On the Preliminary Research for the Development of H.T.60 (Report 3)

Abstract

Based on the rusults of the investigation reported in the 2nd report, four heats of the Vanity+Ni +Cr+Mo type as the high tensile structural steel with tensile strength over 60kg/mm² (H.T. 60) were melted in the 20 ton electric basic furnace, and their mechnical properties and weldability were examined in detail.
1. It is needed for getting satisfactory results that carbon content is kept about 0.13 and 0.15% for as rolled and normarized plates, respectively. Otherwise materials show much less tensile strenght or less elongation. Other alloying elements must be lowered to guarantee weldability of plates.
2. All steels tested are warranted for V-notch Charpy test results.
3. From the view points of hardenability and crack sensitivity, it is recommended that the respective Ceq are lower than 0.45 and 0.35.
4. Maximum hardeness below 350Hv in H.A.Z. of I.I.W. test guarantees the resistance to the generation of crack of Kinzel and Kommerel tests, and the I.I.W. maximum hardness plus the hardness of parent metal as low as possible under 550Hv guarantees no breaking at the bending angle of 120 dergee of Kommerel test.