Mechanical Properties of UNS S39274 Superduplex Stainless Steel Work Hardened and Solution Annealed

Conceição, J.N.; Correa, E.O.; Gonzaga, A.C.; Pardal, J. M.; Tavares, S.S.M.

doi:10.1590/1980-5373-MR-2022-0108

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Articles • Mat. Res. 25 • 2022 • https://doi.org/10.1590/1980-5373-MR-2022-0108 copy

Mechanical Properties of UNS S39274 Superduplex Stainless Steel Work Hardened and Solution Annealed

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

UNS S39274 is a W-alloyed superduplex stainless steel used in critical services in the oil and gas production. This material was selected for tubullars used in oil country tubular goods, below the Christmas tree. In order to achieve high mechanical strength the seamless tubes are cold drawn in a costly operation. In this work the mechanical properties of a cold drawn seamless were characterized and compared to three solution treated materials. Tensile curves were obtained and modelled by Hollomon’s, Ludwik’s and Voce’s models, where the last one presented the higher correlation coefficients in all cases. The hardness and impact toughness at -46^oC were measured and discussed. The results were analyzed taking into aconunt the microstructural changes produced by cold drawning and annealing.

Keywords:
superduplex stainless steel; solution annealing; mechanical properties

C	Cr	Ni	Mo	W	Cu	S	P	N	Fe	PREN
0.028	24.790	6.600	3.220	1.750	0.510	0.002	0.017	0.255	Bal.	42.40

Specimen	Quantitative metallography		Simulation prediction (solution temperature)
Specimen		% austenite (γ)	% ferrite (δ)	% austenite (γ)	% ferrite (δ)	% sigma (σ)
AR-CW	56.1 ± 7.2	43.9 ± 7.2	-	-	-
ST-1050	60.8 ± 8.5	39.2 ± 8.5	56.4	41.9	1.7
ST-1100	52.4 ± 5.1	47.6 ± 5.1	50.9	49.1	0.0
ST-1150	51.3 ± 4.9	48.7 ± 4.9	45.6	54.4	0.0

T(^oC)	Phase	Cr	Ni	Mo	W	N	C	PREN_W
1050	Ferrite (δ)	26.638	4.682	3.903	2.143	0.0314	0.0079	43.56
1050	Austenite (γ)	23.202	8.133	2.460	1.314	0.4272	0.0476	40.32
1100	Ferrite (δ)	26.271	4.975	3.935	2.136	0.0416	0.0088	43.45
1100	Austenite (γ)	23.310	8.223	2.506	1.364	0.4641	0.0512	41.26
1150	Ferrite (δ)	25.936	5.250	3.828	2.058	0.0546	0.0099	42.84
1150	Austenite (γ)	23.369	8.274	2.467	1.369	0.4990	0.0549	41.75

Specimen	Vickers Hardness (HV10)	Microhardness (HV0.025)
Specimen	Vickers Hardness (HV10)			Ferrite (δ)	Austenite (γ)
AR-CW	(344 ± 7)	323 ± 20	331 ± 16
ST-1050	(281 ± 9)	317 ± 15	265 ± 11
ST-1100	(285 ± 5)	299 ± 16	257 ± 11
ST-1150	(279 ± 2)	273 ± 11	246 ± 10

Tensile Properties		Specimen
				AR-CW		ST-1050		ST-1100		ST-1150
				(A)	(B)	(A)	(B)	(A)	(B)	(A)	(B)
σ_YS (MPa)		947	974	628	641	609	652	632	646
σ_YS (MPa)		(960 ± 19)		(634 ± 9)		(630 ± 30)		(639 ± 10)
σ_UTS (MPa)		999	1014	842	841	831	841	824	833
σ_UTS (MPa)		(1007 ± 10)		(842 ± 0)		(836 ± 8)		(829 ± 6)
Elongation (%)	Plastic	19.1	16.2	35.7	36.5	35.4	28.8	28.6	35.2
	Plastic	(17.7 ± 2.1)		(36.1 ± 0.6)		(32.1 ± 4.7)		(31.9 ± 4.6)
	Uniform	5.3	4.1	26.31	28.04	27.4	21.3	21.9	27.6
	Uniform	(4.7 ± 0.9)		(27.2 ± 1.2)		(24.4 ± 4.3)		(24.7 ± 4.0)
Reduction of Area (%)		78.3	74.7	81.5	83.0	81.6	82.3	80.4	73.9
Reduction of Area (%)		(76.5 ± 2.6)		(82.2 ± 1.1)		(82.0 ± 0.5)		(77.2 ± 4.6)
σ x ε Area (10¹²J/m³)		178.2	151.3	279.5	287.8	272.4	225.0	221.0	276.9
σ x ε Area (10¹²J/m³)		(164.7 ± 19.0)		(283.7 ± 5.9)		(248.7 ± 33.5)		(249.0 ± 39.5)

Model		Specimen
				AR-CW		ST-1050		ST-1100		ST-1150
				(A)	(B)	(A)	(B)	(A)	(B)	(A)	(B)
Hollomon	K_H (MPa)	1202.7	1239.0	1222.0	1224.0	1225.0	1162.2	1151.6	1201.8
	K_H (MPa)	(1220.8 ± 25.7)		(1223.0 ± 1.4)		(1193.6 ± 44.4)		(1176.7 ± 35.5)
	n_H	0.042	0.043	0.130	0.129	0.139	0.107	0.113	0.124
	n_H	(0.042 ± 0.001)		(0.129 ± 0.001)		(0.123 ± 0.023)		(0.118 ± 0.007)
	R²	0.930	0.939	0.929	0.862	0.859	0.881	0.922	0.915
Ludwik	σ_o (MPa)	755	773	499	510	533	553	510	537
	σ_o (MPa)	(764 ± 13)		(505 ± 8)		(543 ± 14)		(524 ± 19)
	K_L (MPa)	546.4	617.5	944.8	944.6	1001.9	856.0	867.5	901.1
	K_L (MPa)	(582.0 ± 50.3)		(944.7 ± 0.1)		(929.0 ± 103.2)		(884.3 ± 23.8)
	n_L	0.184	0.203	0.376	0.388	0.470	0.384	0.365	0.406
	n_L	(0.194 ± 0.014)		(0.382 ± 0.009)		(0.427 ± 0.061)		(0.386 ± 0.029)
	R²	0.865	0.870	0.985	0.934	0.939	0.841	0.986	0.986
Voce	σ_o (MPa)	755	773	499	510	533	553	510	537
	σ_o (MPa)	(764 ± 13)		(505 ± 8)		(543 ± 14)		(524 ± 19)
	P1 (MPa)	1697.1	2313.7	1629.7	1581.9	1622.0	1661.8	1661.5	1495.2
	P1 (MPa)	(2005.4 ± 436.0)		(1605.8 ± 33.8)		(1641.9 ± 28.1)		(1578.4 ± 117.5)
	P2 (MPa)	226.3	219.1	212.8	205.4	159.7	174.5	192.4	184.4
	P2 (MPa)	(222.7 ± 5.1)		(209.1 ± 5.3)		(167.1 ± 10.5)		(188.4 ± 5.7)
	P3	1179.5	1455.2	375.4	425.4	226.7	336.5	412.4	323.5
	P3	(1317.3 ± 194.9)		(400.4 ± 35.3)		(281.6 ± 77.6)		(368.0 ± 62.8)
	R²	0.993	0.992	0.992	0.990	0.993	0.991	0.992	0.993

Specimen	Absorbed Energy (J)		Lateral Expansion (mm)		Shear Fracture (%)
Specimen		Tests	Avg	Tests	Avg	Tests	Avg
AR-CW (A)	172.0	(170.5 ± 2.1)	2.24	(2.21 ± 0.04)	75	(71.0 ± 5.7)
AR-CW (B)	169.0	(170.5 ± 2.1)	2.18	(2.21 ± 0.04)	67	(71.0 ± 5.7)
ST-1050 (A)	269.0	(265.5 ± 17.7)	2.51	(2.52 ± 0.01)	86	(84.5 ± 2.1)
ST-1050 (B)	244.0	(265.5 ± 17.7)	2.53	(2.52 ± 0.01)	83	(84.5 ± 2.1)
ST-1100 (A)	294.0	(294.0 ± 0.0)	2.59	(2.42 ± 0.25)	94	(94.5 ± 0.7)
ST-1100 (B)	294.0	(294.0 ± 0.0)	2.24	(2.42 ± 0.25)	95	(94.5 ± 0.7)
ST-1150 (A)	179.0	(165.5 ± 19.1)	2.20	(2.04 ± 0.23)	72	(69.0 ± 4.2)
ST-1150 (B)	152.0	(165.5 ± 19.1)	1.88	(2.04 ± 0.23)	66	(69.0 ± 4.2)

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