tribolqg in warm and hot metal working A. Thomas from the Drop Forging Research Association pointed out that the development of new materials for forging dies is slow. He outlined the difficulties of testing die materials in the forge and indicated the results obtained from a simulated wear test. Professor Halling read Thomason and Fogg’s paper which described a plane strain compression test used to assess warm working lubricants. This rapid sorting test showed that a graphite-cadmium oxide mixture could be the most promising for this type of work. A comparison between some filled salt lubricants and glass for extrusion of stainless steel at 1200°C was made in N. J. Parratt’s paper. He said there appeared to be a balance between minimum lubricant viscosity and quantity required for effective lubrication. The best salt lubricant tested gave a smoother finish than the glass lubricant. Surface oxidation after hot extrusion was not prevented by the salt and a cleaning pickle was required. The final paper in this session which discussed the effects of hardness on abrasive wear by Hirano and Ura was not presented. Sessim D-‘hibology

educatia~

and braining

for steelwarks

Probably the most important point which R. Duncan made was that all levels of the workforce should be cbnsidered when 246

Tribology

November

1969

training staff and that training should continue throughout one’s working life. Henke described the training of lubrication specialists in the German Democratic Republic. He said that since 1950 the principles of lubrication technology have been taught to engineers at various levels. Since 1960 training programmes at higher levels have gradually been introduced. In the discussion there was a great call to train unskilled workers, but then there was general agreement that foreman and management should be trained before their staff. Peter Jost pointed out that at the unskilled level lubrication was the main part of the training required, whereas at the higher levels (up to post-graduate) the scope of training should include the whole field of tribology. Dodd gave a general background to programmed learning. An industrial seminar on tribology held at the Swansea Tribology Centre was described by Barwell. He also mentioned the place of tribology in undergraduate education of engineers. Henderson described a course run by ShellMex and BP for their customers. It allowed a large degree of feedback from the participants to the intstructors so that its value could be ascertained quite easily.

Session

2-Hot

roll

wear

Johnson and Sturgeon discussed the mechanism of roll wear in hot mills with reference to the finishing trains of highspeed bar and rod mills. The main wear mechanisms occuring in these mills is abrasion and methods of reducing abrasive wear were reviewed. For obvious economic reasons the metallurgist must try to extend the service life of the roll working surface as much as possible. A paper from Czechoslovakia considered this problem and gave particular attention to electroslag surfacing. The last paper in this session also discussed surfacing in Czechslovak metallurgical plants. Crane wheels are one source of trouble and it was estimated that on average every crane wheel should be replaced once per year. Instead of scraping they can generally be renovated by surfacing. The most suitable method at present is submerged-arc surfacing. Rams in extrusion presses are also subject to wear and as they can weigh up to 30tons they would be too expensive to scrap. As much as 2000kg of overlay metal might have to be deposited on large rams to withstand operating conditions. High-alloy metals with a chromium base have been successful in such conditions.

Session

IZ-Tribo-design

and

maintenance

This session dealt mainly with case histories of particular pieces of iron and steelworks plant. At the Dorman and Long complex on Teeside there are three mills served by 440 ingot bogies. c150,OOO was spent on lubrication, repair, and maintenance of these bogies during 196’7. K.Anderton said that among the systems needing thorough investigation were: the development of a more rigorous greasing and inspection system; the determination of the major causes of wheel bearing failure the determination of the effect on the bogie structure and bearing life of shock loads (during the stripping operation impact loads of several thousand tons can be encountered); the determination of the effectiveness of the present bearing lubricant, especially with reference to the high-temperature working conditions; the comparison between the life of new and welded tyres; the comparison between the wearing rates of the tyre flanges (a) lubricated with a graphite stick, and (b) dry (during 1967 the weight of metal removed from the bogie tyres by wear was about 17 tons); the effectiveness of grease and solid lubricants on the axle bearing slide (this area is subject to very high temperatures and when running dry the wear rate is in the region of l/,in/year on an original dimension of 14in); and finally the effect on lubricating the extended horizontal coupling pin, A comprehensive survey of wire rope lubrication was given by Hoyland and Brown. An experimental study of transmission of grease in pipelines followed by a progress report on an NLGI project to predict pressure drops in grease distribution equipment concluded the session.

Sessim F-Tribology in cold rolling Friction and lubrication in cold rolling will affect the quality of strip, the speed or rolling and the wear rate of rolls. The fallback is eventually on the lubricant. W. L. Robert’s paper outlined lubricant’s effect on rolled strip. Roberts said that much is still to be understood about the behaviour of the dynamic components of the rolling system. Cubitt and Eyres from Mobil gave details of the processes involved in the development of a synthetic cold-rolling lubricant. They considered the Falex machine to be a useful rapid screening tool for potential new formulations, and also described a small laboratory mill used for lubricant evaluation. Session COrganizatid and management aspects of ~b0b-Y This final session dealt with one of the most important aspects of tribology, namely management: Newman and Todd attempted to analyze the position of the engineering specialist in industry and apply their ideas to the technologist concerned with tribology. Rappini reviewed experience with ‘information cards’ at major iron and steelworks in Italy. The cards act as an information system to aid preventative maintenance. Brauer’s paper also dealt with preventative maintenance but from an economic viewpoint. Hewit pointed out that over the last two decades the lubrication engineer’s position has gradually become more important. His role now not only includes selection and design of plant but also training and education of staff. Gulker described the possibilities for computer use in the iron and steel industry for tribological problems. Computers can be used for data processing jobs such as listing lubricants and lubricant consumption as well as aiding the design of such equipment as hydrodynamic journal bearings and gear trains.

16 17

18 19

20

21

Hydrostatic lubrication in steelworks, Barwell, F. T. (Swansea Tribology Centre) Comparative rolling contact fatigue tests on En 31 ball bearing steels, Scott, D. (National Engineering Laboratory) The wear of drop forging dies, Thomas, A. (Drop Forging Research Association) The determination of the coefficient of friction at warm working temperatures, Thomason, P. F., Fogg, B. (University of Salford) Coefficient of friction and temperature distribution during hot forming of steel with different lubricants, Pawelski, 0. (Max-Planck Institut fur Eisenforschung) Graue, G., Lohr, D. (August Thyssen AG) The problem of friction in rolling and forging processes, Gierzynska, M. (Politechnik Czestochowska, Poland)

22

Filled salt lubrication of extrusion, (Ministry of Technology)

Parratt,

23

Wear caused by abrasive particles, (Kyushu University, Japan)

Hirano, F., Ura, A.

24

Technical training requirements in the iron and steel industry, with specific reference to tribology, Duncan, R. (Iron and Steel Industry Training Board)

25

Systematic training of lubrication specialists in the German Democratic Republic, Henke, H. (Riesa Engineering College)

26

Programmed instruction (University of Sheffield)

27

Education in tribology for engineers, (Swansea Tribology Centre)

Conference papers 1 Wear problems in sinter plants and their solution, Haucke, M. (Hoesch AG) 2 Wear resistant lining materials for steelworks chutes, Hocke, H. (BISRA/IGL) 3 An exercise in the redesign of tray conveyor pins and bushes on a sinter plant, Court, H. V. (BSC, South Wales Group) 4 Wear resistant materials for dry bearings operating under dirty conditions, Allison, J. W. (BISF?A/IGL)

28

Training of plant and works engineers in lubrication principles and practise, Henderson, M.A. (Shell-Mex B.P. Ltd)

5 6

7 8

The wear of rails in iron and steel works, Babb, A. S. (BSC, Midland Group) Evaluation of coefficient of friction in wire and bar drawing, Johnson, R. W., Rowe, G. W. (University of Birmingham) Hydrodynamic lubrication for drawing steel wire, Middlemiss, A. (BISRA/IGL)

Chemical conversion coatings facilitate metal working lubrication, James, D., Haynes, J. E. (Pyrene Ltd) 9 Surface roughness and lubrication in press working, Butler, R. D. (Pressed Steel Fisher Ltd) 10 Friction, lubrication and surface effects during the cold working of metals, Butler, L. H. (University College of South Wales) 11 Process lubrication in steel tube manufacture, Aitken, R., Hamilton,A., Riley, R. V. (BSC, Northern and Tubes Group) 12 Back up roll bearings for cold reducing mills, Cichelli, A. E. (Bethlehem Steel Corporation) 13 Oil film roll neck bearings for cold reducing mills, Rickley, S. S., Bjork, J.A. (Morgoil Bearings) 14 New mist lubrication concepts for tapered roller bearings used on high speed rolling mill back up rolls, McCoy, W. E., West, C. H. (The Timken Roller Bearing Co) Wilks, P. E. (British Timken) 15 Roll neck bearings under severe operating conditions, Strafe, G., Munnich, H. (SKF Kugellagerfabriken)

and tribology,

N. J.

Dodd, B. Barwell,

F. T.

and

29

Roll wear in rod finishing stands of high speed hot section mills, Johnson, T. W., Sturgeon, G. M. (BISRA/IGL)

30

On problems of wear of groove rolls in continuous rolling mills and of grooves of pilger rolls, Blaskovic, P. (Welding Research Institute, Bra&lava) Dorda, J. (Trinec Ironworks) Nainar, J. (Central Research Institute, Skoda) Matous, 0. (Tubes and Iron Rolling Mill, Chomutov)

31

How to achieve economic surfacing of wearing surfaces in metallurgical plants, Hano, 0. (Welding Research Institute, Bratislava) Nainar, J. (Central Research Institute, Skoda)

32

Bloom mill universal Midland Group)

33

Some tribological factors in plant design and maintenance, Rappini, G., Vaccaro, I. (Italsider)

34

Wear and maintenance problems on a fleet of 440 ingot bogies, Anderton, K. (BSC, Northern and Tubes Group)

35

Improvement in design of a fabric M. C. (BSC, Midland Group)

36

Case histories-Improvement in operating efficiency by the logical application of lubricants, Hobson, W. C. (Ed) (BSC, Midland Group)

37

Reports Margam

38

Reducing maintenance of wire ropes in service in iron and steel works by lubrication, Hoyland, R. H., Brown, W. (Centralube Ltd)

39

A study of the compressibility of grease and transmission of grease in pipelines, Jackson, A. G., Morris, N. R. W. (Farvalube Ltd) Gesdorf, E. J. (Farval Division, Eaton Yale and Towne inc.)

40

Effects of friction on the cold rolling W. (BSC, South Wales Group)

maintenance,

Bowns, E. (BSC,

bearing

chock, Brown,

on lubrication and wear problems at Abbey and works, Newman, L. V. (BSC, South Wales Group)

Tribology

process,

November

Gregory,

1969

247

41

42 43

44

Surface defects of a frictional origin in wide strip mill products, Thickens, J. B., Salmon, C.E. (BSC, South Wales Group) Influence of rolling lubricant on sheet and strip quality, Roberts, W. L. (United States Steel Corporation) Tribology applied to the production of cold rolled steel strip in high speed tandem mill operations, Ohm, A (Quakef Chemicals, Holland) Ichinoi, J. (Science University of Tokyo and Nippon Quaker Ltd) Tomizawa, T. (Science University of Tokyo) Development of a chemical rolloing oil, Cubitt, A. H., Eyres, A. R. (Mobil Oil Co. Ltd)

45

The influence of cold mill processing conditions on the formation of snakey edge on cold reduced sheet, Strefford, R., McCallum, N. (BSC, Scottish and Northwest Group)

46 47

Rolls for cold rolling, Lucas, G. (Firth-Brown Ltd) Preventing mechanical damage to the surface of stainless steel strip during manufacture, Spalton, T. H. (FirthVickers Ltd)

Limits

Tribology

49

Information cards for maintenance of metallurgical investigations in iron and steel-how the system works to reduce costs in friction and wear, Rappini, G. (Italsider )

50

Evaluation of tribological performances ratios, Warlich, R. (VDEh)

51

Economic and administrative problems of lubrication in steelmaking and rolliig plant planned maintenance the German Democratic Republic, Brauer, V. (VEB Tube Combine, Steelmaldng and Rolling Plant, Riesa)

with the aid of

in

52

The practical lubrication Hewit, W. (BSC, Northern

engineer-his place in industry, and Tubes Group)

53

The use of computers for lubrication problems in the German iron and steel industry, Gulker, E. (Hoesch AG)

at an international discussion conlubrication laboratory, Imperial No report of proceedings of the of the authors have agreed to have

lubrication

G. V. Vinogradov (Petrochemical Synthesis, Academy of Sciences, USSR) The theory of boundary lubrication usually proceeds from models of the existence at solid boundaries of two-dimensional crystalline or quasi-crystalline layers of biphylic long-chain aliphatic compounds. These ideas are feasible if the lubricating medium contains such compounds, say as additives, and if it is employed, besides, under mild friction regimes, when the metal wear is low, that is, when friction is accompanied by breakdown and regeneration predominantly of the boundary layer, and the metals are not significantly bared. However, ordinarily the petroleum oils in general use do not contain long-chain aliphatic compounds as such. Alkaline earth alkyl sulphonates and alkyl phenolates are used as oil additives and they are adsorbed by metals. But it is not known to what extent their adsorbtion layers obey the classical scheme of structure at boundary lubricant layers. Besides, and this is especially important, it is necessary to take into account not only adsorption processes. It is significant that the systems constituting friction pairs consist of many phases and components. In actual machine assemblies friction.involves various phases in which irreversible changes take place. This is essential for technical-grade metals, which usually have, in addition, a phase composition gradient extending from the surface into the bulk of the metal. Of major importance also are the layers of oxides and other inorganic compounds on metal surfaces, which form the substrates of the boundary layers. Changes in the phases in friction pairs can be detected distinctly unless the friction regimes are especially mild and involve imperceptible wear of the metals. During metal friction in hydrocarbon media wear of the oxide layers is accompanied by a complex chain of processes. Baring of the juvenile metal surface, as in the case steel, causes an exothermic oxidation of these metals. This reaction initiates oxidation of the hydrocarbons contained in the 246

An examination of management structure in industry with particular reference to the role of the engineering specialist, Newman, A. D. (Centre for Organization Analysis) Todd, J. P. (BSC, Northern and Tubes Group)

of lubrication

Ten informal papers were presented ference organised by Dr, Cameron’s College, London on 21-25 July 1969. conference will be published. Some their papers published in Tribology.

Boundary

46

November

1969

petroleum oils, resulting in unstable products of their oxidation- hydroperoxides and peroxides. These are active oxidants with respect to metals. Thus, oxidation of metals and of hydrocarbons in friction pairs are conjugate processes. Oxidation of hydrocarbons results in drastic transformation products, including resinous substances. Being very viscous and adsorbing on the oxide layer, they may affect the friction conditions substantially, favouring an elastohydrodynamic regime. Development of the processes under consideration depends substantially on the composition of the lubricating medium. This is a fact of general significance, extending beyond the scope of lubricating oils. The same was recently shown by Akjenov during steel friction in fuel media. Indeed, the differences between the anti-wear and anti-friction properties of fuels are no smaller than those among petroleum lubricating oils. The ready oxidizability of hydrocarbons, which favours rapid regeneration of oxide layers and the formation of resinous highly viscous substances, may compensate for their low viscosity to such an extent that sometimes even low-molecular organic compounds may exhibit good lubricity. It is clear that this has nothing in common with the classical theory of boundary lubrication. The positive role of oxidation processes in steel friction in hydrocarbon media is enhanced on passing over to more drastic regimes, when regeneration of the oxide layers on the metal surfaces is especially important, since it prevents seizure. On the other hand, at milder friction regimes oxidation processes cause corrosive wear. Thus within definite limits the lubricating medium may fulfil the regulating function of a deliverer of molecular oxygen and active oxygencontaining compounds or of a barrier retarding their delivery to the metal surface. This is the thesis of optimum oxidation processes during sliding friction. This optimum is usually