Method for producing H-shaped steel
The present invention relates to a method for producing H-shaped steel using a slab or the like having a rectangular cross-section as a material, for example. Provided is a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step. A slab material whose ratio of slab width to slab thickness is equal to or more than 6.0 and equal to or less than 7.7 is used as a material to be rolled. In a rolling mill a plurality of calibers having projections may be provided to shape the material to be rolled. The projections may have a height of 100 mm or more, and the tip of the projections may have an angle of equal to or more than 25° and equal to or less than 40°.
1. A method for producing H-shaped steel,
the method comprising:
a rough rolling step of shaping a material to be rolled in one or a plurality of passes, the material to be rolled being a slab material having a width and a thickness, where a ratio of the width to the thickness is equal to or more than 6.0 and equal to or less than 7.7, the shaping of the material to be rolled performed by a rolling mill having a plurality of calibers engraved thereon to shape the material to be rolled, a number of the plurality of calibers being four or more, the plurality of calibers having a first caliber and a second caliber, each including a projection that splits vertically the material to be rolled in a width direction, the projection formed in the first caliber having a height of 100 mm or more, and the projections formed in the first caliber and the second caliber having a tip angle of 40° or less, respectively;
an intermediate rolling step of reverse rolling the material after the rough rolling step to obtain an intermediate material; and
a finish rolling step of shaping the intermediate material to the H-shaped steel.
2. The method for producing H-shaped steel according to claim 1 , wherein the slab material has a slab width of 1800 mm or more and a slab thickness of 300 mm or more at a start of shaping in the first caliber.
3. The method for producing H-shaped steel according to claim 1 , wherein the slab material has a slab width of 1200 mm or more and a slab thickness of 250 mm or more at a start of shaping in the first caliber.
4. The method for producing H-shaped steel according to claim 1 , wherein the tip angle of the projections formed in the first caliber and the second caliber is equal to or more than 25° and equal to or less than 35°, respectively.
5. The method for producing H-shaped steel according to claim 1 , wherein;
in the second caliber and subsequent calibers among the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with caliber peripheral surfaces in the rough rolling step; and
in a third caliber and subsequent calibers among the plurality of calibers, in addition to the reduction, a step of sequentially bending divided parts formed by the splits is performed.
6. The method for producing H-shaped steel according to claim 1 , wherein the first caliber is provided with relief portions extending in a direction of being distanced from the material to be rolled at a material-to-be-rolled entry side of a side-wall portion of the first caliber that is adjacent to a side surface of the material to be rolled while the rough rolling step is being performed.
7. The method for producing H-shaped steel according to claim 6 , wherein the relief portions have a curved shape in which an inner surface of the relief portions, which is facing with the material to be rolled, is curved away from the material to be rolled, and a curvature radius R of the curved shape is 400 mm or less.
8. The method for producing H-shaped steel according to claim 1 , wherein;
the tip angle of the projections formed in the first caliber and the second caliber is equal to or more than 25° and equal to or less than 35°, respectively;
in the second caliber and subsequent calibers among the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with caliber peripheral surfaces in the rough rolling step; and
in a third caliber and subsequent calibers among the plurality of calibers, in addition to the reduction, a step of sequentially bending divided parts formed by the splits is performed.
9. The method for producing H-shaped steel according to claim 1 , wherein the tip angle of the projections formed in the first caliber and the second caliber is equal to or more than 25° and equal to or less than 35°, respectively, and
the first caliber is provided with relief portions extending in a direction of being distanced from the material to be rolled is formed at a material-to-be-rolled entry side of a side-wall portion of the first caliber that is adjacent to a side surface of the material to be rolled while the rough rolling step is being performed.
10. The method for producing H-shaped steel according to claim 1 , wherein;
the tip angle of the projections formed in the first caliber and the second caliber is equal to or more than 25° and equal to or less than 35°, respectively;
the first caliber is provided with relief portions extending in a direction of being distanced from the material to be rolled at a material-to-be-rolled entry side of a side-wall portion of the first caliber that is adjacent to a side surface of the material to be rolled while the rough rolling step is being performed;
the relief portions have a curved shape in which an inner surface of the relief portions, which is facing with the material to be rolled, is curved away from the material to be rolled; and
a curvature radius R of the curved shape is 400 mm or less.