How the Austenite Ferrite Balance Achieved By yaang.com

DataTime:[2015-4-14]

To understand how duplex stainless steel works, first compare the composition of two familiar steel austenitic 304 (1.4301) and ferritic 430 (1.4016).

Structure	Grade	EN Number	C	Si	Mn	P	S	N	Cr	Ni	Mo
Ferritic	430	1.4016	0.08	1.00	1.00	0.040	0.015	-	16.0/18.0	-	-
Austenitic	304	1.4301	0.07	1.00	2.00	0.045	0.015	0.11	17.5/19.5	8.0/10.5	-

The important elements in stainless steel can be classified into ferritisers and austenitisers. Each element favours one structure or the other:
Ferritisers – Cr (chromium), Si (silicon), Mo (molybdenum), W (tungsten), Ti (titanium), Nb (niobium)
Austenitisers – C (carbon), Ni (nickel), Mn (manganese), N (nitrogen), Cu (copper)
Grade stainless steel 430 has a predominance of ferritisers and so is ferritic in structure. Grade stainless steel 304 becomes austenitic mainly through the use of about 8% nickel. To arrive at a duplex structure with about 50% of each phase, there has to be a balance between the austenitisers and the ferritisers. This explains why the nickel content of duplex stainless steels is generally lower than for austenitics.

Here are some typical compositions of duplex stainless steel:

Grade	EN No/UNS	Type	Approx Composition
			Cr	Ni	Mo	N	Mn	W	Cu
LDX2101	1.4162/ S32101	Lean	21.5	1.5	0.3	0.22	5	-	-
DX2202	1.4062/ S32202	Lean	23	2.5	0.3	0.2	-	-	-
RDN 903	1.4482/ S32001	Lean	20	1.8	0.2	0.11	4.2	-	-
2304	1.4362/ S32304	Lean	23	4.8	0.3	0.10	-	-	-
2205	1.4462/ S31803/ S32205	Standard	22	5.7	3.1	0.17	-	-	-
2507	1.4410/ S32750	Super	25	7	4	0.27	-	-	-
Zeron 100	1.4501/ S32760	Super	25	7	3.2	0.25	-	0.7	0.7
Ferrinox 255/ Uranus 2507Cu	1.4507/ S32520/ S32550	Super	25	6.5	3.5	0.25	-	-	1.5

In some of the recently developed stainless steel grades, nitrogen and manganese are used together to bring the nickel content to very low levels. This has a beneficial effect on price stability.
At present, we are still very much in the development phase of duplex stainless steel. Therefore, each mill is promoting its own particular brand. It is generally agreed that there are too many grades. However, this is likely to continue until the “winners” emerge.

Established in 2008, Yaang Pipe Industry Co., Limited is a professional organizer and one-stop-shop supplier for steel piping system products, including duplex stainless steel pipes and duplex stainless steel tubes, duplex stainless steel flangesand duplex stainless steel fittings, duplex stainless steel butt-welding pipe fittings, duplex stainless steel elbows, duplex stainless steel tees, duplex stainless steel reducers, duplex stainless steel stub end, duplex stainless steel gaskets, duplex stainless steel fasteners, duplex stainless steel valves, duplex stainless steel Sanitary Services etc. in China. We have devoted to providing the best solutions of steel materials and industrial equipment for our respected customers.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

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