Zofia Niemczura
Arcelormittal Global R&D, USA
Title: Heat resistant engineering materials for industrial application
Biography
Biography: Zofia Niemczura
Abstract
A number of new generation materials such as nonferrous and ferrous-alloys, superalloys, steels, ceramics, polymers, composites, etc., designated for service in the extreme environments have been developed. Some of this materials provide the protection/insulation from heat (e.g. ceramics, polymers) and some offer an outstanding high temperature mechanical properties for the demanding aerospace, energy, and manufacturing industries where the service condition often includes mechanical load, thermal shock, vibrations, and oxidation/corrosion in temperature much above 1000℃. Most industries still rely on ferrous and nonferrous alloys as the main engineering materials for a high temperature application because of its unique combination of strength, creep resistance, resistance to oxidation/chemical attack, and a good thermal conductivity during service. Moreover, the availability and price of most heat resistant steels and alloys make them a preferred industrial material for a high temperature application.
rnA metallurgical study of a wide variety of manufacturing components made of a Fe-, Ni-, and Co-base heat resistant alloys has been performed in the past years. The structural changes due to a long exposure to service temperature >1000℃, heavy load, vibration, and thermal stress have been carefully analyzed. In general, most of heat resistant steels and alloys deteriorate (and eventually fail) during service due to unfavorable microstructure changes such as: decomposition of carbides or other “reinforcing” phases, precipitation of the detrimental phases, phases coalescence and growth, dendrites recrystallization, oxidation and chemical attack on grain boundaries and the alloy depletion in Cr. It was also found that the microstructural changes are associated with not fully recognized changes of a certain physical properties, mainly magnetic, of the alloy. Since the microstructural and magnetic changes are proportional, using the magnetizm to evaluate the current metallurgical condition of the heat resistant equipment parts is very promising.