NiCr15Fe7Ti2Al

01 What NiCr15Fe7Ti2Al is, and why it is forged

NiCr15Fe7Ti2Al gets its strength from heat treatment rather than from cold work. The composition is built around a nickel matrix of at least 70 %, with 14 to 17 % chromium for oxidation and corrosion resistance, plus controlled additions of titanium, aluminium and niobium.

During ageing those additions come out of solution as fine gamma-prime Ni₃(Ti,Al) particles. The particles obstruct dislocation movement, so the alloy holds its strength and resists stress relaxation at temperatures where austenitic stainless steels have already softened. Typical use is in highly stressed parts running at intermediate temperature: turbine components, high-strength bolting, springs, valve internals and rotating shafts.

The alloy is costly by weight and slow to machine from solid, so it is normally bought as a forging rather than as bar stock cut down to size. Open-die forging works the ingot close to the finished envelope. That reduces the buy-to-fly ratio, keeps grain flow following the part contour, and develops the internal soundness that pressure and rotating equipment codes call for.

02 Chemical composition of NiCr15Fe7Ti2Al

Composition limits in weight percent. Nickel is the balance and includes incidental cobalt where the specification permits it.

The titanium and aluminium range controls strength. Ti and Al together determine how much gamma-prime forms during ageing. Carbon is held to 0.08 % maximum to limit grain-boundary carbides. Melt analysis is reported on the mill certificate for every heat, and product analysis is available on request.

03 Mechanical and physical properties

The values above are acceptance minima for the condition shown. Properties achieved in a finished forging depend on the heat-treatment temper, the forging ratio and the section size, and are agreed at order stage. Test-piece location and orientation are set out in the inspection plan before production starts. Where a specification names a temper, for example the conditions in AMS 5667 or AMS 5671, the forging is heat treated and tested to that specification.

Typical published values for this grade, given for design orientation only. Service temperature limits depend on stress level, exposure time and the governing design code. Confirm against the code applicable to your equipment.

04 Forged forms and size capability

All shapes below are produced to customer drawing in NiCr15Fe7Ti2Al. Open-die forging uses flat or simple contoured dies instead of a closed impression die, so there is no tooling to pay for. A single prototype or a one-off replacement part costs the same per piece as it would in a batch.

• Seamless rolled rings

  Ring-rolled from a pierced preform for continuous circumferential grain flow. Used for bearing races, turbine casings, flanged connections and valve seat rings.

  OD 200 to 3,000 mm

• Forged rings and hollow sections

  Upset and punched rings where the wall-to-diameter ratio falls outside the ring-rolling envelope, plus hollow bars and thick-wall cylinders.

  Wall to 800 mm

• Discs and blanks

  Upset discs for turbine wheels, blind flanges, gear blanks and machining blanks, with ultrasonic inspection through the full section.

  Ø to 2,000 mm

• Shafts and spindles

  Drawn-out shafts, stepped shafts, eccentric shafts and crankshafts for pumps, compressors and process machinery.

  Ø 80 to 1,000 mm · L to 8,000 mm

• Round bars and billets

  Forged round bar and forging stock for onward machining, supplied rough-turned, peeled or black as required.

  Ø 80 to 800 mm

• Flanges and tube sheets

  Weld-neck, blind, slip-on and special flanges, plus solid forged tube sheets for shell and tube heat exchangers.

  Ø to 2,500 mm

• Sleeves and bushings

  Forged sleeves, bushings, wear rings and liners for subsea, downhole and rotating equipment.

  Single piece to batch

• Valve components

  Valve bodies, bonnets, stems, seat rings, blocks and gate wedges for ball, gate, globe, check and plug valves.

  To API and customer specs

05 Melting and forging route

NiCr15Fe7Ti2Al has a narrow forging window, work hardens quickly, and its titanium and aluminium oxidise readily. The melting method, the reheat schedule and the number of forging operations are fixed before production starts and recorded on the certificate.

1. Melting by EAF + VOD + ESR

   Electric arc melting followed by vacuum oxygen decarburisation, then electroslag remelting. ESR removes the non-metallic inclusions and centre-line segregation that would otherwise show up as ultrasonic indications in a heavy section.

2. Ingot inspection and conditioning

   Ingot chemistry verified against the heat certificate, surface conditioned, and the hot top and bottom discard removed before forging.

3. Open-die forging

   Upsetting and drawing out on a hydraulic press with a controlled reduction ratio, so the as-cast dendritic structure is broken down and the grain flow follows the finished contour. Reheats are scheduled to keep the workpiece inside the forging temperature window.

4. Ring rolling, where applicable

   For ring geometries the pierced preform is rolled to final diameter, which gives continuous circumferential grain flow with no weld or joint.

5. Solution treatment and ageing

   Solution treatment dissolves the strengthening elements into the nickel matrix. Ageing then precipitates gamma-prime Ni₃(Ti,Al). Both operations are performed in-house on calibrated, surveyed furnaces with charts retained.

6. Rough machining and NDT

   Machined to the ultrasonic test envelope, then inspected to EN 10228-3, SEP 1921 or ASTM A388 as specified. Mechanical test pieces are cut from integral or separately forged prolongations as agreed.

7. Certification and despatch

   EN 10204 3.1 certificate issued covering melt analysis, mechanical results, hardness, heat-treatment record, NDT report and dimensional inspection. Certification to 3.2 with third-party witness is arranged where required. Packing and shipment from Shanghai or Ningbo.

06 Heat treatment conditions

NiCr15Fe7Ti2Al is supplied in whichever condition the design calls for. The three routes below cover most orders. Where a specification names a temper, the forging is processed and tested to that specification instead.

• Solution treated and aged

  The general-purpose condition. High solution temperature followed by a single ageing treatment, giving the balance of strength and ductility used for most pressure and rotating equipment parts.

• Equalised and aged

  An intermediate equalising treatment before ageing, used where relaxation resistance matters more than peak tensile strength, such as springs, bolting and preloaded fasteners.

• Triple treatment

  Solution, stabilisation and precipitation stages in sequence, specified for demanding creep-rupture applications at the upper end of the temperature range.

Furnace charts, thermocouple calibration records and heat-treatment certificates are retained and issued with the material certificate. Where the customer specification fixes soak times, ramp rates or quench media, those parameters are written into the manufacturing plan and signed off before the first piece is charged.

07 Where NiCr15Fe7Ti2Al forgings are used

High-temperature strength, relaxation resistance and chromium-based corrosion resistance put this alloy into equipment where parts are both hot and highly stressed, or in contact with corrosive fluid and highly stressed.

• Pumps and rotating equipment Seamless rolled rings and forged shafts for chemical pumps and plunger pumps, where the shaft sees both corrosive fluid and cyclic loading.
• Pressure vessels and heat exchangers Forged shafts, pipes, tubes, tube sheets and flanges for pressure vessels, air receivers and shell-and-tube heat exchangers.
• Process columns and towers Forged shafts, flanges, rings and pipes for columns, towers, tanks, silos, process modules and preheaters.
• Offshore and subsea oil production Forged bushings, sleeves, discs and blanks for subsea and deepwater production systems, industrial air compressors, power generators and nitrogen generators.
• Wellhead and Christmas tree equipment Forged nozzles, eccentric shafts and body components for wellhead assemblies, processing units and crystalliser equipment.
• Valves Forged valve stems, seat rings, blocks and bodies for ball, check, globe, gate and plug valves, and for strainers.
• Power transmission and turbines Forged rings, spindles, bars and gear blanks for turbines, gas compressors, gear boxes and power transmission assemblies.
• Mills and heavy machinery Open-die forged nozzles, crankshafts and forging pieces for cement mills, sugar mills, concrete mills and mixers.
• Shipbuilding, pulp and pharmaceutical Forged wheels, manifolds and rolls for shipbuilding, heavy machinery, paper and pulp plant, and pharmaceutical and biochemical processing.

08 Testing, inspection and certification

Every NiCr15Fe7Ti2Al forging leaving the factory carries documented traceability from heat number to finished dimension.

Non-destructive testing

• Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. The acceptance class is agreed at order stage and stated on the report.
• Liquid penetrant testing to ASTM E165 or EN ISO 3452 where surface indications are critical.
• Magnetic particle testing does not apply. NiCr15Fe7Ti2Al is essentially non-magnetic in the solution-treated and aged condition.

Destructive and metallurgical testing

• Tensile testing at room and elevated temperature
• Hardness survey, Brinell or Rockwell as specified
• Charpy impact testing where the design code requires it
• Grain size and microstructure examination
• Intergranular corrosion testing on request

Certification

Material certificates are issued to EN 10204 3.1 as standard, covering melt analysis, mechanical results, heat-treatment record, NDT report and dimensional inspection. EN 10204 3.2 certification with third-party witness by TÜV, SGS, BV, Lloyd's Register or the customer nominated inspector is arranged on request. Positive material identification, hardness mapping and full traceability marking are available.

09 International designations and equivalents

Purchase drawings arrive with whichever designation the originating engineer used. All of the following refer to the same nickel-chromium superalloy.

Cross-references are given as a guide to locating the nearest grade. Composition limits, permitted tempers and test requirements differ between specifications, and between revisions of the same specification. Confirm the governing specification and revision on your purchase order. Jiangyin Jiangnan Metal supplies to the specification named on the order.

10 Frequently asked questions

11 Page details and technical enquiries

Data on this page is maintained by the technical team at Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, and reflects the composition and property limits used in production. Last reviewed 22 August 2026. Corrections and technical queries are welcome at sales@steelforgepieces.com.