| The present study was investigated the effect of rolling finishing temperature, slab reheating temperature and manufacturing process on the high temperature strength characteristic of 0.1%C-1%Mn 0.5%Mo steel containing Ti and B respectively. In the specimen containing Ti was obtained a little bainite in matrix of ferrite and pearlite phase, while, the specimen containing B was obtained boride and martensite phase. With increase of rolling finished temperature, in the A specimen containing Ti, bainite phase was increased and in the B specimen containing B, martensite lath was coarsened. In the two specimens treated by air cooling or quenching and tempering after rolling, with increasing of test temperature, yield strength and yield strength ratio decrease slowly, and rapidly decreased at over 600℃, but Y.S ratio at 600℃ appears higher value than 70%. In the B specimen, yield and tensile strength, Y.S ratio of specimens tempered after air cooling appears higher than quenching and tempered, but lower than air cooling specimens. With increase of rolling finished temperature, Y.S ratio of A and B specimens increased at RT and 600℃, but, when rolling finished temperature become over 900℃, Y.S and T.S of B specimens are decreased and A specimens are rapidely increased, while, with increased of slab reheating temperature, Y.S and T.S of A specimens was unchanged, but B specimens were decreased and Y.S ratio of A and B specimens increased. In the A specimen, Y.S ratio is strongly controlled by the volume fraction of secondary phase, but strength is affected by other factors except the volume fraction of secondary phase. |
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