Type 317LMN
UNS S31726
A low-carbon, higher molybdenum austenitic stainless steel
frequently used for flue gas desulfurization service.
Description
Type 317LMN is a higher molybdenum austenitic
stainless steel further alloyed with nitrogen to provide
improved corrosion resistance relative to 316L and
317L, especially in acidic chloride-containing
environments. As a low carbon grade, 317LMN
may be welded without sensitization to intergranular
corrosion resulting from chromium carbide
precipitation on the grain boundaries.
Type 317LMN is non-magnetic in the
annealed condition.
Dual Certification
wide range of chemical processing applications
requiring a stainless steel with corrosion resistance
better than that of 316L and 317L.
Mechanical Properties at
Room Temperature
Table 1
Typical*
ASTM
Ultimate Tensile Strength, ksi
99
80 min
0.2% Offset Yield Strength, ksi
48
35 min
Elongation in 2 inches, %
52
40 min
Reduction in Area, %
61
Hardness, Rockwell B
85
96 max
*0.375 inch plate
When the chromium content of Type 317LMN
(S31726) is equal to or greater than 18.0%, it is
possible to certify the steel also as 317LM (S31725).
317LMN is stronger than 317LM and more corrosion
resistant, so this substitution is conservative. The
ASTM specification was changed for 317LM to
permit greater flexibility to the end user who seeks to
obtain small quantities of 317LM. The producer of
the steel must certify the material as S31725 if it is
to be used as S31725 instead of S31726.
Product Forms Available
Chemical Composition, wt. pct.
317LMN
Carbon
0.030 max
Manganese
2.00 max
Phosphorus
0.045 max
Sulfur
0.030 max
Silicon
0.75 max
Chromium
17.0-20.0
Nickel
13.5-17.5
Molybdenum
Plate
Sheet
Tubular Products
Welding Consumables
Table 2
Nitrogen*
4.0-5.0
0.10-0.20
*flat-rolled products only
Physical Properties
Table 3
Corrosion Resistance
Density, lb/in3
0.285
The combination of high molybdenum and nitrogen
gives Type 317LMN excellent resistance to chloride
pitting and crevice corrosion. It has been applied
for many years in the bodies, structural members,
and internals for scrubbers for flue gas desulfurization.
It is also a versatile and cost effective material in a
Modulus of Elasticity, psi
29 x 106
Coefficient of Thermal Expansion, 68-212F, /F
8.9 x 10-6
Thermal Conductivity, Btu/ft hrF
8.7
Heat Capacity, Btu/lbF
0.12
Electrical Resistivity, -inch
33.5 x 10-6
Outokumpu Stainless
Type 317LMN
Specifications
typically applied to the common austenitic
stainless steels. It can be used in heading, drawing,
bending, and upsetting. Because of its nitrogen
content, 317LMN will be slightly stronger and
work harden slightly faster than 316L.
Type 317LMN can be supplied to ASTM and
ASME specifications.
Heat Treatment
Type 317LMN is solution annealed by heating to
1900F minimum and followed by water quenching
or rapidly cooling by other means. 317LMN should
not be "stress relieved" by heat treatment other than
a full solution anneal. 317LMN cannot be hardened
by heat treatment.
Hot Working
Type 317LMN can be hot formed in the
1700-2200F range. For maximum corrosion
resistance, parts that have been hot formed should
be subsequently annealed at 1900F minimum and
water quenched or rapidly cooled by other means.
Workability
Cold Working
Welding
Type 317LMN is readily formed and fabricated
through the full range of cold working operations
Type 317LMN is readily welded by a full range of
conventional welding procedures (except oxyacetylene).
To produce a fusion zone with corrosion resistance
Lowest Temperature (F) at Which the Corrosion Rate Exceeds 5 mpy
654
SMO
Corrosion Environment
0.2% Hydrochloric Acid
>Boiling
1% Hydrochloric Acid
203
10% Sulfuric Acid
158
60% Sulfuric Acid
104
96% Sulfuric Acid
86
85% Phosphoric Acid
194
>Boiling
10% Nitric Acid
65% Nitric Acid
221
80% Acetic Acid
>Boiling
50% Formic Acid
158
50% Sodium Hydroxide
275
83% Phosphoric Acid + 2% Hydrofluoric Acid
185
>140
60% Nitric Acid + 2% Hydrochloric Acid
50% Acetic Acid + 50% Acetic Anhydride
>Boiling
1% Hydrochloric Acid + 0.3% Ferric Chloride >Boiling, p
10% Sulfuric Acid + 2000ppm Cl- + N2
149
10% Sulfuric Acid + 2000ppm Cl + SO2
167
WPA1, High Cl- Content
203
WPA2, High F- Content
176
ps = pitting can occur
ps = pitting/crevice corrosion can occur
254
SMO
>Boiling
158
140
104
68
230
>Boiling
212
>Boiling
212
239
194
140
>Boiling
203ps
104
140
176
140
904L
Type 316L Type
(2.7 Mo) 304
Table 4
2205 Code
Plus Two 2304
2507
>Boiling >Boiling >Boiling
122
86
86p
140
122
185
<54
95
113
248
203
176
>Boiling >Boiling >Boiling
212
212
212
>Boiling >Boiling
212p
212p
104
50
Boiling
194
185
248
149
113
>140
>140
>140
>Boiling
248
>Boiling
140ps
77p
68p
77
131
122
<<59p
122
50
<<50
95
50
<<50
>Boiling
>Boiling
167
<57
86
203
>Boiling
230
>Boiling
194
230
140
>140
230
203ps
122
104
203
167
>Boiling
185
140
<59
77
194
>Boiling
221
>Boiling
194
194
122
>140
212
113ps
95
<59
113
140
>Boiling
131
149
<<55
59
203
>Boiling
203
>Boiling
59
203
95
>140
194
68p
<55
<<50
86
95
WPA
P2O5
Cl-
F-
H 2SO4
Fe2O3
Al2O3
SiO2
CaO
MgO
1
2
54
54
0.20
0.02
0.50
2.0
4.0
4.0
0.30
0.30
0.20
0.20
0.10
0.10
0.20
0.20
0.70
0.70
Type 317LMN 3
similar to that of the base metal, filler metals of
Alloy 625 (AWS ERNiCrMo-3) or its lower
carbon version, ERNiCrMo-12, are commonly
used with 317LMN.
This table shows the lowest temperature at
which the corrosion rate exceeds 5 mpy.
All testing was done in accordance with the
requirements of the Materials Technology
Institute of the Chemical Process Industries (MTI).
Machinability
Type 317LMN is a very tough austenitic
stainless steel subject to work hardening
during deformation and resistant to chip breaking.
The higher molybdenum and the nitrogen
make the chip abrasive, increasing tool wear.
The best machining results are achieved with
slower speeds, heavier feeds, excellent lubrication,
sharp tooling, and powerful, rigid equipment.
Corrosion Performance of
Stainless Steels
The corrosion resistance of Type 317LMN is
only slightly below that of the 904L stainless
steel. Type 317LMN has a long service history
in flue gas scrubbing applications but has not
been fully evaluated for chemical applications.
However, it would be conservative to use
Table 4 as a guide, considering 317LMN to
be intermediate to 316L and 904L.
Technical Support
Outokumpu Stainless, Inc. assists users and
fabricators in the selection, qualification, installation,
operation, and maintenance of Type 317LMN
stainless steel. Technical personnel, supported
by the research laboratory of Outokumpu
Stainless, can draw on years of field experience
with Type 317LMN to help you make the
technically and economically correct
materials decision.
Outokumpu Stainless is prepared to discuss
individual applications and to provide data
and experience as a basis for selection and
application of Type 317LMN.
Outokumpu Stainless works closely with
its distributors to ensure timely availability of
Type 317LMN in the forms, sizes, and
quantities required by the user. For assistance
with technical questions and to obtain top quality
Type 317LMN, call Outokumpu Stainless, Inc.
at 1-800-833-8703.
Type 317LMN
1089EN, Schaumburg, USA. August 2004.
254 SMO and 654 SMO are trademarks of Outokumpu Stainless.
2205 Code Plus Two is a trademark of Outokumpu Stainless, Inc.
Information given in this brochure may be subject to alteration without notice. Care has been taken to ensure
that the contents of this publication are accurate, but Outokumpu Stainless and its subsidiary companies do not
accept responsibility for errors or for information which is found to be misleading. Suggestions for or descriptions
of the end use or application of products or methods of working are for information only and the company and
its subsidiaries accept no liability in respect thereof. Before using products supplied or manufactured by the company, customers should satisfy themselves of their suitability. If further assistance is required, the company, which
has extensive research facilities, will often be able to help.
Outokumpu Stainless is a core business
within Outokumpu, a dynamic metals
and technology group operating worldwide
and marketing its metals, metal products,
technology and services to customers in
a wide range of industries.
Outokumpu Stainless
Outokumpu Stainless, Inc., 425 North Martingale Road, Suite 1600, Schaumburg, IL 60173-2218 USA
Tel. 1-800-833-8703 Fax 1-800-545-8617 stainless.info@outokumpu.com
www.outokumpu.com/stainless/NA
