Abstract
Using four Japanese rimmed steels, the authors have done torsional test of round bars within the temperature range of -80°C to+200°C and compared these results with the notch toughness investigated by Charpy and notched slow bending test using U and V type standard Charpy syecimens.
In order to discuss the judgment of the uotch toughness of materials from torsional testing results, we abopted the criterion,
ψ=breaking twisting moment/breaking twisting angle (see Fig.8)
Then we found the notable : (a) the valve of ψ remained constant within the experimental temperature range (-80°C-+100°C), being independent of testing temperature (see Fig. 7) and (b) material of which the value of ψ is lower shows the lower transition temperature (see Fig.9).
Consequently, it could be said that the notch toughness of material may be specified by the value of room temparature as well as by the value of ψ and Φ at room temperature in tensile and notch slow behding test respectively.
