Optimalizace délky izotermické prodlevy při výrobě ADI

Optimization in Dwell Length of ADI Isothermal Transformation

journal article - other

en

Austempered ductile iron (ADI) is usually obtained by isothermal heat treatment. Owing to its excellent mechanical as well as technological properties, ADI belongs among prospective structural materials. Recently it is applied also to castings for dynamically loaded machine details, e.g. gear and traversing wheels, crankshafts of motor-cars, vans and trucks, swivel pins, rail brakes and pressure pipes in oil industry. Microstructure and mechanical properties of ADI can be substantially influenced by the condition of heat treatment. While the austenitization conditions play only marginal role, the conditions of isothermal transformation, i.e. transformation temperature and the dwell at it, influence the resulting structure of ADI and consequently its mechanical properties very substantially. Present paper is devoted to the study how the dwell of isothermal transformation in the range of 2 minutes to 9 hours influences the structure as well as the static and fatigue properties of unalloyed ADI transformed at temperature of 380 °C.

Izotermicky zušlechtěná litina s kuličkovým grafitem (ADI) se vyrábí pomocí izotermického zpracování. Tento materiál má výborné mechanické i technologické vlastnosti a díky nim se zařadil mezi konstrukční materiály. Nedávno začala být používána také pro dynamicky namáhané součásti, např. ozubená kola, vačkové hřídele atd. Mechanické vlastnosti a mikrostruktura tohoto materiálu je ovlivněna podmínkami tepelného zpracování. Zatímco podmínky Austenitizace nemají výrazný vliv na výslednou mikrostrukturu, podmínky izotermické transformace výslednou mikrostrutkuru a tedy i mechanické vlastnosti ovlivňují zásadním způsobem. V tomto příspěvku byl studován vliv délky izotermické prodlevy v rozsahu 2 minuty až 9 hodin na výslednou mikrostrukturu a na statické mechanické vlastnosti a únavové vlastnosti nelegované ADI transformované při teplotě 380°C.

Austempered ductile iron (ADI) is usually obtained by isothermal heat treatment. Owing to its excellent mechanical as well as technological properties, ADI belongs among prospective structural materials. Recently it is applied also to castings for dynamically loaded machine details, e.g. gear and traversing wheels, crankshafts of motor-cars, vans and trucks, swivel pins, rail brakes and pressure pipes in oil industry. Microstructure and mechanical properties of ADI can be substantially influenced by the condition of heat treatment. While the austenitization conditions play only marginal role, the conditions of isothermal transformation, i.e. transformation temperature and the dwell at it, influence the resulting structure of ADI and consequently its mechanical properties very substantially. Present paper is devoted to the study how the dwell of isothermal transformation in the range of 2 minutes to 9 hours influences the structure as well as the static and fatigue properties of unalloyed ADI transformed at temperature of 380 °C.

ADI, isothermal transformation, transformation dwell, mechanical properties

2003

25.11.2003

1429-6055

Zeszyty naukowe politechniki Opolskiej seria Mechanika

76

290

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