FH（全硬钢）：是一种通过控制退火温度来提高钢板屈服强度的钢。根据国际通用标准，屈服强度为≥ 550MPa，抗拉强度为≥ 570Mpa。这种材料强度高，伸长率低。适用于浅板形钢板的成型，大大节省了材料的使用。它也是一种各国渴望研发的钢材。国外标准中也描述了具有高强度和良好延伸率的材料。低合金高强度合金（HSLA）用于炼钢中添加强化合金元素，但由于其强度高，在钢铁厂进行。轧制时，增加压下率是有限的。因此，HSLA钢很少用作薄彩色涂层板作为外壳结构（另一个缺点是成本高）。
In the selection of domestic color coated steel plates, users have a vague understanding of the types of steel. At present, most domestic color coated steel plate manufacturers have only one steel grade, that is dc51 (because the hot-rolled plate or hard
rolled coil they purchase is basically one steel grade). Some color coated steel plate manufacturers with hot-dip galvanizing production lines try to produce all hard steel (S550) or high-strength steel (S350, etc.) through hot-dip galvanizing annealing,
but it is very difficult because they have great influence on the quality of substrate The chemical composition cannot be controlled. Therefore, the quality stability is poor, and the poor stability leads to large performance fluctuation, which will
lead to the deterioration of profiled plate.
For buildings, the bearing weight (wind load, snow load, construction personnel and machinery), the design of building span and purlin distance all depend on the strength of steel plates. For color coated and aluminized zinc plates for building maintenance
structures, there are corresponding standards abroad. For example, astm653 and astm792 in the United States, jisg3302 and jisg3321 in Japan, en10215 and en10147 in Europe, etc.
It is divided into CQ (ordinary commercial grade), DQ (general stamping),
HSS (high strength structural steel) and FH (all hard steel) according to the steel type.
CQ (ordinary commercial grade): the most common type of steel used now. Its yield strength before painting is between 260-320mpa. After color coating, if the
substrate is aluminum killed steel, the final strength will be improved, accompanied by the deterioration of elongation. The tensile strength of this steel is between 350-400mpa, and its yield ratio is slightly higher than that of structural steel.
DQ (for general stamping): because the color plates for general construction are roll formed or composite sandwich, the requirements for the stamping performance of materials are not high, so they are rarely used in the construction field (except for
some color plates for doors and windows).
HSS (high strength structural steel): HSS can be divided into 4-5 kinds of steel with different strength according to the European standard. However, since ordinary CQ grade materials can replace HSS steel
with low strength, steel with yield strength of 280mpa and 345mpa are widely used in the market. Compared with ordinary CQ, HSS steel has several advantages: 1. Due to its low yield strength, this steel has good fire resistance and earthquake resistance;
2. For thicker steel plates, it can manufacture large-span arch plates; 3. For general exterior walls and roof panels, it can be appropriately thinner than CQ materials, so as to save material consumption.
FH (all hard steel): it is a kind of steel
that improves the yield strength of steel plate by controlling the annealing temperature. According to the international general standard, the yield strength is ≥ 550MPa and the tensile strength is ≥ 570Mpa. This kind of material has high strength and
low elongation. It is suitable for forming steel plates with shallow plate shape, which greatly saves the use of materials. It is also a kind of steel that countries are eager to research and develop. Materials with high strength and good elongation are
also described in foreign standards. HSLA (low alloy high strength) is used to add strengthening alloy elements in steelmaking, but it is carried out in iron and steel plant due to its high strength. When rolling, increasing the reduction rate is limited.
Therefore, HSLA steel is rarely used as the thin color coated plate as the enclosure structure (another disadvantage is the high cost).
In order to ensure the shape of the final product of color coated steel plate, the strength grade of steel plate,
the shape of profiled steel plate and processing machine are closely related.