According to the characteristics of the two-phase structure, by properly controlling the chemical composition and heat treatment process, the excellent toughness and weldability of austenitic stainless steel are combined with the higher strength and chloride stress corrosion resistance of ferritic stainless steel, making duplex stainless Aço Um tipo de aço que combina excelente resistência à corrosão, alta resistência e fácil processamento e fabricação. Their physical properties are between austenitic stainless steel and ferritic stainless steel, but closer to ferritic stainless steel and carbon steel. The resistance to chloride pitting and crevice corrosion of duplex stainless steel is related to the content of chromium, molybdenum and nitrogen. Its resistance to pitting and crevice corrosion can be similar to that of 316 stainless steel, or higher than that of stainless steel for seawater, such as 6%MO austenitic stainless steel. All duplex stainless steels are significantly more resistant to chloride stress corrosion cracking than 300 series austenitic stainless steels, and their strength is also much higher than austenitic stainless steels, while showing good plasticity and toughness.

O aço inoxidável duplex geralmente pode ser dividido em quatro categorias:

Chemical composition The main alloying elements of duplex steel are Cr, Ni, Mo and N. Among them, Cr and Mo are used to increase the ferrite content, while Ni and N are austenite stabilizing elements. Alguns graus de aço também têm elementos como Mn, Cu e W. Cr, Ni e Mo podem melhorar a resistência à corrosão. Its resistance to pitting and crevice corrosion is particularly good in chloride-containing environments.

Vantagens do aço inoxidável duplex

1. Comparado com austenítico aço inoxidável

2. Comparado com o aço inoxidável ferrítico, as vantagens do aço inoxidável duplex são as seguintes:

1) The comprehensive mechanical properties are higher than those of ferritic stainless steel, especially plastic toughness. Não é tão sensível à fragilidade quanto o aço inoxidável ferrítico.

4) O desempenho da soldagem é muito melhor que o aço inoxidável ferrítico. Geralmente, não é necessário pré -aquecimento antes da soldagem e nenhum tratamento térmico é necessário após a soldagem.

5) A faixa de aplicação é mais ampla que a do aço inoxidável ferrítico.

Aplicativo

Devido à alta resistência do aço duplex, geralmente pode salvar materiais, como reduzir a espessura da parede do tubo. Pegue o SAF2205 e o SAF2507W como exemplos. SAF2205 is suitable for use in chlorine-containing environments. This material is suitable for oil refining or other process media mixed with chlorides. SAF2205 is particularly suitable for heat exchangers that use chlorine-containing aqueous solutions or slightly salty water as cooling media. This material is also suitable for diluted sulfuric acid solutions and pure organic acids and their mixtures. For example: oil pipes in the oil and gas industry: crude oil desalination in refineries, sulfur-containing gas purification, wastewater treatment equipment; cooling systems using slightly salty water or chlorine-containing solutions.