UMCO 51 Forgings: UMCo-51 Cobalt-Base Superalloy Rings, Bars, Flanges and Shafts

Q: What is the chemical composition of UMCO 51?

UMCo-51 contains nominally 28% chromium, about 20% iron, up to 3% nickel and roughly 0.30% carbon, with cobalt as the balance at about 48 to 50%. Silicon and manganese are each held to 1.0% maximum. The high carbon level is what separates UMCo-51 from UMCo-50 and is the source of its higher creep and abrasion resistance.

Q: What is the difference between UMCo-50 and UMCo-51?

Both are cobalt-base alloys with about 28% chromium. UMCo-50 is a low-carbon grade at 0.12% maximum, set up for thermal-shock resistance. UMCo-51 carries roughly 0.30% carbon and is set up for stress-rupture strength and abrasion resistance. UMCo-50 holds the material number 2.4778 and the casting designation G-CoCr28; UMCo-51 does not. Choose UMCo-50 for thermally cycled parts under light load, and UMCo-51 for parts loaded at temperature.

Q: What is the maximum service temperature of UMCO 51?

UMCo-51 is generally applied up to about 1150 C (2100 F) in continuous oxidising service, with short excursions to roughly 1350 C (2460 F). Its usable limit is higher than that of nickel-base heat-resistant alloys with comparable chromium content, because the cobalt matrix has a higher melting point. The real limit for a given part depends on load, atmosphere and cycle frequency.

Jiangyin Jiangnan Metal Co., Ltd. forges UMCo-51 cobalt-base heat-resistant alloy to customer drawings. Seamless rolled rings, round bars, flanges, discs, shafts, sleeves and tube sheets, supplied with EN 10204 3.1 or 3.2 material certification.

UMCo-51 supplier data sheet, Jiangyin Jiangnan Metal Co., Ltd.

Alloy base: Cobalt
Nominal Cr: 28 %
Density: 8.3 g/cm³
Max service: 1150 °C
Ring OD: 80–6000 mm
Max length: 12 000 mm
Max piece: 15 000 kg
Certification: EN 10204 3.1

Overview

UMCO 51 (UMCo-51) is a cobalt-base heat-resistant superalloy. It runs about 28 % chromium with cobalt as the balance. Carbon sits near 0.30 %, higher than in UMCo-50, and this is what gives the alloy its stress-rupture strength. It is specified for parts that carry load above 1000 °C while also facing abrasion, thermal shock and oxidation. Furnace components, heat-treatment fixtures and hot-gas hardware are the usual applications.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works in Jiangyin, Jiangsu Province, China. The plant forges UMCo-51 rings, bars, flanges, shafts and discs to customer drawing, on a 4500 ton hydraulic press and 3 m and 6 m ring rolling mills. Forgings are ultrasonically tested to EN 10228-3 and certified to EN 10204 3.1 or 3.2. For a quotation, email sales@steelforgepieces.com or call 0086-189-2135-9659.

What is UMCO 51 alloy?

UMCo-51 is a cobalt-chromium heat-resistant alloy listed by ASM International as Alloy Digest filing code Co-51. The original producer was Aciéries et Fonderies de Haute Sambre. The alloy has high stress-rupture strength and is specified for high-temperature work where mechanical stresses are high and where resistance to abrasion, thermal shock and oxidation are all required.

UMCo-51 belongs to the same family as UMCo-50 (W.-Nr. 2.4778, G-CoCr28, SAE J467). The difference is carbon. UMCo-51 runs at roughly 0.30 % carbon against a 0.12 % maximum for UMCo-50. That extra carbon forms chromium-rich carbides, which raise creep and rupture strength and improve abrasion resistance. Ductility and weldability drop as a result. For a part that deforms under load at temperature, UMCo-51 is normally the better choice. For a part that cracks from thermal cycling, UMCo-50 usually lasts longer.

Grade designation

The material number 2.4778 and the casting designation G-CoCr28 belong to UMCo-50, not to UMCo-51. Traders often cross-list the two grades as if they were interchangeable. Jiangyin Jiangnan Metal Co., Ltd. asks customers to state which grade is required on the enquiry, because the carbon specification and the mechanical properties that follow from it are different.

UMCO 51 chemical composition

Table 1. UMCo-51 nominal chemical composition in weight per cent, as supplied by Jiangyin Jiangnan Metal Co., Ltd. Heat-specific analysis is reported on the EN 10204 3.1 certificate issued with each order.
Element	Min %	Max %	Typical %	Function in the alloy
CCarbon	0.20	0.40	0.30	Forms M₂₃C₆ carbides. Main source of creep strength
CrChromium	26.0	30.0	28.0	Builds the Cr₂O₃ scale that resists oxidation and sulphidation
SiSilicon	—	1.00	0.80	Deoxidiser. Helps the oxide scale stay attached
MnManganese	—	1.00	0.80	Deoxidiser and sulphur control
NiNickel	—	3.00	1.50	Stabilises austenite and improves hot workability
FeIron	18.0	22.0	20.0	Reduces alloy cost without giving up high-temperature capability
PPhosphorus	—	0.030	≤0.020	Residual. Held down to limit grain-boundary embrittlement
SSulphur	—	0.030	≤0.015	Residual. Held down for hot ductility
CoCobalt	Balance, about 48–50			Matrix. High melting point and good thermal-fatigue resistance

Ranges above are nominal values for enquiry purposes. Where a purchase order cites a customer or national specification, Jiangyin Jiangnan Metal Co., Ltd. melts and certifies to that specification.

UMCO 51 mechanical and physical properties

Table 2. Typical room-temperature properties of UMCo-51 forgings in the solution-annealed condition, Jiangyin Jiangnan Metal Co., Ltd.
Property	Metric	Imperial	Test method
Tensile strength, R_m	640–780 MPa	93–113 ksi	ASTM E8 / ISO 6892-1
Yield strength, R_p0.2	330–420 MPa	48–61 ksi	ASTM E8 / ISO 6892-1
Elongation, A₅	8–18 %	8–18 %	ASTM E8
Hardness	180–240 HB	89–100 HRB	ASTM E10
Density	8.3 g/cm³	0.300 lb/in³	ASTM B311
Melting range	1350–1430 °C	2460–2606 °F	—
Maximum continuous service temperature	≈1150 °C	≈2100 °F	Oxidising atmosphere
Maximum intermittent service temperature	≈1350 °C	≈2460 °F	Short cycle, oxidising
Coefficient of thermal expansion, 20–1000 °C	≈16.5 µm/m·K	≈9.2 µin/in·°F	ASTM E228

These values are indicative and are meant for design screening. They are not a guarantee of supply. Section size, forging reduction and heat-treatment condition all move the numbers. Acceptance values are agreed at order stage and reported per heat.

UMCo-51 or UMCo-50: which grade do you need?

Table 3. The two UMCo heat-resistant cobalt grades forged by Jiangyin Jiangnan Metal Co., Ltd.
Criterion	UMCo-50	UMCo-51
Material number	2.4778 (G-CoCr28)	No W.-Nr. assigned
Reference	SAE J467, ASM Alloy Digest Co-41	ASM Alloy Digest Co-51
Nominal carbon	≤ 0.12 %	≈ 0.30 %
Nominal chromium	28 %	28 %
Main strength	Thermal-shock resistance	Stress-rupture and creep strength
Abrasion resistance	Good	Higher, carbide strengthened
Ductility and weldability	Higher	Lower
Typical use	Skid rails, quench trays, sintering bars, glass-plant hardware	Loaded furnace components, hot-gas parts, wear parts under load at temperature

A part that is thermally cycled but lightly loaded normally lasts longer in UMCo-50. A part that carries load at temperature, or that sees abrasive contact, is the case for UMCo-51. Jiangyin Jiangnan Metal Co., Ltd. forges both grades and can quote them side by side on the same drawing. See UMCO 50 forgings.

UMCO 51 forged products and size range

Table 4. UMCo-51 forged product forms and size range, Jiangyin Jiangnan Metal Co., Ltd.
Product form	Size range	Supply condition
Seamless rolled rings	OD 80–6000 mm	As-forged or rough-machined
Forged round bars	Ø 100–1200 mm, L ≤ 12 000 mm	+5/−0 mm as-forged, h9 machined
Forged flanges	OD ≤ 2500 mm	ASME B16.5 / B16.47 or to drawing
Forged discs and blanks	Ø 200–2500 mm	Rough-machined
Forged shafts	Ø 100–1000 mm, L ≤ 12 000 mm	Machining allowance to drawing
Forged sleeves and bushings	OD ≤ 1500 mm	Bored and rough-turned
Hollow bars and forged tubes	OD ≤ 1200 mm	Trepanned or bored
Forged tube sheets	Ø ≤ 2500 mm	Flat, rough-machined
Forged blocks	Thickness ≤ 800 mm	Six faces machined on request

Works envelope: diameter 100 mm to 6000 mm, length 100 mm to 12 000 mm, single-piece mass 10 kg to 15 000 kg. Sizes outside this envelope are quoted case by case.

Works and equipment

Jiangyin Jiangnan Metal Co., Ltd. employs 460 staff, including 9 senior engineers and 32 engineers. Melting, forging, heat treatment, machining and testing are all carried out in-house.

4500 ton hydraulic open-die forging press
1, 3, 6 and 9 ton forging hammers
3 m and 6 m seamless ring rolling mills
Heat-treatment furnaces with recorded and calibrated cycles
Machining shop for rough and finish machining to drawing
Chemical, mechanical, ultrasonic and metallographic test facilities

How UMCO 51 forgings are made

Melting

UMCo-51 stock is vacuum induction melted and electroslag remelted (VIM + ESR). Where the specification calls for it, the material is triple melted VIM + ESR + VAR. Remelted stock is recommended for rings and shafts that will be ultrasonically tested to a tight acceptance class.

Forging and ring rolling

Ingots are upset and drawn on the hydraulic open-die press to a minimum forging reduction ratio of 3:1. This breaks down the as-cast structure and closes internal porosity. Ring blanks are pierced and expanded on the ring rolling mills, which gives seamless rolled rings a continuous circumferential grain flow.

Heat treatment

Forgings are solution annealed and rapidly cooled to dissolve grain-boundary carbide networks and restore ductility. Temperature and soak time are set against the governing specification and the section thickness, then recorded on the certificate.

Machining

Parts are supplied as-forged, rough-machined with an agreed allowance, or finish-machined to drawing. UMCo-51 work-hardens quickly. Low cutting speeds, positive rake carbide tooling, rigid setups and heavy uninterrupted cuts give the best tool life.

Testing, inspection and certification

Chemical analysis. Spectrographic analysis on each heat, reported element by element.
Mechanical testing. Tensile and hardness testing to ASTM E8 and ASTM E10. Impact and elevated-temperature testing on request.
Ultrasonic testing. To EN 10228-3, SEP 1921, ASTM A388 or ASTM A745, at the acceptance class stated on the order.
Surface examination. Liquid penetrant testing to ASTM E165 where specified.
Dimensional inspection. Recorded against the customer drawing.
Material certification. EN 10204 type 3.1 as standard. Type 3.2 with third-party witness from SGS, BV, TÜV or Lloyd's Register on request.
Metallography. Grain size, microstructure and intergranular corrosion testing where the application requires it.

Applications for UMCO 51 forgings

Industrial furnaces

Hearth rolls, skid rails, walking-beam parts, radiant tube supports, burner hardware and furnace rolls running continuously above 1000 °C.

Heat-treatment equipment

Quench trays, baskets, fixtures, grids and charge carriers that see repeated heating and quenching cycles.

Gas turbine and thermal processing

Rolled rings, casings and shaft components for gas turbine engineering and industrial thermal processing plant.

Non-ferrous metallurgy

Sintering bars, tooling and handling hardware exposed to hot slag, sulphur and vanadium bearing gases, and molten copper.

Glass manufacturing

Moulds, plungers, rolls and support hardware in contact with molten glass under cyclic thermal load.

Cement, waste-to-energy, petrochemical

Grate bars, kiln nose-ring segments, hot-gas ducting hardware and reformer parts in abrasive high-temperature service.

Frequently asked questions about UMCO 51

What is UMCO 51 alloy used for?

UMCo-51 is used for parts that carry mechanical load while exposed to temperatures above 1000 °C and to abrasion, thermal shock, or oxidising and sulphidising gases. Common parts are furnace hearth rolls and skid rails, heat-treatment fixtures and quench trays, sintering bars in copper metallurgy, glass-plant tooling, and rolled rings and shafts for gas turbine and thermal processing equipment.

What is the chemical composition of UMCO 51?

UMCo-51 contains nominally 28 % chromium, about 20 % iron, up to 3 % nickel and roughly 0.30 % carbon, with cobalt as the balance at about 48 to 50 %. Silicon and manganese are each held to 1.0 % maximum. The high carbon level is what separates UMCo-51 from UMCo-50 and is the source of its higher creep and abrasion resistance. Full ranges are given in Table 1 on this page.

What is the difference between UMCo-50 and UMCo-51?

Both are cobalt-base alloys with about 28 % chromium. UMCo-50 is a low-carbon grade at 0.12 % maximum, set up for thermal-shock resistance. UMCo-51 carries roughly 0.30 % carbon and is set up for stress-rupture strength and abrasion resistance. UMCo-50 holds the material number 2.4778 and the casting designation G-CoCr28; UMCo-51 does not. Choose UMCo-50 for thermally cycled parts under light load, and UMCo-51 for parts loaded at temperature.

What is the maximum service temperature of UMCO 51?

UMCo-51 is generally applied up to about 1150 °C (2100 °F) in continuous oxidising service, with short excursions to roughly 1350 °C (2460 °F). Its usable limit is higher than that of nickel-base heat-resistant alloys with comparable chromium content, because the cobalt matrix has a higher melting point. The real limit for a given part depends on load, atmosphere and cycle frequency.

Can UMCO 51 be welded and machined?

UMCo-51 can be welded by arc processes, but the higher carbon content makes it more crack-sensitive than UMCo-50. Use preheat, control the interpass temperature, and select a matching or cobalt-base filler. Post-weld solution annealing is preferred for loaded joints. For machining, the alloy work-hardens fast. Use positive-rake carbide tooling, low surface speed, heavy feed, rigid fixturing and generous coolant, and do not let the tool dwell in the cut.

Which UMCO 51 forged shapes can Jiangyin Jiangnan Metal supply?

Jiangyin Jiangnan Metal Co., Ltd. supplies UMCo-51 as seamless rolled rings with outside diameter from 80 to 6000 mm, forged round bars from 100 to 1200 mm diameter, flanges, discs and blanks, shafts, sleeves and bushings, hollow bars and forged tubes, tube sheets and forged blocks. Length runs to 12 000 mm and single-piece mass to 15 000 kg. All shapes are forged to customer drawing or to a dimensional standard named on the order.

What certification is supplied with UMCO 51 forgings?

Every order ships with an EN 10204 type 3.1 material certificate giving heat number, chemical analysis, mechanical test results, heat-treatment record and NDT results. EN 10204 type 3.2 certification witnessed by SGS, BV, TÜV or Lloyd's Register is available on request. Ultrasonic testing is carried out to EN 10228-3, SEP 1921, ASTM A388 or ASTM A745 as specified.

Who supplies UMCO 51 forgings?

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works in Jiangyin, Jiangsu Province, China that manufactures UMCo-51 cobalt-base superalloy forgings: rolled rings, bars, flanges, shafts, discs and tube sheets, made to customer drawing, with EN 10204 3.1 or 3.2 certification and export supply worldwide. The works is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Enquiries go to sales@steelforgepieces.com or 0086-189-2135-9659.

What is the minimum order quantity and lead time for UMCO 51?

There is no fixed minimum order quantity. Single prototype pieces are accepted, and single-piece orders are common for furnace spares. Lead time runs about 25 to 45 days for forgings made from stock material, and 45 to 70 days where a dedicated heat has to be melted, counted from drawing approval. Confirmed dates are issued with the order acknowledgement.

How much do UMCO 51 forgings cost?

UMCo-51 is priced per kilogram and follows the cobalt and chromium markets, so quotations are issued against a current-day metal price and normally hold for 15 to 30 days. Price depends on finished weight, input weight after machining allowance, melting route, testing scope and certification level. Send a drawing, or the dimensions and quantity, to sales@steelforgepieces.com for a firm quotation.

Request a quotation for UMCO 51 forgings

Send a drawing, or the outside diameter, wall or thickness, length and quantity. Jiangyin Jiangnan Metal Co., Ltd. answers UMCo-51 enquiries within one working day with price, forged weight, lead time, and the testing and certification scope.

Company: Jiangyin Jiangnan Metal Co., Ltd.
Open-die forging works
Works address: No.1 Chengxiqiao Road, Zhouzhuang Town,
Jiangyin City, Jiangsu Province, China
Telephone, WhatsApp, WeChat: 0086-189-2135-9659
Email: sales@steelforgepieces.com

Email an enquiry Call 0086-189-2135-9659

References

ASM International, Alloy Digest Co-51, UMCo-51 High-Temperature Alloy. ASM International, Alloy Digest Co-41, UMCo-50 Cobalt-Base Heat Resistant Alloy. SAE J467, Special Purpose Alloys. EN 10204, Metallic products, types of inspection documents. EN 10228-3, Non-destructive testing of steel forgings, ultrasonic testing.

Maintained by the technical sales department of Jiangyin Jiangnan Metal Co., Ltd. Last reviewed 29 August 2026.