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.
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STAINLESS STEEL GRADES |
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| 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).
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AUSTENITIC STAINLESS GRADES |
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| 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.
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DUPLEX GRADES |
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| 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).
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MARTENSITIC GRADES |
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| 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
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PRECIPITATION HARDENING GRADES |
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| R27 | AS 2074-H7B, A447-CB7Cu 2 |
| R28 | AS 2074-H7A, A447-CB7Cu 1 |