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Stainless Steel Technical Guide
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Stainless Steel Technical Guide
Effects of Alloying Elements and Impurities in Stainless Steels and High Strength Heat-Resisting Alloys
Aluminum (AI)
- A strong ferrite former. Added to type 405 12% straight chrome weld metal to make it non-hardening (ferritic)
- Used to improve high temperature scaling resistance
- Added with titanium to some high strength alloys for age hardening effects
- Strong nitride former
Carbon (C)
- A strong austenite former
- Added to some high strength alloys for hardening and strengthening effects
- Adversely affects weld metal corrosion resistance and toughness at low temperatures
Columbium (Niobium) Cb(Nb)
- A strong carbide former. Used to stabilize austenitic stainless steels against precipitation of chromium carbides in the range of 800- 1600°F
- Moderate ferrite former
- Added to some high strength alloys for hardening and strengthening effects
- Added to some martensitic straight chromium stainless steels to tie up the carbon and reduce the hardening tendency of the steels
Cobolt (Co)
- Added to various alloys to impart strength and creep resistance at high temperatures
Chromium (Cr)
- A ferrite and carbide former
- Primary contributor to scaling and corrosion resistance
- In the stainless steels, this element has little or no effect on high temperature strength and creep strength
Copper (Cu)
- Used to improve corrosion resistance of stainless steel in many liquids which are reducing rather than oxidizing
Molybdenum (Mo)
- A ferrite and carbide former
- Used to improve high temperature strength and creep resistance
- Used to improve general corrosion resistance of steels in non-oxidizing media, and the resistance to pitting corrosion in all media
Manganese (Mn)
- Austenite former
- Improves weld metal crack resistance in fully austenitic alloys
Nitrogen (N)
- A strong austenite former
- Used to minimize grain grown in high chromium straight chromium steels at high temperatures
- Adversely affects weld metal toughness at cryogenic temperatures
- Raises strength
Nickel (Ni)
- An austenite former
- Used to improve the general corrosion resistance against non-oxidizing liquids
- Sometimes added in small amounts to straight chromium grades to improve the mechanical properties
- Generally improves weld metal toughness
Phosphorus (P) Sulphur (S) Selenium (Se)
- One of these three elements is occasionally added to stainless steels in conjunction with a small amount of Molybdenum or Zirconium to improve machinability of the steel
- All three promote cracking in weld metal
Silicon (Si)
- A ferrite former
- Used to increase the corrosion resistance of austenitic steels
- Used to improve high temperature scaling resistance
- Used to improve resistance of high temperature steels to carburization
Titanium (Ti)
- A strong carbide and nitride former. Used to stabilize austenitic stainless steels against precipitation of chromium carbides in the range of 800-1600°F
- A strong ferrite former
- Added to some high strength heat resisting alloys for its hardening and strengthening effects
- Added with aluminum to some high strength heat resisting alloys for age hardening effects
Tungsten (W)
- Improves the high temperature strength and creep resistance of some high temperature alloys
- A strong ferrite former
- Stainless Steel Covered Electrodes
- Electrode Identification
- Commercial stainless electrodes are imprinted with the AWS grade and, frequently, a lot number