Effects of Si and Mn Contents on the Tensile Properties of Normalized Medium Carbon Steels

Abstract

Effects of Si and Mn additions on the tensile properties of medium carbon steels have been investigated to assess the utility as non-ardened high strength steels. Results concerning 0.3%C-Si-Mn steels are summarized as follows:
(1) The tensile strength increases 9.5 kg/mm² per 1% of Si+Mn up to the transitional value of 1.7%Mn, over which the strength is raised only with a rapid fall of elongation due to lowtemperature transformation.
(2) The larger the Si/Mn ratio in the steels up to about 6, the higher strength can be obtained with little decrease of elongation, so far as the steels keep ferrite-pearlite structure.
(3) The limit to strengthen these steels holding at least 18% elongation is estimated to about 90 and 70 kg/mm² for tensile and yield strengths respectively. Concerning with 0.47%C-Si-Mn steels,
(4) The larger the Si/Mn ratio up to about 2, the higher elongation can be obtained.
(5) The limit to strengthen these steels holding at least 18% elongation is estimated to about 977and 63 kg/mm² for tensile and yield strength respectively.