1. Tin Plate Sheet Coil are roughly consistent in various Countries and more reasonable and clear points:
(1) SPTE is defined low-carbon cold with a thickness of 0.14~0.49mm.
Rolled tin plate SPTE is called cold rolled tin plated steel sheet, which is commonly known as tinplate;
(2) It is stipulated that Grade A tin with a purity of 99.85% or more is used as one of the raw materials;
(3) The dimensional tolerances of SPTE are specified as -0, +3mm;
(4) The allowable maximum values of thickness tolerances and Tin Plate Sheet Coil shape deviations (such as slanting, side wave, mid-wave, warpage, etc.) are generally the same;
(5) It is stipulated that qualified products should be able to be printed on the entire board of Tin Plate Sheet Coil;
(6) All stipulated a uniform tin plating step and the corresponding minimum allowable tin plating. Namely: Steps: 1.1, 1.7 (1.5), 2.2 (2.0), 2.8, (4.0), (5.0), 5.5, 8.4, 11.2g /m2 and the corresponding minimum allowable value;
(7) All stipulate a unified measurement and testing method for the degree of quenching and tempering (testing the surface Rockwell hardness HR30T or HR15T), and its grade division and marking method, such as T 52, T 54, T 57, T 61, T 64 , DR8, DR9, DR9M and so on.
2. All standards of Tin Plate Sheet Coil are vague:
(1) Try to avoid the characteristics and composition of the steel base (original board) (the strange thing is that there is often a composition table when a large number of formal supplies);
(2) The requirements, indicators, and inspections for surface properties, features, defects, etc. are as little as possible;
(3) There are subtle differences in the deviation of the mechanical properties of the thin plate (first simplify it to a degree of quenching and tempering), and the description of each standard.
The above three points are all related to the corrosion resistance and processing resistance of tinplate, and are one of the main contents that need to be further specified in detail through the additional document clauses of the supply and demand contract. This is because:
First, the strengths and weaknesses of the steel base composition (including its processing methods), especially if the restrictions on the content of certain harmful non-metals and metals are not in place, the corrosion resistance of the sheet and the subsequent electroplating reflow, The formation of a good alloy layer, and good mechanical properties (processing resistance, etc.) are impossible to talk about.
Second, the surface characteristics, it contains three aspects, namely: ① various surface defects (their definition and causes, see "Japan Iron and Steel Association Guide ISIJ T R009" for details) tolerable limit; ② surface roughness , Oil film amount, oxide film amount, surface chromium content, etc. requirements and numerical limits; ③ Specific expressions and agreements on printability.
If the above three points are not stipulated in the annex to the agreement, problems will inevitably arise in the application of tinplate.
Third, the deviation of the quenching and tempering degree is too large, which is only one of the signs of poor mechanical properties and unevenness (the curvature of the garden is large and sometimes small), and sometimes the Lǜder effect occurs, that is, the cans are made into a circle. Time rises along the circumference of the garden.
It can be seen that if there are no additional documents in the supply and demand contract to stipulate the needs of the buyer in the above three aspects and other aspects, then the quality of the future canning will not be based on science but on luck. This is not serious. It is also an unfair relationship.