CORROSION RESISTANT STEEL GRADES

MARTENSITIC

A protective passive oxide film can develop on steels with chromium contents above 12%, imparting to these steels “stainless” characteristics. By maintaining a suitable composition balance between carbon and chromium, a series of high strength stainless steels are produced (R23-R23XHC).

Components cast in these alloys meet specific hardness and wear resistance criteria through closely controlled heat treatment practices. Alloy toughness and versatility are enhanced by additions of nickel and molybdenum (R24).

PRECIPITATION HARDENING

Strength and corrosion resistance superior to many martensitic stainless steel alloys is achieved by precipitation hardening a low carbon martensitic or semi-martensitic stainless steel (R27-R28). This is accomplished by accurate alloying and a low temperature heat treatment, allowing machined parts to be age hardened with only minimal distortion and scaling. Depending upon the particular alloy composition and heat treatment programme, precipitation hardening stainless steels can be supplied with appropriate hardness differentials to avoid galling and seizing during metal to metal contact

AUSTENITIC

Austenitic stainless steels are very tough and essentially non-magnetic alloys that are alloyed to produce resistance to corrosion in a variety of environments.

The basic 18% chromium/10% nickel grade (R31) has a very good corrosion resistance in many applications. This alloy can be refined (R31LC) or alloyed with molybdenum (R33,R34) for enhanced corrosion resistance or modified for improved welding (R30) and machining (R32) characteristics. Increasing nickel content and alloying with molybdenum and copper results in greatly improved corrosion resistance in more aggressive environments such as hot sulphuric acid (R36,R37).

DUPLEX

Duplex stainless steels comprise a mixture of ferrite and austenite, producing a alloy with many of the advantages offered by both structures (R29). They generally have comparable or better corrosion resistance to austenitic steels, with more than twice the yield strength, and are especially resistant to pitting corrosion and stress corrosion cracking in chloride environments.

Duplex alloys are made to a wide range of internationally recognised and proprietary specifications, through precise control of alloying content of both primary and trace elements and tailored heat treatment. Thus a series of duplex alloys develops with each grade processing specific characteristics such as Pitting Resistance Equivalent, yield strength and ferrite austenite ratio to suit a particular application.

NICKEL AND COBALT ALLOYS

The 99.5% cast nickel grade (R48) is designed to resist hot caustic solutions and can be alloyed to increase strength. Nickel-copper Monel type alloys (R47) have very good resistance to chloride corrosion. This grade can be supplied with additional silicon and age hardened (R47S) for increased strength where erosion-corrosion and galling occur in chloride containing media. The nickel-molybdenum-chromium (R39) Hastelloy type grades provide unique corrosion resistance to hydrochloric, phosphoric and hydrofluoric acid. QC R39 can additionally be alloyed with one or a combination of tungsten, vanadium, niobium, copper, tin and bismuth to produce metals with increased strength, high temperature capabilities, improved corrosion resistance and anti-galling properties.

STAINLESS STEEL GRADES

R22 Grade 420F
R23 AS 2074-H3A,B, A743 CA-15
R23HC A743-CA40
R23XHC A743-CA40
R24 AS 2074-H3C, A743-CA6NM
R25VHC AISI TYPE 440C
R26 AISI TYPE 431
R26HC Q.C. Special Alloy
R27 AS 2074-H7B, A447-CB7Cu 2
R28 AS 2074-H7A, A447-CB7Cu 1
R29-1A A744-CD4MCu, A890-1A
R29-4A A890-4A
R29-5A A890-5A
R30 AS 2074-H5C, A351-CF8C
R31 AS 2074-H5A, A351-CF8
R31LC A351-CF3
R32 AS 2074-H5AM,BM, A743-CF16F
R33 AS 2074-H6B, A351-CF8M
R33 AS 2074-H6B, A351-CF8M
R33LC A351-CF3M
R33Nb AS 2074-H6C
R34 AS 2074-H6A, A351-CG8M
R36 AS 2074-H9A, A744-CN7M
R37 A744-CN7MS
R39 A494-CW6M, INCOLOY C-276
R40 A494-CW12MW, INCOLOY C-276
R42 A494-N7M, HASTELLOY B-2
R43 Q.C. Alloy
R47 A494-M35-1, MONEL 400
R48 A494-CZ100, NICKEL 200

AUSTENITIC STAINLESS STEELS

Austenitic stainless steels are very tough and essentially non-magnetic alloys that are alloyed to produce resistance to corrosion in a variety of environments.

The basic 18% chromium/10% nickel grade (R31) has a very good corrosion resistance in many applications. This alloy can be refined (R31LC) or alloyed with molybdenum (R33,R34) for enhanced corrosion resistance or modified for improved welding (R30) and machining (R32) characteristics. Increasing nickel content and alloying with molybdenum and copper results in greatly improved corrosion resistance in more aggressive environments such as hot sulphuric acid (R36,R37).

 AUSTENITIC STAINLESS GRADES

 
R30 AS 2074-H5C, A351-CF8C
R31 AS 2074-H5A, A351-CF8
R31LC A351-CF3
R32 AS 2074-H5AM,BM, A743-CF16F
R33 AS 2074-H6B, A351-CF8M
R33 AS 2074-H6B, A351-CF8M
R33LC A351-CF3M
R33Nb AS 2074-H6C
R34 AS 2074-H6A, A351-CG8M
R36 AS 2074-H9A, A744-CN7M
R37 A744-CN7MS

DUPLEX STAINLESS STEELS

Duplex stainless steels comprise a mixture of ferrite and austenite, producing a alloy with many of the advantages offered by both structures. They generally have comparable or better corrosion resistance to austenitic steels, with more than twice the yield strength, and are especially resistant to pitting corrosion and stress corrosion cracking in chloride environments.

Duplex stainless steels have for years been providing excellent service in seawater on offshore platforms and in a wide variety of other chloride containing environments.

The pitting resistance equivalent number (PREN) is an empirical guide to the grading of alloys  for resistance to seawater. Duplex stainless steel has been designed to exceed the commonly specified PREN of 40 and provide, for example, castings suitable for pumps and valves on offshore oil and gas platforms.

DUPLEX GRADES

R29-1A A744-CD4MCu, A890-1A
R29-4A A890-4A
R29-5A A890-5A

Fatigue Characteristics: These alloys have superior resistance to fatigue and corrosion fatigue.

Machine and Weldability: Duplex and Super Duplex alloys are readily machined. Surface work hardening can occur. These alloys  are also readily weldable.

Standards:

  • Casting specifications UNS J93404, J92205 and J93370/73
  • ASTM A890 Grades 1A, 1C, 4A, and 5A
  • Listed in MRO175 for sour service.

Applications:

Duplex and Super Duplex are a high-tech alloys for use in many situations where safer more cost effective, high strength, corrosion resistant  alloys are needed. Some of the various applications are:

  • Worldwide use on offshore development.
  • Marine environments.
  • Seawater systems and cooling.
  • Oil and gas industry.
  • Process systems in Chemical plants.
  • Refineries and Petrochemical plants.
  • Fire water systems.
  • Pump and valve castings.

DaviesBaird would welcome the opportunity of having our experienced team of foundry engineers and metallurgists work with you to provide the most suitable grade for your application.

MARTENSITIC STAINLESS STEELS

A protective passive oxide film can develop on steels with chromium contents above 12%, imparting to these steels “stainless” characteristics. By maintaining a suitable composition balance between carbon and chromium, a series of high strength stainless steels are produced (R23-R23XHC).

Components cast in these alloys meet specific hardness and wear resistance criteria through closely controlled heat treatment practices. Alloy toughness and versatility are enhanced by additions of nickel and molybdenum (R24).

 MARTENSITIC GRADES

R23 AS 2074-H3A,B, A743 CA-15
R23HC A743-CA40
R23XHC A743-CA40
R24 AS 2074-H3C, A743-CA6NM
R25VHC AISI TYPE 440C

PRECIPITATION HARDENING

Strength and corrosion resistance superior to many martensitic stainless steel alloys is achieved by precipitation hardening a low carbon martensitic or semi-martensitic stainless steel. This is accomplished by accurate alloying and a low temperature heat treatment, allowing machined parts to be age hardened with only minimal distortion and scaling. Depending upon the particular alloy composition and heat treatment programme, precipitation hardening stainless steels can be supplied with appropriate hardness differentials to avoid galling and seizing during metal to metal contact

 PRECIPITATION HARDENING GRADES

R27 AS 2074-H7B, A447-CB7Cu 2
R28 AS 2074-H7A, A447-CB7Cu 1