Project Description

Introduction

N07716 Alloy 716 round bar product
N07716 / Alloy 716 Round Bar

N07716, commercially known as Alloy 716 (also Custom Age 625 PLUS / Alloy 625+), is a precipitation-hardenable Ni-Cr-Mo-Nb superalloy. It uniquely combines the high strength of Alloy 718 with the superior corrosion resistance of Alloy 625. Primarily used in the oil & gas, chemical processing, and marine industries — especially in H₂S-rich sour environments, deep-well completions, and seawater-exposed subsea systems. Governed by API 6A CRA and NACE MR0175/ISO 15156 for critical service components.

Similar Grades & Standards

Grade / Trade Name UNS Key Standards Relationship
Alloy 716 / 625+ (this grade) N07716 ASTM B805; API 6A CRA; NACE MR0175 / ISO 15156 —
Inconel 725 N07725 ASTM B805; API 6A CRA Same Ni-Cr-Mo-Nb family; sour service alternative
Inconel 718 N07718 ASTM B637; AMS 5662 / 5663; EN 2.4668 Higher strength benchmark; lower corrosion resistance
Inconel 625 N06625 ASTM B446; AMS 5666; EN 2.4856 Corrosion resistance reference; lower strength

No direct EN/DIN/JIS/GOST equivalents. N07716 is identified primarily by UNS, ASTM, and API designations.

Applications

Industry Segment Specific Component Names
Oil & Gas — Wellhead Valve bodies, bonnets, stems, seats, Christmas tree assemblies, gate valve trim
Oil & Gas — Downhole Tubing hangers, packers, SSV/SSSV, completion tools, water injection screens
Subsea & Offshore Subsea fasteners, connector bolts, structural tie-back components, production manifold hardware
Piping & Pressure Systems Flanges, couplings, high-pressure fittings (rated to 20,000 psi+)
Chemical / Marine Heat exchanger tubes, pump shafts, impellers, seawater-exposed structural fasteners

Supply Forms & Sizes

Form Size / Range Governing Standard
Forged Round Bar Φ 80 – 1,200 mm ASTM B805 / API 6A CRA
Rolled Round Bar Φ 10 – 300 mm ASTM B805
Flat Bar / Plate Custom width × thickness ASTM B805 / API 6A CRA
Tube / Pipe Seamless; custom OD & WT Project specification
Wire Cold finished; various diameters ASTM B805
Forgings (rings, discs, blocks) Custom shapes per drawing API 6A CRA

Supplied solution annealed (SA) or solution annealed + aged (SA+A). Certificates per EN 10204 3.1 / 3.2 available.

Chemical Composition

Per ASTM B805 / API 6A CRA (wt%)

Element Min % Max % Element Min % Max %
Ni 59.0 63.0 Al — 0.35
Cr 19.0 22.0 C — 0.030
Mo 7.00 9.50 Si — 0.20
Nb + Ta 2.75 4.00 Mn — 0.20
Ti 1.00 1.60 Fe Balance
P — 0.015 S — 0.010

Mechanical Properties

Per ASTM B805, round bar, room temperature. UTS = tensile strength; YS = yield strength; El = elongation; RA = reduction of area.

Heat Treatment Condition UTS (MPa) min YS 0.2% (MPa) min El (%) min RA (%) min
Solution Annealed — 1025°C, water quench 758 310 30 40
Sol. Annealed + Aged — 732°C / 8 h → furnace cool to 621–649°C / 8 h → air cool 1137 827 20 35

API 6A CRA defines two strength classes: 120K (min 827 MPa UTS) and 140K (min 965 MPa UTS). Hardness limited to ≤ 40 HRC per NACE MR0175 / ISO 15156 for sour service. The aging treatment precipitates strengthening γ′ and γ″ phases within the nickel matrix.