U N I V E R S I T Y O F M 0 R A T U 11 A Department of Material Engineer ins ;';>• Faculty of Engineering The production of alloyed white cast iron for the use in the crushing and grinding operations in Sri Lanka By Jayasuriya Hudiyanselage Ranasinghe Banda ! • . . OF Ceyloii^Steel Corporation and part-time student I;' department of Materials Engineering •'-'University of Moratuwa j j' A dickertation submitted for the degree of Haster\,of Science in tiie University of Moratuwa December 1981 1 . ' C 0 N T E M T S PREFACE ACKNOWLEDGEMENT. SYNOPSIS: 1. Introduction - 1 1.1 Steel and Cast Iron used in the Grinding Operation 1.2 Cost Analysis of grinding media used in Sri Lanka 1.3 Types of steel and cast iron l e4 Object of the study 1.5 Application in Sri Lanka 2. Litreature Survey ?3 - 43 2.1 White iron formation 2.2 Metallurgy of white cast iron . i,.2.3 Alloyed white cast iron 2.3.1 Low chromium white cast iron 2.3.2 Nickel chromium white cast iron 2.3.3 Chromium Molybdenum-white cast iron 2.3.4 High chromium white cast iron 3. Metallurgical Principles of the Effect of Alloying '•r- - 7', Elements in Cast Iron 3.1 Effect of alloying elements on reaction. 3.2 Effect of alloying elements on microconstituent and properties 3.3 Effect of specific alloying elements on cast iron 3.3.1 Chromium 3.3.2 Silicon 3.3.3 Copper 3.3.4 Phosphorus 3.3.5 Molybdenum 3 . V , Manganese 3.3.7 Vanadium 3.3.8 Hickel 3.3.9 Sulphur 3.3.10 Tin Microscopic Constituents of Cast Iron and Steel 4.1 Ferrite 4.2 Graphite 4.3 Pearlite 4.4 Austenite 4.5 Martensite 4.6 Ledeburite 4.7 Steadite 4.3 Troosite 4.9 Sorbite Pattern and Mould Making 5.1 Solidification and risering of liner plate 5.2 Design of pattern plate for grinding media 5.3 Moulding techniques 5.4 Moulding materials 5.5 Properties of moulding materials 5.5.1 Permeability 5.5.2 Moisture content 5.5.3 Refractoriness 5.5.4 Green strength 5.5.5 Dry strength 5.5.0 Flowability 5.5.7 Zirconium sand for.white cast iron casting (iii) 6 Manufacture of, white cast iron 6.1 Fettling 6.2 Heat treatmei 112 - 133 7. Analysis of casting defects 7.1 Blow holes and pin holes 7.2 Shrinkage cavitie3 7.3 Fusion 7.4 Erosion scab 7.5 Swells 7.6 Broken or cracked castings 7.7 Hot tearing 7.8 Quench cracking 7.9 Metal mould reaction 7.10 Metal penetration 7.11 Misruns 134 - 154 8. Properties of alloyed white cast iron 8.1 Wear resistance 8.2 Factors affecting wear resistance 802.1 Hardness 8.2.2 Microstructure 8.2.3 Surface structure 8.2.4 Hardenability 8.2.5 Average volumetric hardness 9. Microstructure 155 - 171 172 - 181 9.1 Structure of grey cast iron 9.2 Solidification and microstructure of white cast iron 9.3 Carbide morphology 9.4 Chemical composition of carbides (iv) 9.5 Relation betv;een chemical composition and carbide content 9.6 Matrix 10 Experimental work carried out 182 - 1 9 8 1 0 . 1 Selection of chemical composition 1 0 . 2 Manufacture 1 0 . 3 Mechanical testing 1 0 . 4 Hear testing 1 0 . 5 Hardness testing 10.6 Fracture stress 8tensile testing) 1 0 . 7 Microstructural analysis 1 0 . 8 Impact testing 1 1 Discussion •jgg 210 1 1 . 1 Moulding 1 1 . 2 Melting 1 1 . 2 . 1 Nickel chromium white cast iron 1 1 . 2 . 2 High chromium white cast iorn 1 1 . 2 . 3 Martensitic Cr-Mo white cast iron 1 1 . 2 . 4 Low Cr whitcv cast iron 1 1 . 3 Cost analysis 12 Conclusions oin oon P.ef erences Appendix I (v) ? H 3 F A C This dieeertaticr. x* an account of the v/o.:k carried out in the department of "etcrialc Thiginesring, t'::ivcrsi fcy of ?.loratuv;a a::d the Ceylon Cfteel Corporation from .January 19'-0 to Deceab.c-r 1?81. A'section of the dissertation, has been cent for publication ir. an international journal. A cvrr.ary of this vorked described in this thesis v/j.ll also bo discusrod -at th-, an-ual session of tho S.L.A.S.S. to bo held in nid December. The results described in this dissertation ere to the best of r.vy knowledge, original except vht-re reference ic, made to the v;ork of others, v.o part of this dissertation has boon subtr.itted for a degree at any other 'University. Department of Materials "n^ir.eoring, he 3anc!a •University of "cratuY.-a, (vi) A C K N O W L E D G E M E N T S I would like to express my most sincere appreciation and deep gratitude to my supervisor Professor Ayal De .S. Jayatilake for his encouragement, supervision, helpful criticism and perso­ nal understanding throughout the course of this project. My sincere thanks are also extended to Dr. H.I. Marshall of the University of Leeds and Mr. Mohan Edirisinghe for their valuable advice. Appreciation is expressed to Messers. Garath Chandrapala, Sarath Wijeainghe, Ananda Suraweera and the rest of the members of the department of Materials Engineering for their willing assistance. I record my gratitude to Mrs. Champa Abeyaratne for typing the manuscript, and to the staff of the Foundry, metallography laboratory, work-shop, chemical and mechanical testing laboratory of tho Ceylon Steel Corporation for the assistance given to me at various stages. I wish to thank also the Chairman, Ceylon Steel Corporation for giving me this opportunity to work on a part time basis at the University of Koratuwa. (vii) S Y N O P S I S This thesis describes the work that have been carried out to produce different types of cast iron grinding media and liner plates of good wear resistant quality for the local industry. The types produced were •low chromium, nickel chromium, martensitic and high chromium white cast irons. The castings were carried out at the Ceylon Steel Corporation while the micro structural examination and mechanical testings were conduct3d at the University of Moratuwa. At present low alloyed cast steel grinding balls and Hadfield steel liner plates are produced at the Ceylon Steel Corporation for local use and they are found to contain defects ranging from shrinkage cavities, sand fusions, blow holes, quench cracks to misruns. It i3 possible to eliminate most of these defects with certain types of alloyed white cast iron. The grinding balls and liner plates so produced showed greater resistance to wear and the casting yield was higher when compared with the castings of balls and liners. Although the price of alloyed white cast iron is marginally higher than the. cast steel balls and Hadfield liners, the longer life of the former more than compensates the replacement of cast steel balls, Hadfield liners with the white cast iron balls and liners.