317 Stainless Steel Plate Properties and Features

317 stainless steel plate is an austenitic alloy engineered for environments where standard grades simply fall short. Its elevated molybdenum and chromium content deliver superior resistance to pitting, crevice corrosion, and chloride attack - making it the material of choice for chemical processing, pulp and paper, and marine applications.

317 stainless steel is a high-performance austenitic alloy containing higher levels of chromium, nickel, and molybdenum than the more common 304 or 316 grades. The addition of at least 3% molybdenum - compared to 2% in grade 316 - is its defining characteristic, dramatically improving resistance to pitting and crevice corrosion in halide-bearing and acidic environments.

In plate form, 317 is widely used to fabricate pressure vessels, heat exchanger shells, scrubbers, digesters, and structural linings where long service life in aggressive media is a primary requirement. Its fully austenitic microstructure also makes it non-magnetic and readily weldable without post-weld heat treatment in most applications.

The chemical composition of 317 stainless steel plate conforms to ASTM A240. Key elements and their specified ranges are as follows:

Element	Specified Range	Role in Performance
Chromium (Cr)	18.0–20.0%	Passive film formation; general corrosion resistance
Nickel (Ni)	11.0–15.0%	Austenite stabilizer; toughness and ductility
Molybdenum (Mo)	3.0–4.0%	Pitting and crevice corrosion resistance
Carbon (C)	≤ 0.08%	Strength; controlled to reduce sensitization
Manganese (Mn)	≤ 2.00%	Austenite stability; deoxidation
Silicon (Si)	≤ 0.75%	Deoxidation; high-temperature oxidation resistance
Phosphorus (P)	≤ 0.045%	Controlled impurity
Sulfur (S)	≤ 0.030%	Controlled impurity
Iron (Fe)	Balance	Base metal

The 3–4% molybdenum content in grade 317 is meaningfully higher than the 2–3% found in grade 316. This difference directly translates into a higher Pitting Resistance Equivalent Number (PREN), providing measurably better protection against chloride-induced pitting - one of the most common failure modes in stainless steel equipment.

317 stainless steel plate in the annealed condition meets the following minimum mechanical requirements per ASTM A240:

Tensile Strength

≥ 515 MPa

(≥ 75 ksi)

Yield Strength (0.2%)

≥ 205 MPa

(≥ 30 ksi)

Elongation

≥ 40%

in 50 mm gauge

Hardness (Brinell)

≤ 217 HB

Rockwell ≤ 95 HRB

These values reflect the annealed (solution-treated) delivery condition. Like all austenitic stainless steels, grade 317 cannot be hardened by heat treatment - strength increases are achieved through cold working. The high elongation value (≥ 40%) confirms excellent ductility, which simplifies forming, bending, and press operations during fabrication.

Property	Value
Density	7.98 g/cm³ (0.288 lb/in³)
Melting Range	1375–1400 °C (2507–2552 °F)
Thermal Conductivity (at 100 °C)	~14.4 W/(m·K)
Coefficient of Thermal Expansion	16.5 µm/(m·°C) (20–100 °C)
Electrical Resistivity	~740 nΩ·m
Modulus of Elasticity	193 GPa (28,000 ksi)
Magnetic Permeability	Non-magnetic (µ ≈ 1.02)

Corrosion resistance is the defining advantage of 317 stainless steel plate, and it is directly tied to the alloy's elevated molybdenum content.

Pitting and Crevice Corrosion

Grade 317 achieves a Pitting Resistance Equivalent Number (PREN) of approximately 30–33, compared to around 25–27 for grade 316. A higher PREN means the material can withstand higher chloride concentrations and temperatures before pitting begins. This makes 317 plate well suited for equipment handling seawater, brines, bleaching compounds, and chloride-containing process streams.

Acidic and Reducing Environments

Molybdenum also improves resistance to reducing acids, particularly sulfuric acid at moderate concentrations and phosphoric acid. Grade 317 outperforms both 304 and 316 in these environments, offering longer service intervals and reduced maintenance frequency.

High-Temperature Oxidation

317 stainless steel maintains its protective oxide layer up to approximately 870 °C (1600 °F) in continuous service. For intermittent service, the practical upper limit is around 925 °C (1700 °F). Beyond these temperatures, sensitization or scaling may occur, and higher-alloy grades should be considered.

Engineers frequently face the choice between 317 and 316 plate. Both are excellent austenitic grades, but their performance envelopes differ in meaningful ways:

Grade 316

– 2–3% molybdenum

– PREN approx. 25–27

– Lower material cost

– Wider global availability

– Suitable for moderate chloride exposure

– Good general corrosion resistance

Grade 317

– 3–4% molybdenum

– PREN approx. 30–33

– Higher initial cost

– Superior in aggressive chloride service

– Better resistance to reducing acids

– Preferred for chemical and pulp/paper plant

When operating conditions involve hot chloride solutions, dilute sulfuric acid, or bleach-containing streams, the additional molybdenum in 317 typically justifies the premium - not just on performance grounds, but through reduced replacement and downtime costs over the equipment's service life.

317 stainless steel plate is readily fabricated using standard austenitic practices. Key guidelines include:

Welding is performed using matching filler metals such as ER317L (for MIG/TIG processes) or E317L electrodes. The low-carbon "L" filler variants are strongly recommended to minimize carbide precipitation in the heat-affected zone, preserving corrosion resistance near the weld seam. Post-weld annealing is not required for most plate thicknesses when L-grade fillers are used.

Cold forming operations - bending, rolling, press forming - are executed using the same equipment as for 316, though allowance should be made for grade 317's slightly higher work-hardening rate. Machining requires sharp tooling, moderate cutting speeds, and effective coolant to avoid work hardening the cut surface.

317 stainless steel plate is specified wherever a grade 316 plate would be marginal - particularly in environments combining chlorides, acids, and elevated temperatures. Representative applications include:

Chemical process vessels

Pulp and paper digesters

Flue gas desulfurization

Seawater heat exchangers

Bleach plant equipment

Pharmaceutical reactors

Offshore platform decking

Sulfuric acid handling

Dye and textile plant

Food processing equipment

Marine exhaust systems

Pressure vessel shells

317 stainless steel plate is produced in accordance with the following key standards. Always request certified mill test reports (MTRs) confirming compliance with the applicable specification:

Standard	Scope
ASTM A240	Chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels
ASTM A480	General requirements for flat-rolled stainless steel plate, sheet, and strip
ASME SA-240	ASME pressure vessel code equivalent of ASTM A240
EN 10028-7	European flat products for pressure purposes - stainless steels

Q: Is 317 stainless steel better than 316?

A: In environments with higher chloride concentrations, reducing acids, or more aggressive chemical media, yes - 317 outperforms 316 due to its higher molybdenum content. For standard applications with moderate corrosive exposure, 316 is often sufficient and more economical.

Q: What is 317L stainless steel?

A: 317L is the low-carbon version of grade 317, with carbon limited to 0.03% maximum. The lower carbon content significantly reduces the risk of sensitization (carbide precipitation at grain boundaries) during welding, preserving corrosion resistance in the heat-affected zone without requiring post-weld annealing.

Q: Is 317 stainless steel magnetic?

A: In the annealed condition, 317 stainless steel is essentially non-magnetic (magnetic permeability ≈ 1.02). Cold working can induce a small amount of deformation-induced martensite, making heavily worked areas slightly magnetic - but the material remains far less magnetic than ferritic or martensitic stainless grades.

Q: Can 317 stainless steel plate be used at high temperatures?

A: Grade 317 can be used in continuous service up to approximately 870 °C (1600 °F). For temperatures beyond this, the carbide precipitation range (around 425–870 °C) should be factored into design - using 317L or specifying solution annealing after fabrication mitigates sensitization risk in this range.

Disclaimer: Data presented in this document is based on standard composition and property ranges per ASTM A240 and industry reference sources. Actual properties may vary by heat, product form, and processing condition. All critical applications should reference current applicable standards and certified material test reports. This content is intended for general engineering guidance only.