Role of grain boundary character on hot corrosion and liquation cracking in a Ni base superalloy and austenitic stainless steel
Enhancement in the properties and performance of materials has always been the quest of the materials scientists and engineers. In this context, grain boundary engineering (GBE) has emerged as an alternative attractive approach (as it does not require modification of the chemical composition) to improve bulk polycrystalline properties such as the resistance against corrosion, oxidation, segregation, embrittlement, liquation cracking, creep, fatigue, and fracture. The basic philosophy of GBE is to optimize the grain boundary character distribution (GBCD) and their network by increasing the proportion of the so-called ‘special boundaries’ (SBs). SBs are those that have relatively better properties when compared to the random high-angle grain boundaries (HAGBs) and are often described in terms of the coincidence site lattice (CSL) model. GBE microstructure is achieved through strain-annealing or strain-recrystallization processing in face centered cubic metals and alloys with medium and low stacking fault energy. In this talk, I present the microstructural evolution during GBE processing of a Nickel base superalloy and an austenitic stainless steel. I will discuss about microstructural parameters for identifying the GBE microstructure. The response of the GBE processed alloys to hot corrosion and liquation cracking in the heat affected zone (HAZ) are analyzed and correlated to the GB character.
Prof. V. Subramanya Sarna
Department of Metallurgical and Materials Engineering
Indian Institute of Technology Madras
IIT P.O., Chennai 600 036
INDIA
| Phone | +91 44 2257 4774 |
| Prof. V. Subramanya Sarma | |
| Http | Prof. V. Subramanya Sarma |
| Department of Metallurgical and Materials Engineering |