5　Choice of Technology Parameter and Type of Continuous Casting Machine

5.1　Choice of Strand Section

5.1.1　The strand section shall be selected according to the mill composition，variety and specification of rolled products as well as reduction ratio required by different steel grade and shall meet the requirement for obtaining the reasonable economic benefit from steelmaking，continuous casting and rolling.With satisfaction of variety and quality of rolled products，the rolling in one heating is preferably adopted.

5.1.2　The type of continuous casting machine can be divided as per table 5.1.2.

5.1.3　The Min.section of strand shall be in accordance with following regulations:

1　The side length of normal carbon billet shall not be less than 120mm.

2　The side length of special steel billet shall not be less than 130mm.

3　The diameter of round billet shall not be less than 140mm.

4　The thickness of slab shall not be less than 140mm.

5　The thickness of thin slab shall not be less than 50mm.

5.1.4　The range from Min.section to Max.section of the strands for each caster shall not be oversize.

5.1.5　The strand specification of each caster shall be as simple as possible under the preconditions that the product requirement is satisfied.

5.1.6　When designing the type of caster common for slab and billet，the production of slab shall be prevailing，and the billet shall be produced in a little.The thickness of billet shall not exceed the maximum thickness of slab.

5.1.7　The caster supplying the blank to H section mill shall use the near-net-shape strand as the blank，and the caster supplying the blank to small H section mill can use the bloom as the blank.