Effect of Carbon Element on Duplex Stainless Steel Pipe
Effect of carbon element on duplex stainless steel pipe. Carbon is one of the main elements of industrial steel. The performance and organization of steel are largely determined by the content of carbon in steel and its distribution, especially in stainless steel. Carbon in the stainless steel in the organization of the main performance in two aspects, on the one hand carbon is stable austenite elements, and the role of a large degree (about 30 times the nickel), on the other hand because of the affinity of carbon and chromium large, with chrome formation - series of complex carbides. Therefore, from the strength and corrosion resistance of the two aspects of performance, the role of carbon in stainless steel is contradictory.
Recognizing the law of this influence, we can choose from different requirements of the use of different carbon content of 314 stainless steel pipe.
For example, the most widely used in industry, but also the minimum of stainless steel - 0Crl3 ~ 4Cr13 the five steel standard chromium content of the provisions of 12 to 14%, that is, carbon and chromium to form chromium carbide factors into account before The purpose of which is to make carbon and chromium combined into chromium carbide, the solid solution in the chromium content is not less than 11.7% of the minimum chromium content.
On the five steel grades because of different carbon content, strength and corrosion resistance is also different, 0Cr13 ~ 2Crl3 steel corrosion resistance is better but the strength is lower than 3Crl3 and 4Cr13 steel, used for manufacturing structural parts, after two steel grades due to higher carbon and can get high strength for the manufacture of springs, knives and other requirements of high strength and wear parts. Also, to overcome the intergranular corrosion of 18-8 chrome-nickel stainless steel, the carbon content of the steel can be reduced to less than 0.03%, or an element (titanium or niobium) having a greater affinity than chromium and carbon can be added so as not to form carbon chromium. And then when the high hardness and wear resistance to become the main requirements, we can increase the carbon content of steel at the same time to properly improve the chromium content, so that both meet the hardness and wear resistance requirements, but also both - Corrosion function, used as a bearing for bearings, measuring and cutting with stainless steel 9Cr18 and 9Cr17MoVCo steel, carbon content as high as 0.85 ~ 0.95%, because of their chromium content is also increased accordingly, so still ensure the requirements of corrosion resistance.
In general, the current industrial stainless steel pipe carbon content is relatively low, most of the 904L stainless steel pipe carbon content between 0.1 to 0.4%, acid-resistant steel is 0.1 to 0.2% of carbon content. Stainless steel with a carbon content greater than 0.4% represents only a small fraction of the total number of steel grades, because stainless steel is always resistant to corrosion under most conditions of use. In addition, the lower carbon content is also due to certain process requirements, such as easy welding and cold deformation.