| abstract |
The present invention provides a steel material for a welded structure of 490 MPa class, which has a high yield point and a high weldability due to a low Pcm, and has good acoustic anisotropy and productivity. The composition of steel is as follows: C: 0.05 to 0.15%, Si: 0.02 to 0.50%, Mn: 0.3 to 2.0%, P: 0.010% or less, S: 0.007% or less, Nb: 0.005 to 0.024% Ti: 0.003-0.030%, Al: 0.060% or less, B: 0.0003% or less, N: 0.0010-0.0060%, Pcm is 0.27 or less, and the average aspect ratio of the prior austenite grains is 1.6- The steel is manufactured by controlled rolling and controlled cooling under appropriate conditions. [Selection] Figure 1 |