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Atmospheric Corrosion-Resistant Steel Plates
In the latter half of the 1950s, Japan introduced the technology of CORTEN. Since then, each of Japan's steel companies has started developing such steel on its own. Sumitomo Metals has also provided atmospheric corrosion-resistant steel under the trade name of CR2. According to the Japanese Industrial Standards (JIS), there are atmospheric corrosion resisting steel for welded structure SMA and superior atmospheric corrosion resisting steel SPA, and SMA has plates for painting (P) and those for non-painting (W). SMI has three kinds of atmospheric corrosion-resistant steels. They are classified into CR2, CR2M and CR2R-H which are equivalent to SMA(P), SMA(W) and SPAH, respectively. As they have been applied to various structures after exposure tests across the country, results will be introduced below. 1. Various steel plates are available as required by any usage. Sumitomo Metals has its own standards equivalent to the Japanese Industrial Standards, in accordance with which SMI is ready to supply atmospheric corrosion-resistant steels of 390N/mm2 to 590N/mm2 classes. They are used in painted or non-painted condition, or with weather-act treatment. In addition, CR2R-H is available as highly atmospheric corrosion-resistant steel. 2. Superb atmospheric corrosion resistance Alloying elements such as Cu, Cr, P, Ni, and Mo are added which are effective for atmospheric corrosion resistance. Excellent atmospheric corrosion resistance of such kind of steels has also been proven by long-time exposure tests across the country. 3. Excellent weldability Though special elements such as Cu and Cr are added, these steel plates maintain excellent weldability because C%, Ceq%, and PCM% are controlled. In addition, if required, appropriate atmospheric corrosion-resistant steel is supplied in each case complying with such needs as reduced pre-heating and large heat input in welding. 4. Excellent workability Compared with steels for welded structures, these steel plates are larger in elongation and better in workability in spite of their high yield point. They are also good in hot workability and gas cutting property. 5. Excellent paintability Rust spreads so slowly under the paint film over atmospheric corrosion-resistant steel plates for painting, CR2 and SMA(P), that such paint film has a long life. 6. Various chemical treatments and Weather Act® applied besides bare use Various treatments such as chemical ones and Weather Act are applicable to CR2M and SMA(W). |
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