Alloy 718

UNS N07718 : ASTM B637 Grade 630 (VO2.04) : AMS 5662, 5663 & 5664

General scope

Alloy 718, a nickel based superalloy, developed initially for use in rotating parts in aerospace and gas turbine applications, has become the preferred material for the manufacture of Wellhead Components, Auxiliary and Down Hole Tools, and Sub-Surface Safety Valves.

The alloy also possesses excellent sub zero toughness and resistance to hydrogen embrittlement, both factors which can be as important as strength and corrosion resistance. Normally supplied using a 'double vacuum melt' process - either VIM/VAR (vacuum induction melting, followed by vacuum arc remelting), or VIM/ESR (vacuum induction melting, followed by electro slag refining), though an air melt and double VAR melting practice is also permitted by many material specifications.

Strength levels up to 150 KSI 0.2% PS can be achieved by either careful heat treatment and/or a restricted chemical analysis.

Chemical composition

C Si Mn P S Cr Ni Mo Cu NbCbTa Ti Al B Fe
Min 17.00 50.00 2.80 4.75 0.65 0.20 0.00
Max 0.08 0.35 0.35 0.015 0.015 21.00 55.00 3.30 0.30 5.50 1.15 0.80 0.01 0.00

Mechanical properties

Condition: Solution Annealed and Age Hardened.

NACE MR0175 limits hardness to 40 HRC.
U.T.S 150 KSI Min (1034 N/mm2)
0.2% Proof Stress 120 KSI Min (827 N/mm2)
Elongation 20 %
Red of Area 25 %
CVN Impacts @ -60°C (-75°F) 40 Joules (30 ft-lbf)
Size range: 1”∅ - 14”∅

Primarily manufactured in:

  • Dubai, UAE
  • Edmonton, Canada
  • Houston, Texas
  • Sheffield, England
  • Singapore