Triennial Report 2003 - CHARMEC

Materials and maintenance – Material och underhåll (MU) – Werkstoff und Unterhalt – Matériaux et entretienMU2. NEW MATERIALS IN WHEELS AND RAILSNya material i hjul och rälerNeue Werkstoffe in Rädern und SchienenNouveaux matériaux pour roues et railsProject leaderand supervisorProfessor Birger Karlsson,Engineering Metals(now Materials Scienceand Engineering)Doctoral candidate Mr Johan Ahlström(from 1995-11-01;Lic Eng December 1998;PhD March 2001)Period 1995-07-01 – 2001-06-30Chalmers budget Stage 1: ksek 1400(excluding university Stage 2: ksek 1800basic resources) Stage 3: ksek 325Industrial interests Stage 1: ksek 200in-kind budget Stage 2: ksek 300(Adtranz Wheelset/ Stage 3: ksek 100Lucchini Sweden)materials have now been extensively tested at Chalmersand Lucchini for fatigue behaviour (under strain control)and fracture toughness (Charpy V down to –40 °C).Candidates for improved material quality in the wheelshave been found.On 2 March 2001, Johan Ahlström successfully defendedhis doctoral dissertation (see below) in public.Professor Ian Hutchings of the Department of MaterialsScience and Metallurgy at the University of Cambridge,uk, served as the faculty-appointed external examiner.The mu2 project was concluded as planned by 30 June2001. Since April 2001, Johan Ahlström has been employedas Assistant Professor at Chalmers EngineeringMetals (now Chalmers Materials Science and Engineering).See further the charmec Triennial Report fromStage 2.Johan Ahlström: Thermal and mechanical behaviour of railwaywheel steel, Doctoral Dissertation, Chalmers EngineeringMetals, Gothenburg February 2001, 142 pp (summary and sixappended papers)Johan Ahlström and Birger Karlsson: Modified railway wheelsteels – production and evaluation of mechanical properties withemphasis on low cycle fatigue behaviour, Chalmers EngineeringMetals, Gothenburg 2001, 19 ppJohan Ahlström and Birger Karlsson: Modelling of heat conductionand phase transformations during sliding of railwaywheels, Wear, vol 253, nos 1-2, 2002, pp 291-300 (revised versionof conference paper)Dr Johan Ahlström (centre) with Professor Ian Hutchings (left)and Professor Birger Karlsson after Johan Ahlström’s successfuldefence of his doctoral dissertation (examination in public) inMarch 2001In the mu2 project, material structures have been soughtthat can better resist the mechanical and thermal loadson railway wheels. These loads originate from regularrolling contact and tread braking and irregular wheelsliding (wheel flats). As previously reported (see thecharmec Triennial Report from Stage 2), 36 castingswith different levels of the micro-alloying elements andwith different forging procedures and heat treatmentsup to the finished railway wheel have been produced inco-operation with Lucchini Sweden (formerly AdtranzWheelset). Test pieces from the wheels with the newx x x x x x x x x xx x x x x x x x x xx x x x x x x x x xx x x x x x x x x xx x x x x x x x x xnS(t 1 )nτ(t 2 )τ(t 1 )32