High Nickel Alloys

TechBolt - Super Duplex/ Duplex Steel:

Duplex alloys are essentially a compromise possessing some of the ferritic stress corrosion resistance and much of the superior formability of the common austenitic stainless alloys, at a cost saving over the high nickel alloys.

The Various Alloys:

The development of the Duplex stainless steels has continued, graded for their corrosion performance depending on their alloy content. Today, modern duplex stainless steel can be divided into four groups:

• Lean Duplex such as 2304, which contains no deliberate Mo addition
• 2205,the work-horse grade accounting for more than 80% of duplex usage.
• 25 Cr Duplex such as Alloy 255 and DP-3
• Super Duplex; with 25-26 Cr and increased MO and N compared with 25 Cr grades, including grades such as 2507, Zeron 100. UR 52N+, and DP-3W.

SUPER HIGH TEMPERATURE RESISTANT BOLT MATERIAL

This material is considered as suitable for bolts to be used as temperature around 1200 ^oF (650^o C) and the material has superior resistance to oxidation and shrinkage. The grades of steel available as per ASTMA453 are Grade 660 (UNS S66286) also known as A-286; 651 (UNS 63198) also known as 19-9 DL; Grade 662 (UNS 66220) also known as Discaloy & Grade 665 (UNS66545) also known as W545

Precipitation hardening stainless steels are characterized into one of the three groups based on their final microstructures after heat treatments. The three types are martensite (e.g 17-4 PH), semi-austenitic (e.g. 17-7 PH), and austenitic (e.g. A-286).

The development of the Duplex stainless steels has continued, graded for their corrosion performance depending on their alloy content. Today, modern duplex stainless steel can be divided into four groups: