Difference Between Duplex and Inconel

Inconel® is a material that is specifically optimized for some of the toughest use conditions to be found in manufacturing while Duplex stainless steel is the most recent family of stainless steels. They are called duplex (or austenitic-ferritic) grades because their metallurgical structure consists of two phases, austenite (face-centered cubic lattice) and ferrite (body centered cubic lattice) in roughly equal proportions.

Duplex

Duplex and Super Duplex Steel Equivalent Grades

STANDARD	WERKSTOFF NR.	UNS
Duplex 1803	1.4462	S318032
Duplex 2205	1.4462	S32205
Super Duplex S2507	1.4410	S32750 / S32760 / S32950

Duplex and Super Duplex Composition

Trade Name	UNS	Super Duplex Industry Specifications	Chemical Composition	Min.Tensile (KSI)	Min.Yield (KSI)	Elongation %
SAF 2507®	UNS S32750	ASTM A182 F53, A240, A276, A479, A789, A790, A815, A928, A988 SAE J405	C 0.030 max Cr 24.0-26.0 Cu 0.5 max Mn 1.20 max Mo 3.0-5.0 N 0.24-0.32 Ni 6.0-8.0 P 0.035 max S 0.020 max Si 0.8 max	116	80	15
	UNS S32760	ASTM A182 F55, A240, A276, A314, A473, A479, A789, A790, A815, A928, A988 SAE J405	C 0.03 max Cr 24.0-26.0 Cu 0.5-1.0 Mn 1.0 max Mo 3.0-4.0 N 0.2-0.3 Ni 6.0-8.0 P 0.03 max S 0.01 max Si 1.0 max W 0.5-1.0	109	80	25
SAF 2205® 22Cr	UNS S31803	ASME SA-182 (F51), SA-240, SA-798, SA-790, SA-815 ASTM A182 (F51),A240, A276, A479, A789, A790, A815, A928, A988 SAE J405	C 0.30 max Cr 21.0-23.0 Mn 2.00 max Mo 2.50-3.50 N 0.08-0.20 Ni 4.50-6.50 P 0.030 max S 0.020 max Si 1.00 max	90	65	25
SAF 2205® 22Cr	UNS S32205	ASME SA-182 (F60), SA-240, SA-798, SA-790, SA-815 ASTM A182 (F60), A240, A276, A479, A480, A798, A790, A815, A928, A988 SAE J405	C 0.30 max Cr 22.0-23.0 Mn 2.00 max Mo 3.00-3.50 N 0.14-0.20 Ni 4.50-6.50 P 0.030 max S 0.020 max Si1.00 max	95	65	25

SAF 2205® & SAF 2507® are registered trademark for Sandvik

Inconel

Inconel Composition

Inconel	Element (% by mass)
Inconel	Ni	Cr	Fe	Mo	Nb	Co	Mn	Cu	Al	Ti	Si	C	S	P	B
600	72.0	14.0–17.0	6.0–10.0				1.0	0.5			0.5	0.15	0.015
617	44.2–56.0	20.0–24.0	3.0	8.0–10.0		10.0–15.0	0.5	0.5	0.8–1.5	0.6	0.5	0.15	0.015	0.015	0.006
625	58.0	20.0–23.0	5.0	8.0–10.0	3.15–4.15	1.0	0.5		0.4	0.4	0.5	0.1	0.015	0.015
690	59.5	30	9.2				0.35	0.01	0.02		0.35	0.019	0.003
718	50.0–55.0	17.0–21.0	balance	2.8–3.3	4.75–5.5	1.0	0.35	0.2–0.8	0.65–1.15	0.3	0.35	0.08	0.015	0.015	0.006
X-750	70.0	14.0–17.0	5.0–9.0		0.7–1.2	1.0	1.0	0.5	0.4–1.0	2.25–2.75	0.5	0.08	0.01

Inconel alloys

Alloys of inconel include:

Inconel 600: Solid solution strengthened
Inconel 601
Inconel 625: Acid resistant, good weldability. The LCF version is typically used in bellows.
Inconel 690: Low cobalt content for nuclear applications, and low resistivity
Inconel 713C: Precipitation hardenable nickel-chromium base cast alloy
Inconel 718: Gamma double prime strengthened with good weldability
Inconel 751: Increased aluminium content for improved rupture strength in the 1600 °F range
Inconel 792: Increased aluminium content for improved high temperature corrosion properties, used especially in gas turbines
Inconel 939: Gamma prime strengthened to increase weldability

Inconel Equivalent Grades

STANDARD	WERKSTOFF NR.	UNS	GOST	AFNOR	JIS	BS	EN	OR
Inconel 600	2.4816	N06600	МНЖМц 28-2,5-1,5	NC15FE11M	NCF 600	NA 13	NiCr15Fe	ЭИ868
Inconel 601	2.4851	N06601	XH60BT	NC23FeA	NCF 601	NA 49	NiCr23Fe	ЭИ868
Inconel 617	2.4663	N06617
Inconel 625	2.4856	N06625	ХН75МБТЮ	NC22DNB4M	NCF 625	NA 21	NiCr22Mo9Nb	ЭИ602
Inconel 690	2.4642	N06690
Inconel 718	2.4668	N07718
Inconel 725	-	N07725
Inconel X-750	2.4669	N07750

Inconel Melting Point, Density and Tensile Strength

	Density	Melting Point	Tensile Strength	Yield Strength (0.2%Offset)	Elongation
600	8.47 g/cm3	1413 °C (2580 °F)	Psi – 95,000 , MPa – 655	Psi – 45,000 , MPa – 310	40 %
601	8.1 g/cm3	1411 °C (2571 °F)	Psi – 80,000 , MPa – 550	Psi – 30,000 , MPa – 205	30 %
617	8.3g/cm³	1363°C	≥ 485 MPa	≥ 275 MPa	25 %
625	8.4 g/cm3	1350 °C (2460 °F)	Psi – 135,000 , MPa – 930	Psi – 75,000 , MPa – 517	42.5 %
690	8.3g/cm³	1363°C	≥ 485 MPa	≥ 275 MPa	25 %
718	8.2 g/cm3	1350 °C (2460 °F)	Psi – 135,000 , MPa – 930	Psi – 70,000 , MPa – 482	45 %
725	8.31 g/cm3	1271°C-1343 °C	1137 MPa	827 MPa	20 %
X-750	8.28 g/cm3	1430°C	1267 MPa	868 MPa	25 %