UNS N09925 / INCOLOY 925 Special Alloys For Petrochemical Industry Age Hardening Heat Treatment

Corrosion resistant alloy UNS N09925, INCOLOY 925 for down hole and surface gas well components

PRODUCT

Corrosion resistant alloy UNS N09925, INCOLOY 925 for down hole and surface gas well components

CHEMICAL COMPOSITION

PRODUCT FORMS

Tubular product, pipe fitting, round bar, long shaft, flat bar, tool joint and packer, fastener, ring, forging, etc

OVERVIEW

Alloy 925 is an austenitic nickel-iron-chromium alloy made precipitation hardenable by additions of titanium and aluminum. The precipitation hardening (age hardening) heat treatment causes precipitation of gamma prime phase, Ni3(Al,Ti). The phase greatly increases both the hardness and strength of the alloy.

Alloy 925 is an age-hardenable nickel-iron-chromium alloy with additions of molybdenum, copper, titanium and aluminum. The alloy’s chemical composition is designed to provide a combination of high strength and excellent corrosion resistance. The nickel content is sufficient for protection against chloride-ion stress-corrosion cracking. The nickel, in conjunction with the molybdenum and copper, also gives outstanding resistance to reducing chemicals. The molybdenum aids resistance to pitting and crevice corrosion. The alloy’s chromium content provides resistance to oxidizing environments. The titanium and aluminum additions cause a strengthening reaction during heat treatment.

APPLICATION

Alloy 925 is used in various applications requiring a combination of high strength and corrosion resistance. Because of the alloy’s resistance to sulfide stress cracking and stress corrosion cracking in “sour” (H₂S containing) crude oil and natural gas, it is used for down-hole and surface gas-well components including tubular products, valves, hangers, landing nipples, tool joints and packers. The alloy is also useful for fasteners, marine and pump shafting and high-strength piping systems.

PHYSICAL PROPERTIES

Density:8.08 g/cm³

Melting point:1311-1366℃

MECHANICAL PROPERTIES

Mechanical properties at room temperature of solution annealed and solution annealed plus aged products are given in Table 2.

Mechanical properties limits for specification purposes are shown in Table 3.

Table 2 Tensile properties

*All values meet the requirements of NACE Standard MR0175.

Table 3 Mechanical property limits, Solution annealed and aged

1 Charpy V-Notch impact tests performed at -75℉(-60℃), in accordance with ASTM E23. Capability of meeting the strengths shown at room temperature is guaranteed.

2 Hardness testing in accordance with ASTM E18.

CORROSION RESISTANCE

Alloy 925 has a high level of corrosion resistance. In both reducing and oxidizing environments, the alloy resists general corrosion, pitting, crevice corrosion, intergranular corrosion and stress corrosion cracking. Some environments in which alloy 925 is particularly useful are “sour” (H2S containing) crude oil and natural gas, sulfuric acid, phosphoric acid, and seawater.

HOT & COLD FORMING

The hot working range for the alloy is 1600-2150℉(870-1175℃). At temperatures up to 2000℉(1095℃), alloy 925 has hot working characteristics similar to those of Incoloy 825. For maximum corrosion resistance and highest strength after direct aging, final hot working should be done in the 1600-1800℉(870-980℃) range.

The cold forming behavior of alloy 925 is similar to that of Incoloy 825 except that alloy 925 has a higher work hardening rate.

MACHINING

Alloy 925 is an age hardenable alloy with good machinability in the solution-annealed or aged conditions. Rigid tools with positive rake angles and techniques that minimize work hardening of the material are required. Cemented carbide tools produce the highest cutting rates and are recommended for most turning operations involving uninterrupted cuts. High speed steel tools may be used for interrupted cuts, finishing to close tolerances, finishing with the smoothest surfaces, and cutting with the least amount of work hardening. Best results are obtained by rough machining before age hardening and finishing after heat treatment.

HEAT TREATMENT

Solution annealing in preparation for age hardening should be done at 1800-1900℉(980-1040℃) for a minimum of 30 min and a maximum of 4 h. Cool at a rate equivalent to air cooling, or faster, for sizes of 1 in (25 mm) or under. Water quench all sizes over 1 in (25 mm).

The following age hardening treatment is normally used:

1350-1380℉(732-749℃)/6-9 h, FC to 1150℉(621℃), hold at 1150℉(621℃) ± 15℉ (8℃) for a total aging time of 18 h. Cool at a rate equivalent to air cooling, or faster.

STANDARD SPECIFICATION

NACE MR-01-75

ASME Boiler and Pressure Vessel Code Case 2218 Section VIII Division 1

COMPETITIVE ADVANTAGE:

(1) More than 50 years experience of research and develop in high temperature alloy, corrosion resistance alloy, precision alloy, refractory alloy, rare metal and precious metal material and products.
(2) 6 state key laboratories and calibration center.
(3) Hundreds of patent technologies.
(4) Excellent performance when running in oil-gas well several tens of thousands of meters deep.

(5) We have terminal customers like Baker Hughes, Halliburton, China national offshore oil corporation LTD (CNOOC), etc.

DESCRIPTION:

BUSINESS TERM