TITLE:
Optimization of the Annealing Parameters for Improved Tensile Properties in Cold Drawn 0.12 wt% C Steel
AUTHORS:
Nurudeen A. Raji, Oluleke O. Oluwole
KEYWORDS:
Annealing; Steel; Cold Drawn; Soaking Time; Strength; Optimization
JOURNAL NAME:
Engineering,
Vol.5 No.11,
November
6,
2013
ABSTRACT:
Drawn low carbon steel is characterized by brittle
fracture. These defects are associated with the poor ductility and high strain
hardening due to the cold work. There is a need therefore to
determine optimum heat treatment parameters that could ensure improved
toughness and ductility. Determining the optimum annealing parameters ensures valued
recrystallization and also minimizes grain growth that could be detrimental to the
resulting product. 40% and 55% cold drawn steels were annealed at temperatures
500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval
of 10 minutes to identify the temperature range and soaking time where optimum
combination of properties could be obtained. Tensile test and impact toughness
experiments were done to determine the required properties of the steel. Polynomial
regression analysis was used to fit the properties relationship with soaking
time and temperatures and the classical optimization technique was used to
determine the minimum soaking time and temperature required for improved
properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain
size of 44.7 mm can be considered to be the optimum annealing treatment for the
40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.