NiCr20Ti forgings W.Nr. 2.4951 / 2.4630 · UNS N06075 · Alloy 75 · Nimonic 75 · forged rings, flanges, shafts, discs, bars and tube sheets

What NiCr20Ti actually is

NiCr20Ti is a wrought nickel alloy carrying about 20 % chromium. Strength comes from chromium held in solid solution. There is no gamma-prime or gamma-double-prime precipitate in this grade.

The titanium content, 0.2 to 0.6 %, is not a strengthener. It combines with carbon to form MC-type carbides on the grain boundaries, and those carbides hold grain size steady through a long solution soak. For that reason the specification sets a carbon minimum of 0.08 % as well as a maximum.

For a buyer the outcome is a material that behaves predictably. Nothing over-ages in service, ductility stays where it started, and the alloy forges, machines and welds by ordinary methods. What it does not offer is high strength under sustained load. Specify NiCr20Ti where hot oxidising service and fabricability govern. Specify an age-hardened grade where creep governs.

Most of the NiCr20Ti problems that reach us start with a stress figure taken off a Nimonic 80A table. The two grades sit in the same family and the proof stress differs by roughly a factor of three, so a part sized against the wrong table comes out undersized. Send us the metal temperature, the sustained stress and the required life. We will tell you whether 75 covers it before any material is bought.

Designations, equivalents and governing standards

The same alloy reaches us under several names. Every designation below describes one material, and Jiangyin Jiangnan Metal quotes against any of them.

Cross-references are approximate. Two grades can share a nominal composition and still differ in residual limits, test temperature, heat-treatment condition or acceptance criteria. We supply against the specification written on your purchase order, and the actual heat analysis appears on the mill certificate.

Chemical composition of NiCr20Ti

The table below is the delivery specification we work to for NiCr20Ti forgings supplied under DIN 17744. Figures are weight percent.

Some published versions of the grade allow wider bands, with carbon to 0.15 % and silicon and manganese to 1.00 % each, because W.Nr. 2.4951 and 2.4630 are written to slightly different limits. The table above is the window we melt to. Tighter customer limits, a restricted cobalt content for nuclear work being the usual case, should appear on the enquiry so they can be set at the melting stage rather than found after forging.

Physical properties

Thermal conductivity of 13 W/m·K is roughly a quarter of carbon steel. That figure sets the ingot soak time and explains why heat stays in the cutting zone during machining.

Mechanical properties

Room temperature, forged and solution annealed

These are acceptance minimums for forgings, not typical results. Published minima for other product forms are commonly quoted as R_p0.2 ≥ 235 MPa, R_m ≥ 640 MPa and A₅ ≥ 26 %. Heavy sections may be agreed at reduced values by prior agreement. Note the proof stress: 240 MPa is about a third of what an aged Nimonic 80A delivers, and that gap decides between the two grades on most enquiries.

Service temperature envelope

Four figures circulate as the maximum temperature for NiCr20Ti and each answers a different question. Scaling stops the alloy near 1200 °C. Useful mechanical properties run out around 1000 °C. Sustained stress brings the working ceiling down to 600 – 650 °C. Below about 550 °C an austenitic stainless such as 321 or 347 will usually do the same job cheaper. Establish which of the four governs your part before comparing grades.

Heat treatment: one step, not three

NiCr20Ti does not precipitation harden. There is no stabilisation and no ageing cycle. Solution annealing is the only heat treatment applied, and the annealed condition is the delivery condition. That removes most of the schedule risk carried by age-hardened superalloys.

Forging and hot-working practice

The hot-working window runs roughly 950 to 1180 °C. At about 230 °C wide it is generous by superalloy standards, against roughly 190 °C on Waspaloy. That margin is one reason the grade suits large or awkward open-die geometries: fewer reheats, less pressure on transfer times, lower scrap risk.

• Ingot heating: slow and even. At 13 W/m·K the surface runs well ahead of the core, and a rushed soak cracks the ingot before the press touches it.
• Reduction: final reduction is controlled to reach the grain size the specification calls for. Titanium carbides do most of the pinning on this grade, but reduction sets the starting point.
• Cold work: the annealed material takes bending, spinning, drawing and roll forming, with intermediate annealing where reduction is heavy.
• Ultrasonic inspectability: a coarse or duplex grain structure fails UT acceptance to EN 10228-3. Grain control belongs to the forging shop, not to the inspection bay.

Machining and welding NiCr20Ti

Machining

NiCr20Ti cuts more like a tough austenitic stainless than like a superalloy. At 230 HB or below it is workable with standard carbide tooling, though it work-hardens under a rubbing edge and holds heat at the cutting zone. Baseline settings are rigid setups, sharp positive-rake tooling, low to moderate surface speed with a heavy constant feed, and generous through-tool coolant. Keep the tool moving; a dwell in the cut hardens the surface and ruins the next pass. Agree the proof-machining allowance at enquiry stage, because on a nickel alloy that allowance is a real cost item.

Welding

MMA, TIG and MIG all work with conventional nickel-alloy practice. This is one of the grade's main advantages over the age-hardened alloys: no strain-age cracking sensitivity, and no mandatory re-solution treatment of the assembly. W.Nr. 2.4648 or an equivalent Ni-Cr consumable is commonly used, with the exact wire chosen to suit the service environment and the applicable welding procedure specification. Joints must be clean and free of sulphur-bearing contamination before heating, as with every nickel alloy.

NiCr20Ti forged products and size range

We produce the following part families in NiCr20Ti to customer drawing, as single prototypes or as repeat production lots.

Sizes outside these ranges are quoted case by case. Send the drawing. On nickel alloys the limiting factor is usually the heat-treatment furnace and the forging reduction ratio required, not the press.

How a NiCr20Ti forging is produced here

1. Melting. EAF, then VOD, then ESR. Electric arc melting is followed by vacuum oxygen decarburisation to reach the 0.08 to 0.13 % carbon window and strip hydrogen, oxygen and nitrogen. Electroslag remelting then gives a dense ingot with low inclusion content. On a nickel alloy that will be ultrasonically inspected through a heavy section, the ESR stage is what makes a clean and consistent indication level possible.
2. Billet preparation. Ingot conditioning, cropping and ultrasonic pre-check of the input stock.
3. Open-die forging. Upsetting and drawing inside the 950 to 1180 °C window. Ring blanks are punched and rolled on the ring mill.
4. Solution annealing. About 1050 °C, air cooled, soak scaled to section, with recorded furnace charts.
5. Rough machining. Turning and boring to the agreed allowance, which gives UT-clean surfaces and shows up defects early.
6. Non-destructive testing. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 as specified, with dye penetrant on machined surfaces where required.
7. Mechanical testing. Tensile and hardness from integral or prolongation test material. Elevated-temperature tensile on request.
8. Certification and dispatch. EN 10204 3.1, or 3.2 with third-party witness. Marking, preservation and seaworthy packing.

Inspection, testing and certification

• Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, at the acceptance class named on the order.
• Liquid penetrant examination on finish-machined surfaces where the specification requires it.
• Chemical analysis. Product analysis taken from the forging, in addition to the melt analysis.
• Mechanical testing. Tensile at room temperature, elevated-temperature tensile on request, plus a hardness survey.
• Grain size and microstructure to ASTM E112 where the specification calls it out.
• Intergranular corrosion testing to ASTM A262 or ASTM G28 where the service environment justifies it.
• Certificates. EN 10204 3.1 as standard, EN 10204 3.2 with an independent inspection body such as TÜV, SGS, BV or Lloyd's when the customer requires it.

A 3.2 certificate needs the inspector present to witness the tests, so it has to be planned into the production schedule and cannot be added afterwards. Heat number, forging record, furnace chart and NDT report are compiled into one data book and issued with the shipment.

Where NiCr20Ti forgings are used

NiCr20Ti gets specified where oxidation and scaling resistance at temperature matter more than peak creep strength, and where the part still has to be fabricated, welded or machined. Typical forged components include:

• Gas turbines and thermal processing: seamless rolled rings and forged shafts for gas-turbine engineering and industrial thermal processing plant. Forged wheels, manifolds and rolls as furnace components and heat-treatment equipment, where repeated thermal cycling in air is the governing condition.
• Pressure vessels and heat exchangers: forged shafts, pipes, tubes, forged tube sheets and flanges for pressure vessels, air receivers and shell-and-tube heat exchangers.
• Process plant: forged flanges, rings and pipes in columns and towers, tanks, silos, process modules and preheaters. Forged nozzles and eccentric shafts on processing units, crystalliser equipment, wellhead and Christmas-tree assemblies.
• Oil, gas and offshore: forged bushings, sleeves, disks and discs for subsea and deepwater production systems, industrial air compressors, power generators and nitrogen generators.
• Valves: forged valve stems, valve seat rings, valve blocks and bodies for ball, check, globe, gate and plug valves and for strainers.
• Power transmission: forged rings, spindles, bars and gears for turbines, gas compressors and gearboxes.
• Nuclear and automotive: open-die forging parts, forged nozzles and crankshafts for nuclear boiler tube supports, die-casting inserts and cores, and automobile exhaust valves.

All of these have air at temperature in common. Where the atmosphere turns reducing, or chlorides are present, the chromium oxide scale that protects this alloy stops working, and an Inconel or Hastelloy grade becomes the right direction.

NiCr20Ti compared with Nimonic 80A, Inconel 600 and Inconel 601

Below about 550 °C an austenitic stainless such as 321 or 347 is usually the cheaper answer. Between 550 and 1000 °C in air at modest stress, NiCr20Ti is normally the efficient choice, since it buys oxidation resistance without the forging, machining and welding penalties of an age-hardened grade. Above about 815 °C under sustained load, the gamma-prime in Nimonic 80A carries stress that NiCr20Ti cannot. In reducing or chloride-bearing environments, move to Inconel 600 or a Hastelloy grade whatever the temperature.

We forge all four grades. If you are undecided, send the duty cycle, meaning temperature, stress and required life, rather than the grade. We will comment before quoting.

Frequently asked questions

About the supplier

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, inside the Yangtze River delta forging cluster and within reach of the ports of Shanghai and Zhangjiagang. The works produces open-die forgings and seamless rolled rings in carbon steel, alloy steel, tool steel, stainless steel and nickel-base alloys, including NiCr20Ti (2.4951 / UNS N06075), Inconel, Incoloy, Hastelloy, Nimonic, Waspaloy, Monel and Haynes grades.

Work is supplied to drawing with EN 10204 3.1 or 3.2 certification, ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, and full heat-number traceability. Enquiries reach the technical team directly on +86 189 2135 9659 or sales@steelforgepieces.com.

Related nickel alloy grades we forge

• Nimonic 75
• Nimonic 80A
• NiCr20Co13Mo4Ti3Al
• Waspaloy
• Rene 41
• Inconel 600
• Inconel 601
• Inconel 617
• Inconel 625
• Inconel 690
• Inconel 693
• Inconel 706
• Inconel 725
• Inconel X-750
• Incoloy 800
• Incoloy 800H
• Incoloy 800HT
• Incoloy 825
• Incoloy 901
• Incoloy 925
• Incoloy 926
• Incoloy 945
• Hastelloy C-276
• Hastelloy C-22
• Hastelloy X
• Haynes 25
• Haynes 188
• Haynes 230
• Monel 400
• Monel K-500
• MP35N
• Multimet N155
• Alloy 59
• Alloy 602

NiCr20Ti in other forged forms

• Forged rings
• Forged tube sheets
• Forged valve seat rings
• Forged pipes
• Forged sleeves
• Forged spindles

Data sources and citation

Composition, physical constants and heat-treatment cycles on this page follow the published mill and specification literature for UNS N06075 and W.Nr. 2.4951, in particular:

• DIN 17744, wrought nickel alloys, chemical composition. This is the delivery specification for the forgings described here. Related product forms are covered by DIN 17742, 17751 and 17752.
• Metalcor GmbH, datasheet 2.4951 / Alloy 75 / UNS N06075, for density, elastic modulus, specific heat, thermal conductivity, electrical resistivity and scaling temperature.
• SteelNumber, NiCr20Ti / 2.4951 composition and equivalents, for cross-reference data.
• EN 10204, metallic products, types of inspection documents, for the 3.1 and 3.2 certificates.
• EN 10228-3, SEP 1921 and ASTM A388 for ultrasonic examination of forgings. ASTM B637 for nickel alloy bar, forgings and forging stock. ASTM E112 for grain size.
• Production experience of Jiangyin Jiangnan Metal Co., Ltd. for forging windows, annealing practice, machining and inspection.

Values are given for engineering guidance and are not a warranty of the properties of any particular forging. Acceptance values are those stated on the purchase order and on the material certificate. Nimonic, Inconel, Incoloy, Hastelloy, Haynes, Waspaloy and Monel are registered marks of their respective owners and are used here only to identify the corresponding alloy composition.