CB30 Stainless Steel Properties, Composition & Equivalent

CB30 ASTM A743          UNS:J91803        Alloy Family: Martensitic Stainless Steel       Equivalent: 431 Stainless Steel        

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What is CB30 Stainless Steel ?

CB30 is a ferritic stainless steel. It has high yield strength, low plasticity, high thermal conductivity, low expansion coefficient and excellent corrosion cracking resistance.

This alloy can obtain high mechanical properties by heat treatment, and its corrosion resistance is better than CA15 steel and 430 steel.

It is a kind of martensitic stainless steel with better strength and toughness. It has good corrosion resistance to oxidizing acids, most organic acids and organic salts. It is generally applicable to the production of nitric acid, acetic acid, light industry, textile and other industries, such as shafts, piston rods, pumps, etc., which require both strength and toughness and corrosion resistance.

CB30 ASTM A743

CB30 Chemical Composition

C Mn Si P S Cr Ni
Max 0.30 1.00 1.50 0.04 0.04 21.0 2.0
Min 18.0
CB30 Equivalent: 431 stainless steel

Heat treatment

(1) Heat to 1450°F [790°C] minimum, and air cool, or

(2) Heat to 1450°F [790°C] minimum, and furnace cool

(3) The ferritic stainless steel of this material is heated to 770-800 ℃, then kept for 0.5h, and cooled with coolant; 

Mechanical Properties

GradeASTM A743
Reduction of Area, min / %35 %
Yield Strength, minKsi – 30, MPa – 205
Tensile Strength, minKsi – 65, MPa – 450
Elongation[50mm], min / %12 %


  • High yield strength
  • Low plasticity
  • High thermal conductivity
  • Low coefficient of expansion
  • Excellent corrosion resistance
  • Excellent cracking resistance


  • Nitric acid industry parts
  • light industry
  • Textile Parts
  • Corrosion resistant bearing
  • Corrosion resistant pump

More about CB30 heat treatment

The cooled ferrite stainless steel CB30 material is heated to 600-650 ℃ for 30min for tempering treatment, and then cooled to normal temperature by air cooling after heat preservation, and the temperature cooling rate shall be greater than or equal to 200 ℃ / min. It is further characterized in that the coolant is quenching oil. After adopting the material and heat treatment process of the invention, the chemical composition of the material is optimized, the cost of the metal furnace charge is reduced, the mechanical properties of the parts are satisfied, the service life of the parts is improved, the internal stress of the structure is reduced by rapid cooling, the brittleness at 475 ℃ is avoided, the toughness of the material is improved, and the brittleness cracking of the thin-walled tubular parts processed in the subsequent process is reduced.

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