The influence of various alloing elements on the low temperature transition properties of low-manganese high-strength steel, standard composition of,0·28% C. 2·00% Mn,0·50% Cr, and 0·30% Mo, tempered sorbitic structure of HRC 32±1 hardness, were tested by V-notch Charpy inpact test.
Result obtained were as follows:
1. Transition temperature in this steel became very lower when carbon content fell below 0·15%, but in carbon content range of 0·20-0·35% steel, it did not follow that transition properties were always improved as carbon content lowering.
2. Addition of such elements, silicon, chromium, tungsten, titanium, titanium-boron, and copper in this steel, were harmful to low-temperature transition properties. Especially, it was desired that such elements, silicon, chromium and copper in this steel were as fall as possible.
3. Both elements, molybdenum and vanadium were effective, additional elements for lowtemperature transition properties. Most effective content of these elements were 0·5-0·6%. molybdenum and about 0·1% vanadium in this steel.