300%20Series%20Stainless%20Steels

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• 300 Series Stainless Steels
• A look at the grades, properties and applications

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300 Series Stainless Steel Welding Consumables

• Austenitic Stainless Steels
• Iron Base (Fe) Typically low Carbon (C)
• Chromium (Cr) 15-30
• Nickel (Ni) 8-35
• Molybdenum (Mo) 0-5
• Mn, Si, Cu, Nb

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Stainless Steel Welding Alloys
The Austenitic Grades

• 308L
• 308H
• 308L(Si)
• 347
• 309L
• 309L(Si) 309LMo
• 316L

316L(Si)317L 312 310 320LR 330 385 307
Non-magnetic May contain an important magnetic
phase called ferrite
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Austenitic Stainless Steels
Ferrite

• A magnetic phase
• Can be estimated by
• Calculation diagrams
• or
• Measured

Ferrite
It is not a chemical element!
About 10FN
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Austenitic Stainless Steels

• Ferrite

• Calculated using diagrams based upon chemical
  element percentages.
• WRC 92 (Welding Research Council, 1992)
• Cr eq Cr Mo .7Nb
• Ferrite formers
• Ni eq Ni 35C 20N .25Cu
• Austenite formers
• Delong Diagram (introduced Nitrogen 308/316)
• Schaeffler Diagram

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Calculated by WRC 92
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Ferrite Number Measured on Actual Metal Specimen

• Fischer Feritscope

• MAGNE-GAGE

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Ferrite in 300 Series Stainless
Ferrite the up side
B.2 Effects of Ferrite The most important effect
of ferrite in nominally austenitic stainless
steel weldments is the well-established
relationship between a reduced sensitivity to hot
cracking and the presence of ferrite. The minimum
ferrite limit necessary to assure freedom from
cracking depends, among other factors, on the
weld metal composition. The upper limit results
from possible impairment of either mechanical or
corrosion properties, or both. The required
amount of ferrite can be ascertained by adjusting
the ration of ferrite formers (such as chromium)
to austenite promoters (such as nickel) within
limits allowed by the applicable specification.
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Ferrite in 300 Series Stainless
Ferrite the down side

• Intermetallic phases

• In High Temperature Applications, such as in
  refineries, gt800F Ferrite can transform to a
  brittle intermetallic phase Sigma. The result
  is a lack of ductility.
• In Low Temperature Applications -320F Ferrite
  can harm toughness
• Controlled ferrite content is the key!

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300 Series Stainless Groups

• Basic Cr Ni
• Cr Ni Mo
• Dissimilar Metal Joining
• Fully Austenitic

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Basic Cr Ni

• 18-8 Stainless 302/304 base metal
• 308 Family 19.5-22.0 Cr, 9.0-11.0 Ni
• 308L less Carbon .03 max
• 308H more Carbon .04-.08
• 308LSI more Silicon .65-1.00
• 347 Nb 10xC min to 1.0 max

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Basic Cr Ni Applications

• 308L 304 joining GTAW, SAW, FCAW process
• 308H High Temp apps hc Castings / Refineries
• 308LSI GMAW higher speed 304 joining
• 347 High Temp, minimize CrC precip
• 308LCF Low Temp Cryo, LNG

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Cr Ni Mo

• 16-18Cr, 10-14Ni, 2-3Mo UNS S31630
• Improved corrosion resistance chlorides /
  pitting
• 308 Family 19.5-22.0 Cr, 9.0-11.0 Ni
• 316 Family 18.0-20.0 Cr, 11.0-14.0Ni,2.0-3.0Mo
• 316L less Carbon .03 max
• 316LSI more Silicon .65-1.00
• 317L Ni (13.0-15.0), Mo (3.0-4.0)

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Basic Cr Ni Mo Applications

• Food processing, salt water
• 316L 316 joining GTAW, SAW, FCAW process
• 316LSI GMAW higher speed 316 joining
• 316LCF Low Temp Cryo, LNG coastal areas, ocean
  transport
• 317L Upgrade to 316L for additional corrosion
  protection

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Dissimilar Metal Joining

• Carbon Steel to Stainless - Dilution
• 308 Family 19.5-22.0 Cr, 9.0-11.0 Ni
• 316 Family 18.0-20.0 Cr, 11.0-14.0Ni, 2.0-3.0Mo
• 309L Types 308 Cr Ni
• 23.0-25.0Cr, 12.0-14.0 Ni
• 312 308 Cr
• 28.0-32.0Cr, 8.0-10.5 Ni
• 18 8 Mn (307) 5.0-8.0Mn, 17-20Cr, 7-10Ni
• 23 12 2 L (309LMo) 309L plus 2.0-3.5 Mo

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Dissimilar Metal Joining
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Dissimilar Metal Joining
CenterlineHot Crack

• Minimize dilution of carbon steel to prevent
  centerline cracking (lack of ferrite)
• In cases of high dilution, 312 may be the best
  choice
• PWHT / Stress Relief can make high ferrite welds
  brittle might be a factor

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Alert

• Not all AWS ER309LSi wires are the same.
• For Hot Mills / Rolling HRAP rod with high
  ferrite content is difficult. Higher scrap,
  higher cost..
• Premium brands like Lincoln Bluemax 309LSi have
  higher min FN levels
• Bluemax may work where other 309LSi brands will
  not.

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Fully Austenitic

• Specialty Grades
• 310 27Cr 21 Ni
• 330 16Cr 35Ni
• 320LR 20Cr 34Ni 2.5Mo 3.4Cu
• 385 21Cr 25Ni 4.6Mo 1.6Cu

• Applications
• High heat
• Severe corrosion
• Heat treat furnace components, baskets
• Chemical containment tanks

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Welding Fully Austenitic Stainless Steels

• 310, 320, 330, 385
• No Ferrite
• Susceptible to hot cracking Centerline cracking

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Reminder!
Ferrite the up side
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Fully Austenitic
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Welding Fully Austenitic Stainless Steels

• 310, 320, 330, 385
• No Ferrite

• 320LR Low Residual reduces crack sensitivity
  (less C, Si, P, S)
• No preheat
• Maximum interpass temperature of 212F (100C)
• Low heat input
• No weaving
• Small weld puddle
• Make an ugly weld with more reinforcement,
  convex fillet not concave fillet
• Electrodes with -15 or -16 coatings, not -17

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Summary

• 300 Series Stainless
• Understanding starts with 18-8 and add on
• Understand ferrite is important
• Understand properties and applications change
  with sometimes small adjustments to composition