Engineered stainless: 2x stronger yield than 316 stainless steel
Decent general corrosion & cracking resistance
Chemistry & Specs: Duplex 2205, Super Duplex 2507, Zeron 100
ASTM A1082 fasteners
Insight on Duplex 2205, Super Duplex 2507 and Zeron 100
Strength Properties: tensile, yield & elongation charts
Duplex stainless steel fastener styles
Fastener availability and lead time
Duplex Screw FAQ of the Week
Datasheet for Super Duplex 2507
Datasheet for Duplex 2205
Duplex Fastener Overview
Duplex 2205 and Super Duplex 2507 (UNS S32205 / UNS S32750) stainless steel fasteners are characterized by their high yield strength, which is twice that of annealed austenitic stainless steels, like 304 and 316. In addition, Duplex steels offer improved corrosion protection compared to 300 series stainless, especially in terms of localized corrosion such as crevice and pitting, as well as stress corrosion cracking. In general, Duplex steel bolts are a great step up from 300 series stainless.
The main difference between the Duplex alloys is that 2507 offers higher strength and better corrosion resistance compared to Duplex 2205.
• Duplex 2205 (1.4462): Higher strength and corrosion resistance than 300 series stainless.
• Super Duplex 2507 (1.4410): Improved corrosion resistance and strength compared to 2205.
Mechanical Properties
Duplex 2205 bolts provide a typical UTS of 110ksi and a yield strength of 80ksi, whereas Super Duplex bolts offer slightly higher strength at 125ksi UTS and 82ksi yield. In general, Duplex fasteners have significantly better toughness and ductility than ferritic grades of steel, but not the levels of austenitic grades. Usage of both a Duplex screw and Super Duplex stainless steel screw should be limited to temperatures below 570°F, as extended exposure to elevated temperatures can embrittle this material.
Key properties:
• High strength and fatigue resistance
• Good toughness & ductility
• Temperature usage limit: 570°F
• Low thermal expansion
Corrosion Resistance
Though Duplex steel screws are not ideal for harsh chemical environments, they do offer better corrosion resistance than 300 series stainless steel and are ideal for saltwater and chloride applications. Duplex bolts offer resistance to:
• Saltwater: salt air, brackish water and marine environments.
• Localized chloride corrosion: pitting and crevice corrosion as well as stress corrosion cracking.
• Sulfide stress corrosion resistance
• Oxidation
Which Duplex Steel is Best for Your Application?
The most common grades of Duplex steel fasteners are Duplex 2205 and Super Duplex 2507. If you are still not sure, our engineering team is here to offer their expertise on which grade will meet the specific requirements of your application. We also offer other resources including Duplex Torque Specs.
Duplex Steel Fastener Stock and Availability
Stock
Common sizes of Duplex fasteners (both metric and standard) are kept in stock in both 2205 and 2507, including hex head bolts, hex nuts, lock washers and flat washers. Additionally any size could be made to order.
Custom Availability
We can make both common and custom-to-print Duplex fasteners. Typically, we require a minimum quantity of approximately 25 pieces, depending on the fastener size and type. We also can provide fasteners in Zeron 100, F55 and other grades. The lead time for Duplex fasteners is about 4 weeks. Be sure to contact us for specific lead times and expediting needs.
• Diameter sizes: Standard #00 – 4” in diameter / Metric M1.2 – M48
• Threads: UNC, UNF, UNJ, UNR, Rolled or Cut
• Minimum Volume – Typically 25pcs depending on size and stock
• All ANSI/ASME and DIN / ISO standards
• NACE MR0175, ASTM, ASME, MIL specifications, DFAR and Domestic available
Expediting Options
Let us know if you have lead time requirements that require a rush order so that we can accommodate them.
Duplex Fastener Styles
| Duplex Screws | 12 Point Screws, Button Head Cap Screws, Flat Head Screws, Hex Head Cap Screws, Pan Head Screws, Security Screws, Self Drilling Screws, Set Screws, Socket Head Cap Screws, Vented Screws |
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| Duplex Bolts | Hex Head Bolts, Shoulder Bolts, Wedge Anchor Bolts | • DIN 931 • DIN 933 • ISO 4014 • ISO 4017 • ISO 7370 | ||
| Duplex Nuts | Hex Nuts, Lock Nuts | • DIN 439 / ISO 4035 • DIN 934 / ISO 4032 • DIN 985 / ISO 7040 • DIN 986 • DIN 980 / ISO 7042 / ISO 19513 • DIN 6923 / ISO 4161 | ||
| Duplex Studs/Rod | Studs, Threaded Rod, Weld Studs | • DIN 975 • DIN 976 | ||
| Duplex Washers | Flat Washers, Lock Washer | • DIN 125 / ISO 7089 / ISO 7090 |
Common Duplex Bolt Grades
Duplex Alloy 2205 (1.4462)
Duplex 2205, UNS S32205, is a stainless steel material, whose “Duplex” name is derived from the mixed microstructure which contains roughly equal portions of ferrite and austenite. This grade is the most popular variety and this two-phase material is a significant upgrade from 316 stainless steel in terms of both yield strength and corrosion resistance.
DUPLEX 2205 SPECIFICATIONS: ASME SA 182, ASME SA 240, ASME SA 479, ASME SA 789, ASME SA 789 Section IV Code Case 2603, ASTM A 240, ASTM A 276 Condition A, ASTM A 276 Condition S, ASTM A 479, ASTM A 790, NACE MR0175/ISO 15156, NORSOK MDS D45 Grade F51, UNS S31803, UNS S32205, W. NR./EN 1.4462, Werkstoff 1.4462 Duplex
Duplex 2205 | Fe | Cr | Ni | Mo | Mn | Si | N | P | C | S |
Min% | - | 22.0 | 4.5 | 3.0 | - | - | - | - | - | - |
Max % | Bal | 23.0 | 6.5 | 3.5 | 2.0 | 1.0 | 0.20 | 0.030 | 0.03 | 0.020 |
Super Duplex Alloy 2507 (1.4410)
Super Duplex 2507, UNS S32750, is a two-phase stainless steel and is particularly well suited for use in environments such as warm chlorinated seawater and acidic, chloride containing media. It has similiar properties to Duplex 2205 but is more corrosion resistant and performs well in moderately corrosive environments.
SUPER DUPLEX 2507 SPECIFICATIONS: EN 10216-5, ASTM A789; A790, ASTM A182 ASTM A182, ASTM A815, ASTM A240, EN 10088-2, ASTM A479, EN 10088-3 EN 10088, ISO 15156-3, NACE MR0175, Werkstoff 1.4410 S.Duplex
Super Duplex2507 | Fe | Cr | Ni | Mo | Mn | Si | P | C | S |
Typical | - | 25.0 | 7 | 4 | ≤1.2 | | ≤0.8 | ≤0.015 | ≤0.030 | ≤0.015 |
Zeron 100 / F55
Zeron 100 fasteners are made of a high-grade Super Duplex steel alloy that is designed for more aggressive corrosion than grades 2205 and 2507. Zeron 100 (also known as F55) has added copper and tungsten (compared to grade 2507) for improved corrosion resistance. Zeron 100 bolts offer mechanical strength similar to Duplex 2205 with tensile strength of 109ksi and yield strength of 80ksi. Zeron 100 fasteners have a maximum usable temperature of about 572˚F.
• High level of resistance to pitting and crevice corrosion in warm seawater
• Excellent chloride-induced stress corrosion cracking and sulfide-stress cracking in sour-gas conditions
• Better resistance to alkalis and acids than other Duplex grades
• Improved resistance to fatigue and erosion corrosion that any other stainless steel alloy
Applications
• Marine and desalination rely on Zeron 100 bolts for their high level of seawater corrosion resistance.
• Zeron 100 is used in oil & gas, as well as flue gas desulfurization to protect from sulphide-stress cracking.
• For resistance to chlorides, Zeron 100 fasteners are used in pulp & paper bleaching processes.
ZERON 100/F55 SPECIFICATIONS: ASTM A 182, ASTM A 182 (Grade F55), ASTM A 240, ASTM A 276, ASTM A 473, ASTM A 479, ASTM A 790, ASTM A 815, ASTM A314, NORSOK MDS 055, UNS S32760, W. Nr./EN 1.4501, Werkstoff 1.4501
Zeron 100 | Fe | Cr | Ni | Mo | Cu | W | Mn | Si | N | P | C | S |
Min% | - | 24.0 | 6 | 3.0 | 0.5 | 0.5 | - | - | - | - | - | - |
Max% | Bal | 26.0 | 8.0 | 4.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.30 | 0.030 | 0.03 | 0.010 |
12 Point Screws
Button Head Cap Screws
Flat Head Screws
Hex Head Cap Screws
Pan Head Screws
Security Screws
Self Drilling Screws
Set Screws
Socket Head Cap Screws
Vented Screws
Hex Head Bolts
Shoulder Bolts
Wedge Anchor Bolts
Hex Nuts
Lock Nuts
Studs
Threaded Rod
Weld Studs
Flat Washers
Lock Washers