Stainless steel flange in industrial application are actually exist several or even dozens of elements at the same time, when several elements coexist in stainless steel flange this unity, their impact is much more complicated than single exists, because in this case not only to consider the elements themselves, and pay attention to the mutual influence between them, so the organization of the stainless steel flange is determined by the influence of various elements combined.
1, chromium in stainless steel flange
Decided to stainless steel flange sex there is only one element of the genus, and this is the chromium, each kind of stainless steel flange contain a certain amount of chromium. To date, there has been no do not contain chromium stainless steel flange. Chromium is a stainless steel flange performance of the main elements of decision, the fundamental reason is that after adding chromium alloy elements into the steel, its internal contradiction movement to the aspects of development in the resistance to corrosion damage.
2, carbon duality in the stainless steel flange
Carbon steel is used in industry, one of the main elements of the performance of the steel and organization to a large extent depends on the form of carbon content in steel and its distribution, the influence of the carbon is particularly significant in the stainless steel flange. Carbon in the stainless steel flange on the influence of the organization is mainly manifested in two aspects, on the one hand, carbon austenitic elements are stable, and the role of a large (about 30 times of nickel), on the other hand, due to the affinity of carbon and chromium is very large, complex carbide form – with chromium series. So, from both a strength and corrosion performance of candle, the role of carbon in stainless steel flange is contradictory.
Understanding the influence of the rule, we can from the use of different requirements, choose different carbon content of stainless steel flange.
In terms of the five steel grade because the carbon content, strength and corrosion resistance are also differentiated, cr13 0 ~ 2 crl3 steel has good corrosion resistance strength less than 3 crl3 and 4 cr13 steel, used in the manufacture of structural parts, after two steel grade due to high carbon and high strength can be obtained much used in the manufacture of spring, knives and other required high strength and abrasion resistance parts. And as 18-8 cr-ni in order to overcome the intergranular corrosion of the stainless steel flange, the carbon content of steel can be below 0.03%, or join a greater affinity than chromium and carbon element (titanium or niobium), make it not chromium carbide formation, such as high hardness and wear resistance becomes main requirements, we can increase the carbon content of steel properly increase the chromium content at the same time, both to meet the requirements of the hardness and wear resistance, and both – corrosion function, industry is used as the bearing, measuring tool and cutting tool has a stainless steel flange 9 cr18 and 9 cr17movco steel, carbon content is up to 0.85 ~ 0.95%, because of their chromium content is correspondingly improved, so still meet the requirements of the corrosion resistance.
3, the role of nickel in stainless steel flange after cooperate with chromium to play out
Nickel is excellent corrosion resistant materials, as well as the importance of alloy steel alloying elements. Nickel is the formation of austenite in the steel element, but the low-carbon nickel steel to obtain pure austenitic organization, nickel content reaches 24%; And only make 27% nickel steel in some medium corrosion resistance change significantly. So the nickel can’t constitute stainless steel flange. But the nickel and chromium is present in the stainless steel flange at the same time, the nickel stainless steel flange has many valuable properties.
4, manganese and nitrogen can substitute for nickel chromium nickel stainless steel flange
Cr-ni austenitic steel advantage although a lot of, but in recent decades because of nickel-base heat resistant alloy and nickel of less than 20% of the heat intensity development and application of steel, and the growing development of chemical industry of growing demand for stainless steel flange, and nickel deposits are less and concentrated distribution in minority areas, therefore appeared worldwide nickel in terms of supply and demand contradiction. In stainless steel flange and so many other alloys, such as large castings and forgings with steel, tool steel, refractory steel, etc.), especially the relative lack of resources of the country of nickel, nickel widely carried out section and other elements for scientific research and production practice of nickel in this aspect research and application more on manganese and nitrogen instead of nickel in the stainless steel flange and heat resistant steel.
5 add titanium, stainless steel flange or niobium is to prevent intergranular corrosion.
6, molybdenum and copper can improve the corrosion resistance of stainless steel flange.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)