Simplified Notch Toughness-Tests on Mn-Si High Tensile Steels

Abstract

Customary transition-temperature tests generally require too much material and are very laborious. In a previous report, one of the authors suggested a simple testing method to evaluate the notch toughness of materials, so-called simplified notch toughness test which was based upon the experimental results of structural mild steels. This method uses the properties that the values ofψ(ratio of true stress to strain at the maximum load in atensile test), ψ', ψ and ψ', which are described in the present paper, are constant within the temperature range of -80°C to 100°C and that the material having the smaller values of ψ, ψ', ψ or ψ' shows the lower transition temperature.
The purpose of this report is studying the applicability of above mentioned simplified notch toughness test on various structural high tensile steels.
The test results obtained were almost the same with that shown in the structural mild steels except, the temperature range in which the value of ψ or ψ' is constant as seen in Fig. 9 and Fig. 10. Moreover authors confirmed that ψ or ψ' obtained by room temperature test can be adopted as an index of the notch toughness of high tensile steels.