Ultra fast annealing of high-strength low-alloy steels (HSLAS)

Abstract

Consulta en la Biblioteca ETSI Industriales (9087)

[EN] The ultrafast heat treatment has been compared with a traditional one, (salt bath annealing followed by water quenching) in order to reveal more clear the differences and to clarify advantages and disadvantages of the ultra fast heating. Ultra fast heating is expected also to suppress the recrystallization processes which may trigger the interaction between the recrystallization and phase transformation and to create ultra fine grain structures and specific crystallographic textures. For this, three types of cold rolled steel with the same chemical composition but different phases composition have been studied. The first one called ¿A¿ is constituted of ferrite + tempered martensite and it has been annealed at ~150ºC/s (salt bath) and ~400ºC/s (Joule effect). The second one, ¿B¿ is constituted of ferrite + pearlite and it has been annealed at ~150ºC/s (salt bath) and ~1400ºC/s (Joule effect). The third one, ¿C¿ is constituted of ferrite + pearlite as well and it has been annealed at ~10ºC/s and ~3000ºC/s. All the samples were annealed at different critical austenitic temperatures and then water quenched. The microstructure has been studied by means of optical and SEM microscopy and the mechanical properties by means of micro hardness and micro tensile tests.