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What are the different types of stainless steel?

Date:2022-10-17View:366Tags:Steel Pipe Flange,Rectangular Steel Tube,Square Steel Tube

Stainless steel is recognized for its strength, beauty, and resistance to corrosion. However, not all stainless steel is alike. The metal comes in five distinct families and about 150 different grades.


  • Austenitic stainless steel
  • Ferritic stainless steel
  • Martensitic stainless steel
  • Precipitation Hardened stainless steel
  • Duplex / Super Duplex stainless steel



Austenitic stainless steel

Austenitic stainless steel is non-magnetic in nature and has very high corrosion resistance.

Excellent weldability, formability, fabricability, and ductility.

High Corrosion resistance at temp up to 1500°F.

Use for both low and high-temperature service.

This type of steel is hardenable by cold working.

It has a Face centered Cubic –FCC (fine grain structure) structure.

Possess high impact strength at low temp.

These types of SS are widely used in the process industry and a variety of industrial applications; cookware is also manufactured from Austenitic stainless steel.

Type 304, 304L, 316, and 316L are some of the examples of Austenitic stainless steel. Refer to the chart given below.

Grade

Alloy Component

Characteristics & Application

303

18Cr-8Ni-S

Free cutting steel

304

18Cr-8Ni

Basic steel grade. Use for general purpose steel for many applications in many fields

304H

18Cr-8Ni-High C

304L

18Cr-8Ni-Low C

304N

18Cr-8Ni-N

High   strength

304LN

18Cr-8Ni-Low C-N

lntergranular corrosion resistance

309

22Cr-12Ni

Oxidation resistance. Use in Chemical plant pipes and tubes, Radiant tubes, Thermocouple protection tubes

309S

22Cr-12Ni

310

25Cr-20Ni

310S

25Cr-20Ni

312L

20Cr-18Ni-6Mo-0.2N

Seawater resistance. Use in Seawater desalination plant pipes

316

18Cr-12Ni-2Mo

Corrosion resistance. Use in LNG plant pipes, Boilers, nuclear power and chemical industry pipes and tubes

316H

18Cr-12Ni-2Mo-High C

316L

18Cr-12Ni-2Mo-Low C

316Ti

18Cr-12Ni-Mo-Ti

lntergranular corrosion resistance

317

18Cr-12Ni-3Mo

Pitting corrosion resistance. Use in Chemical tanker pipes

317L

18Cr-12Ni-3Mo-Low C

321

18Cr-9Ni-Ti

Intergranular corrosion resistance. Use in Chemical plant pipes

321H

18Cr-9Ni-Ti-High C

High-temperature strength. Use in Boiler heater tubes and reheater tubes

347

18Cr-9Ni-Nb

lntergranular corrosion resistance. Use in Chemical plant pipes and tubes

347H

18Cr-9Ni-Nb-Low C

High-temperature strength. Use in Boiler heater tubes and reheater tubes

310MoLN

25Cr-22Ni-2Mo-N

lntergranular corrosion resistance. Use in Urea reactor tubes

Ferritic stainless steel

Ferritic stainless steel is magnetic and contains high carbon; therefore, it is brittle and has relatively poor corrosion resistance as compared to austenitic SS.

Non-hardenable by heat treatment.

Body-centered cubic -BCC (coarse grain structure).

Ferritic stainless steel has a high resistance to chloride stress corrosion cracking, so it is used in marine, petrochemical, heat exchangers, and furnace application, where high chloride content is there.

Type 409, 430, 439, 444, and 446 are examples of Ferritic stainless steel. Refer to the chart given below.

Grade

Alloy Component

Characteristics & Application

430

18Cr

Chloride corrosion resistance and stress corrosion crack resistance. Use in water heater pipes

444

19Cr-2Mo-Ti/Nb

446

25Cr-N

Martensitic stainless steel

Martensitic stainless steel has high hardness and poor corrosion resistance than austenitic SS.

Heat treatable to high hardness level.

Crystallographic form-distorted structure.

It is used in the manufacturing of sports knives and multi-purpose tools.

Type 405, 410, and 420 are examples of Martensitic stainless steel. Refer to the chart given below.

Grade

Alloy Component

Characteristics & Application

405

13Cr-AI

Low thermal expansion. Use in automotive exhaust system pipes

410

13Cr

Precipitation Hardened stainless steel

Precipitation Hardened stainless steel is magnetic and heat treatable to high strength; therefore, it has a very high strength-to-weight ratio with good corrosion resistance.

It is used in making aerospace components and springs.

17-7PH, 17-4PH are examples of Precipitation Hardened stainless steel.

Duplex / Super Duplex stainless steel

Duplex and Super Duplex stainless steel contain both Austenite and Ferrite in the microstructure.

Because of its structure, this grade offers benefits of both Austenite & Ferrite stainless steel.

Good resistance to pitting and crevice corrosion.

High strength and high resistance to stress corrosion cracking.

Used in the seawater system, heat exchanger, and structural application

EX- UNS S32205, S31803, and S32760 are Duplex and Super Duplex stainless steel examples. Refer to the chart given below.

Grade

Alloy Component

Characteristics & Application

329J3L

22Cr-5Ni-3Mo-0.15N

High strength, high corrosion resistance. Use in various heat exchanger tubes

329J4L

25Cr-7Ni-3Mo-0.2N

S31500

18.5Cr-5Ni-2.7Mo

S32205

22.5Cr-6Ni-3Mo-0.2N

S32750

25Cr-7Ni-4Mo-0.3N

High strength, high corrosion resistance. Use in seawater desalination plant pipes

Commonly used stainless Steel ASTM Material Grades

ASTM A1016-04a Standard specification for general requirements for ferritic alloy steel, austenitic alloy steel, and stainless steel tubes

ASTM A213 Seamless ferritic and austenitic alloy steel boiler, superheater and heat exchanger tubes

ASTM A240 Standard Specification for chromium and chromium-nickel stainless steel pipe for pressure vessels and for general applications

ASTM A268 Seamless and welded ferritic and martensitic stainless steel tubing for general service

ASTM A269 Seamless and welded austenitic stainless steel tubing for general service

ASTM A312 Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes

ASTM A358 Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipe for High-Temperature Service

ASTM A376 Seamless Austenitic Steel Pipe for High-Temperature Central-Station Service

ASTM A409 Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature Service

ASTM A451 Centrifugally Cast Austenitic Steel Pipe for High-Temperature Service

ASTM A790 Seamless and Welded Ferritic /Austenitic Stainless Steel Pipe

ASTM A813 Single- or Double-Welded Austenitic Stainless Steel Pipe

ASTM A814 Cold-Worked Welded Austenitic Stainless Steel Pipe

ASTM A872 Centrifugally Cast Ferritic /Austenitic Stainless Steel Pipe for Corrosive Environments

ASTM A928 Ferritic /Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal

ASTM A943 Spray-Formed Seamless Austenitic Stainless Steel Pipe

ASTM A949 Spray-Formed Seamless Ferritic /Austenitic Stainless Steel Pipe

ASTM A954 Austenitic Chromium-Nickel-Silicon Alloy Steel Seamless and Welded Pipe

ASTM A999 General Requirements for Alloy and Stainless Steel Pipe