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317LMN Stainless Steel

Penn Stainless inventory now includes Alloy 317LMN (UNS S31726) in plate and processed flat bar.

Overview

General Properties

Alloy 317LMN is an austenitic, higher-molybdenum bearing stainless steel further alloyed with nitrogen that is particularly effective in enhancing resistance to pitting and crevice corrosion and also has excellent resistance to chemical attack. Its low carbon composition provides resistance to sensitization during welding and the additional nitrogen serves to increase its strength. Alloy 317LMN has the highest aqueous corrosion resistance of all standard stainless steels and also has higher creep, stress-to-rupture, and tensile strength at higher temperatures.

Specifications: UNS S31726

Applications:

Similar to alloy 317L, 317LMN is commonly used to handle sulfur, pulp liquor, acid dyestuffs, bleaching solutions, flue gasses, and many chemical compounds. Industries that frequently use alloy Alloy 317LMN include:

  • Paper and pulp
  • Textile
  • Food processing
  • Process equipment

 Standards:

  • ASTM/ASME: UNS S31726
  • EURONORM:  FeMi35Cr20Cu4Mo2
  • DIN: 1.4439
Resistance

Corrosion Resistance:

  • Alloy 317LMN, along with 317L, is considered more resistant to atmospheric and other mild type of corrosion, along with solutions of sulfuric acids, than conventional chromium-nickel stainless steels
  • Resistant to sulfuric acid concentrations at temperatures as high as 129oF (49oC)
  • High molybdenum and nickel content significantly improves chloride pitting and crevice corrosion
  • Low carbon content provides sensitization to intergranualr corrosion during welding and other thermal processes
  • Has the highest aqueous corrosion resistance of all standard stainless steels

Oxidation Resistance:

  • All chromium-nickel-molybdenum stainless steels have excellent resistance to oxidation
  • Has a low rate of scaling in ordinary atmospheres at temperatures up to 1600 to 1650oF (871 to 899oC)
Processing

Heat Treatment:

  • All common hot working processes are possible with this alloy
  • Heat to 2100 to 230°F (1149 to 1260°C)
  • Avoid working below 1700°F
  • Should not be “stress relieved” by any heat treatment other than a full solution anneal
  • Cannot be hardened by heat treatment

Welding Characteristics:

  • Weldable by all common methods
  • Because of the low carbon restriction, carbide precipitation along welded boundaries will be minimized
  • Use of an over-alloyed filler is suggested to maintain corrosion resistance in the as-welded condition

Machinability:

  • Substantially tougher than mild steel
  • Requires heavy feeds and slow speeds to overcome its tendency towards work hardening
Properties

Chemical Properties:

  C Mn Si Cr Ni Mo P S N Fe
317LMN 0.035 max 2.00 max 0.75 max min: 17.0 max: 20.0 min: 13.50 max: 17.50 min: 4.0 max: 5.0 0.04 max 0.03 max min: 0.10 max: 0.20 balance

Mechanical Properties:

Grade Tensile Strength ksi (MPa) min Yield Strength 0.2% offset ksi (MPa) min Elongation (% in 50mm) min Hardness (Brinell) MAX Hardness (Rockwell B) MAX
317LMN 80 (550) 35 (240) 40 223 96

Physical Properties:

Denstiy
lbm/in^3
Coefficient of
Thermal Expansion (min/in)-°F
Thermal Conductivity BTU/ft^2-hr-°F-in Specific Heat BTU/lbm -°F Modules of Elasticity (annealed)^2-psi
at 68 °F at 77 – 212°F at 77 – 1832°F 68-212°F at 32 – 212°F in tension (E)
0.29 9.2 10.8 100.8 0.11 28 x 10^6
317LMN