Objetivo CONTROL OF AUSTENITE GRAIN SIZE AT HIGH TEMPERATURES (< 1000 CELSIUS DEGREES) PREVAILING IN THE WELD HEAT AFFECTED ZONE (HAZ) IS BECOMING OF INCREASING INTEREST TO FABRICATORS OF LARGE SCALE STRUCTURES, E.G. PIPELINES AND OIL RIGS, BECAUSE A TREND TOWARDS SPECIFICATION OF INCREASINGLY STRINGENT HAZ TOUGHNESS REQUIREMENTS. ALLIED TO THE GREATER USE OF HIGH DEPOSITION RATE WELDING PROCESSES THESE SPECIFICATIONS INDICATE A NEED FOR STEELS IN WHICH HAZ MICROSTRUCTURE CAN BE CONTROLLED. ONE ELEMENT IN THIS DEGREE OF CONTROL IS THE RESTRICTION OF GRAIN GROWTH WHICH OCCURS DURING THE WELD THERMAL CYCLE. THIS REQUIRES THE PRESENCE OF A FINE DISPERSION OF STABLE PARTICLES WHICH GREATLY RETARD AUSTENITE GRAIN GROWTH. WHILST THE PRINCIPLES OF THIS METHOD OF CONTROL ARE WELL KNOWN, IMPLEMENTATION TO DATE HAS MADE USE OF DISPERSIONS OF FINE TIN PARTICLES. THE USE OF TIN, AS IN TI-AL STEELS, CAN PLACE A NUMBER OF RESTRICTIONS ON STEEL PROCESSING AND GENERALLY REQUIRES THE STEEL TO BE CONTINUOUSLY CAST. FURTHERMORE, THE EXTENSION OF THIS TECHNIQUE TO OTHER MICROALLOYED STEELS, PARTICULARLY THOSE CONTAINING NIOBIUM, HAS PROVED DIFFICULT. THIS IS BECAUSE IT HAS BEEN DIFFICULT TO CONTROL, TO THE REQUIRED DEGREE, PRECIPITATE SIZE AND DISTRIBUTION IN THE NIOBIUM AND-OR VANADIUM STEELS TREATED WITH TITANIUM BECAUSE COMPLEX NBTIX OR VTIX (X MAINLY N) COMPOUNDS ARE FORMED WITH APPRECIABLY DIFFERENT SOLUBILITIES TO TIN. THE MORPHOLOGY OF THE COMPOUNDS IS ALSO COMPLEX AND LITTLE DATA EXIST REGARDING THE CHANGES NECESSARY TO PRODUCE FINE STABLE DISPERSIONS AS A FUNCTION OF PROCESSING FROM SLAB TO PLATE. ONE ASPECT OF THE PROPOSED RESEARCH IS, THEREFORE, TO DEVELOP A GREATER UNDERSTANDING OF THE PROCESSING PARAMETERS, SUCH AS POST SOLIDIFICATION COOLING RATES, SLAB SOAKING TEMPERATURES AND ROLLING SCHEDULES, WHICH WILL LEAD TO THE FORMATION OF PARTICLE DISTRIBUTIONS WITH CHARACTERISTICS SUITABLE FOR CONTROL OF HAZ AUSTENITE GRAIN SIZE IN A RANGE OF NIOBIUM OR VANADIUM TREATED STEELS. CENTRAL TO THIS PARTICULAR ASPECT OF THE RESEARCH PROPOSAL IS THE DEVELOPMENT OF A GENERAL THERMODYNAMIC MODEL WHICH CAN BE USED TO PREDICT THE PARTICLE AND MATRIX COMPOSITIONS FOR MULTICOMPONENT MICROALLOYED STEELS CONTAINING TITANIUM AND OTHER STRONG NITRIDE FORMERS. HAZ SIMULATION TECHNIQUES WILL BE USED TO STUDY THE DEGREE OF AUSTENITE GRAIN SIZE CONTROL ACHIEVED IN SAMPLES WITH A VARIETY OF DISPERSIONS. LIMITED TESTING WILL ALSO BE PERFORMED ON PARTICULARLY PROMISING SAMPLES. Programa(s) ECSC-STEELRES 6C - Medium-term orientation (ECSC) "steel research in relation to the General Objectives for Steel", 1981-1985 Tema(s) Data not available Convocatoria de propuestas Data not available Régimen de financiación Data not available Coordinador Swinden Technological Centre Aportación de la UE Sin datos Dirección Moorgate S60 3AR ROTHERHAM Reino Unido Ver en el mapa Coste total Sin datos
