1.What standards do the Chinese and European standards for cold-rolled coils adopt respectively? What are the essential differences between the two standard systems?
The naming logic differs: The Chinese national standard GB/T 708-2006 uses yield strength as the grade designation (e.g., Q195, Q235), which makes it difficult to distinguish from other steel grades. GB/T 5213-2008 and the European standard EN 10130-2006 have largely the same designation rules, both using the DC series naming convention.
The standard positioning differs: The European standard system emphasizes "formability" grading (DC01-DC07 progressively improving stamping performance), while the Chinese national standard system has two parallel systems: "strength priority" (Q series) and "formability priority" (DC series).
2.How do the Chinese national standard (GB) and European standard (EU) designations correspond? Which GB designation does DC01 correspond to?
In Chinese national standards, DC01 can correspond to DC01 in GB/T 5213 or Q195/Q215 in GB/T 708. However, there are slight differences in their performance; specific technical parameters should be consulted during procurement.
Regarding structural steel, European standard S235JR is equivalent to Chinese standard Q235B.
3.What are the key differences between Chinese national standards and European standards in terms of mechanical properties and chemical composition?
The chemical composition requirements are basically the same, with European standards not imposing mandatory regulations on aluminum content.
The yield strength range differs slightly: the lower limit of the Chinese standard is 130 MPa, while the lower limit of the European standard is 140 MPa; the upper limit of the Chinese standard is 260 MPa, while the upper limit of the European standard is 280 MPa.
The differences are more pronounced in deep-drawing series: taking DC04 as an example, the yield strength of both the Chinese and European standards is 120-210 MPa, but the elongation requirement is slightly higher in the Chinese standard.
4.What are the differences between Chinese national standards and European standards in terms of surface quality grading and surface finish?
The Chinese national standard classifies surface quality into three levels (FB/FC/FD), while the European standard classifies it into two levels (A/B).
The European standard provides a more detailed classification of roughness, dividing it into three different roughness grades: g, m, and r. Specific roughness values should be referred to the original standard text.
The German standard DIN 1623-1 uses O3 (general) and O5 (better) surface quality classifications and follows the European standard's surface finish marking method. For example, ST12O3r indicates a general surface quality, or a rough, textured surface.
5.What are the differences in dimensional tolerances between Chinese national standards and European standards? How are material certificates mutually recognized?
Material Certification Content: Both standards require a quality certificate, including furnace number, coil number, chemical composition, and mechanical properties. However, the European standard places greater emphasis on CEV (carbon equivalent) and weldability parameters.
Mutual Recognition Principle: There is no automatic mutual recognition between Chinese and European standards; confirmation requires a technical equivalence assessment. In procurement practice, DC01 and Q195/Q215 can be approximated in general applications, but the following should be noted:
For high-requirement applications such as automotive steel sheets and appliance panels, direct substitution is not recommended; suppliers should be required to produce according to specified standards.
When substituting, performance parameters (yield strength, tensile strength, elongation) should be the core comparison criterion, not just the grade.
Acceptance Recommendations: When procuring internationally, it is recommended to clearly specify the applicable standard and version number (e.g., GB/T 5213-2008 or EN 10130:2006) in the contract and require a quality certificate for the corresponding standard to avoid standard disputes upon delivery.