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

1. 300 Series Stainless Steels A look at the grades, properties and applications

2. 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

3. 308L 308H 308L(Si) 347 309L 309L(Si) 309LMo 316L Stainless Steel Welding Alloys The Austenitic Grades: 316L(Si)317L 312 310 320LR 330 385 307 Non-magnetic May contain an important magnetic phase called ferrite

4. A magnetic phase Can be estimated by Calculation diagrams or Measured Austenitic Stainless Steels Ferrite Ferrite It is not a chemical element! About 10FN

5. Ferrite Austenitic Stainless Steels • 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

6. Calculated by WRC 92

7. Ferrite Number Measured on Actual Metal Specimen Fischer Feritscope MAGNE-GAGE

8. 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.

9. Ferrite in 300 Series Stainless Ferrite – the down side • In High Temperature Applications, such as in refineries, >800F – 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! Intermetallic phases

10. 300 Series Stainless “Groups” • Basic Cr Ni • Cr Ni Mo • Dissimilar Metal Joining • Fully Austenitic

11. 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

12. 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 • 308L”CF” Low Temp –Cryo, LNG

13. Cr Ni Mo 16-18%Cr, 10-14%Ni, 2-3%Mo 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, 11.0-14.0%Ni,2.0-3.0%Mo • 316L less Carbon .03% max • 316LSI more Silicon .65-1.00% • 317L +Ni (13.0-15.0), +Mo (3.0-4.0)

14. Basic Cr Ni Mo Applications Food processing, salt water • 316L 316 joining GTAW, SAW, FCAW process • 316LSI GMAW higher speed 316 joining • 316L”CF” Low Temp –Cryo, LNG coastal areas, ocean transport • 317L Upgrade to 316L for additional corrosion protection

15. 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 23.0-25.0%Cr, 12.0-14.0% Ni • 312 308 ++ Cr 28.0-32.0%Cr, 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

16. Dissimilar Metal Joining

17. 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

18. 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.

19. Fully Austenitic Applications • High heat • Severe corrosion • Heat treat furnace components, baskets • Chemical containment tanks Specialty Grades • 310 27%Cr 21% Ni • 330 16%Cr 35%Ni • 320LR 20%Cr 34%Ni 2.5%Mo 3.4%Cu • 385 21%Cr 25%Ni 4.6%Mo 1.6%Cu

20. 310, 320, 330, 385 No Ferrite Susceptible to hot cracking – Centerline cracking Welding Fully Austenitic Stainless Steels

21. Reminder! Ferrite – the up side

22. Fully Austenitic

23. 310, 320, 330, 385 No Ferrite Welding Fully Austenitic Stainless Steels • 320LR “Low Residual” reduces crack sensitivity (less C, Si, P, S) • No preheat • Maximum interpass temperature of 212°F (100°C) • 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

24. 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