Metallurgical and Stress State Factors Which Affect the Creep and Fracture Behavior of 9% Cr Steels

Table 1

Comparison of recommended chemical composition ranges for Grade 91 steel products.

Element	SA-335 P91 [17]	ORNL 6303 spec. [18]	ORNL 6303 target [18]	1023199 [19]	P91 book [20]	V&M [21]	Arcelor Gr. 91 plate [22]	Arcelor Gr. 22 plate [23]	EPRI proposal for Grade 91 Cl. 2
C	0.08–0.12	0.08–0.12	0.1	0.08–0.12	0.08–0.12	0.08–0.12	—	—	0.08–0.12
Mn	0.30–0.60	0.30–0.50	0.4	0.30–0.60	0.30–0.50	0.30–0.50	—	—	0.30–0.50
P	0.020 max	0.020 max	<0.010	0.020 max	0.020 max	0.020 max	0.010 max	0.008	0.020 max
S	0.010 max	0.010 max	<0.010	0.010 max	0.005 max	0.005 max	0.005 max	0.005	0.005 max
Si	0.20–0.50	0.20–0.50	0.2	0.20–0.50	0.20–0.40	0.20–0.40	—	—	0.20–0.40
Cr	8.00–9.50	8.0–9.0	8.5	8.00–9.50	8.00–9.50	8.00–9.50	—	—	8.00–9.50
Mo	0.85–1.05	0.85–1.05	0.95	0.85–1.05	0.85–1.05	0.85–1.05	—	—	0.85–1.05
V	0.18–0.25	0.18–0.25	0.21	0.18–0.25	0.18–0.25	0.18–0.25	—	—	0.18–0.25
Nb	0.06–0.10	0.06–0.10	0.08	0.06–0.10	0.06–0.10	0.06–0.10	—	—	0.06–0.10
N	0.030–0.070	0.030–0.070	0.05	0.035–0.070	0.040–0.070	0.030–0.070	—	—	0.035–0.070
Ni	0.40 max	0.20 max	<0.10	0.20 max	0.40 max	0.20 max	—	—	0.20 max
Al	0.02 max	0.04 max	<0.02	0.020 max	0.025 max	0.025 max	—	—	0.015 max
Ti	0.01 max	0.01 max	<0.01	0.01 max	0.010 max	0.010 max	—	—	0.01 max
Zr	0.01 max	<0.01	<0.01	0.01 max	—	—	—	—	0.01 max
Cu	—	0.20 max	<0.10	0.25 max	0.10 max	0.10 max	—	—	0.10 max
As	—	—	—	0.012 max^1			—	0.01	0.010 max^1
Sn	—	—	—	0.010 max^1	0.020 max	0.020 max	—	0.01	0.010 max^1
Sb	—	<0.001	<0.001	0.003 max^1	0.010 max	0.010 max	—	0.0025	0.003 max^1
B	—	<0.001	<0.001	—	—	—	—	—	<0.001
W	—	<0.010	<0.010	—	—	—	—	—	<0.010
Pb	—	—	—	—	—	—	—	—	<0.001 max^1
N : Al ratio	—	—	—	4.0 min	—	—	—	—	4.0 min

¹The combined value of Sn + As + Sb + Pb < 0.010 weight percent.