Jiangyin Jiangnan Metal Co., Ltd. | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China | +86 189 2135 9659 | sales@steelforgepieces.com
Jiangyin Jiangnan Metal Co., Ltd. Open-Die Forging Factory · Jiangyin, Jiangsu, China · Since 2008
ISO 9001:2015 · EN 10204 3.1 / 3.2
Rolled rings to 3,000 mm OD · single pieces to 10 t
UNS N06690Alloy 690 · W.Nr. 2.4642 · ASTM B564 forgings
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Grade datasheet & forging capability Nickel–chromium–iron · solid solution

UNS N06690 Forgings Alloy 690 · W.Nr. 2.4642 · NiCr29Fe

Seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings and tube sheets, open-die forged to ASTM B564 / ASME SB-564.

UNS
N06690
Werkstoff
2.4642
EN name
NiCr29Fe
JIS
NCF 690
GB (China)
NS3105
Forging spec
ASTM B564

UNS N06690 is a nickel–chromium–iron alloy containing a minimum of 58% nickel, 27–31% chromium and 7–11% iron. Its chromium content is roughly double that of Alloy 600, which accounts for its resistance to primary water stress-corrosion cracking, nitric acid, nitric–hydrofluoric pickling solutions and hot caustic. It was developed as the replacement for Alloy 600 in pressurised-water reactor steam generators and is now the reference material for that duty.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges UNS N06690 to customer drawings as seamless rolled rings, flanges, bars, discs, shafts, sleeves, bushings and tube sheets, supplied solution annealed or in the 690TT thermally treated condition, ultrasonically tested and certified to EN 10204 3.1 or 3.2. Quotations: sales@steelforgepieces.com, +86 189 2135 9659.

Forged by Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin · Jiangsu · China
ASTM B564 · EN 10204 3.1 / 3.2 · ISO 9001:2015

27–31 %Chromium, roughly double the level specified for Alloy 600.
58 % minNickel. Resists chloride and caustic stress-corrosion cracking.
715 °CThermal treatment that produces the 690TT condition.
586 MPaTensile minimum for forgings under ASTM B564.

01 · Summary

UNS N06690 at a glance

Table 1. UNS N06690 (Alloy 690) key data
GradeAlloy 690 (also written Inconel® 690, Alloy 690TT when thermally treated)
UNS numberN06690
Werkstoff Nr. / EN name2.4642 / NiCr29Fe
Alloy familyNickel–chromium–iron, austenitic, solid solution, not age hardenable
Forging standardASTM B564 / ASME SB-564
Delivery conditionSolution annealed ≈1040–1100 °C, rapid cooled; optional 690TT thermal treatment
Tensile / yield / elongation, min586 MPa / 241 MPa / 30 %
Density8.19 g/cm³ (0.296 lb/in³)
Melting range1343–1377 °C (2450–2510 °F)
Key resistancePrimary water SCC, nitric acid, nitric–HF, hot caustic, high-temperature oxidation
CertificationEN 10204 3.1 or 3.2 (third-party witnessed)
Forged byJiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China

02 · Overview

What UNS N06690 is, and when to specify it

UNS N06690 belongs to the nickel–chromium–iron family, alongside Alloy 600 and Alloy 601. Where Alloy 600 is specified at 14–17% chromium, Alloy 690 carries 27–31%. Most of the difference in service behaviour between the two grades follows from that higher chromium content.

The chromium forms a dense, stable Cr₂O₃ film that resists oxidising acids, nitric acid in particular, and remains protective in high-temperature oxidising gases. The nickel content, 58% minimum, accounts for the alloy's immunity to chloride stress-corrosion cracking and its resistance to hot sodium hydroxide. Both of those environments attack austenitic stainless steels.

Few alloys cover both oxidising and reducing conditions, and alloys with good chloride resistance often perform poorly in nitric acid. Alloy 690 covers nitric acid, nitric–hydrofluoric pickling baths, caustic solutions, chlorides and high-temperature oxidation in a single material, which accounts for its use in nuclear fuel reprocessing, in glass vitrification melters for radioactive waste and in nitric acid plant hardware.

Why it replaced Alloy 600 in nuclear service

Alloy 600 was the original steam generator tubing material for pressurised-water reactors. From the 1970s onward it suffered widespread primary water stress-corrosion cracking, and steam generators were replaced at considerable cost. Alloy 690, with roughly double the chromium, does not crack under those conditions, and it became the reference material for replacement steam generators and for new-build units, in tubing, tube sheets, divider plates and the associated forged hardware.

Selection summary. For oxidising, caustic and nuclear primary water service, specify UNS N06690. For reducing conditions such as sulfuric acid, hydrochloric acid and reducing chlorides, high chromium gives no benefit, and a molybdenum-bearing alloy such as Alloy 625 or Hastelloy® C-276 is the appropriate choice.

03 · Chemistry

Chemical composition of UNS N06690

Composition limits below are those of ASTM B564 / ASME SB-564 and ASTM B166 for UNS N06690, in weight percent. The two highlighted rows are the elements that define the grade and separate it from Alloy 600.

Table 2. UNS N06690 chemical composition limits, weight %
ElementMin %Max %Role in the alloy
Nickel (Ni)58.0balanceBase element. Gives immunity to chloride SCC and resistance to hot caustic
Chromium (Cr)27.031.0Forms the Cr₂O₃ film. The defining addition of the grade: resists nitric acid, oxidising gases and primary water SCC
Iron (Fe)7.011.0Balances cost and keeps the austenite stable
Carbon (C)0.05Kept low for intergranular corrosion resistance; the residual carbon is what forms the grain-boundary carbides in the 690TT treatment
Manganese (Mn)0.50Deoxidiser; combines with sulfur
Silicon (Si)0.50Deoxidiser; assists oxidation resistance
Copper (Cu)0.50Residual limit
Sulfur (S)0.015Held low for hot workability. Nickel–sulfur eutectics cause hot shortness in forging

Table compiled by Jiangyin Jiangnan Metal Co., Ltd. from ASTM B564 and ASTM B166. Every heat is supplied with a ladle analysis on the mill certificate; product analysis on the finished forging can be added on request. Nuclear procurement specifications frequently tighten carbon, cobalt and boron beyond the ASTM limits. Send the specification with the enquiry so it can be confirmed before melting.

Cobalt limits matter in nuclear work. ASTM B564 does not restrict cobalt, but nuclear buyers usually do, commonly to 0.05% or 0.10% maximum, because Co-59 activates to Co-60 in the core. If your specification carries a cobalt limit, state it on the enquiry. It constrains which heats can be used and has to be settled before the material is melted.

04 · Mechanical

Mechanical properties of UNS N06690 forgings

Specified minimums, ASTM B564 / ASME SB-564, annealed

These are the values a mill certificate has to meet. They are minimums, not typical values, and they apply at room temperature.

Table 3. Room-temperature mechanical minimums, UNS N06690 forgings, solution annealed
PropertyMetricImperial
Tensile strength Rm, min586 MPa85 ksi
Yield strength Rp0.2, min241 MPa35 ksi
Elongation in 50 mm or 4D, min30 %30 %

Typical as-delivered values

Solution-annealed UNS N06690 forgings normally test well above the specified minimums. The ranges below are representative of our production and vary with section size, reduction ratio and cooling rate.

Table 4. Typical room-temperature properties, solution annealed forgings
PropertyTypical (metric)Typical (imperial)
Tensile strength620–760 MPa90–110 ksi
Yield strength 0.2 %250–380 MPa36–55 ksi
Elongation35–50 %35–50 %
Reduction of area55–70 %55–70 %
Hardness140–190 HB140–190 HB
Impact energy, Charpy V, 20 °C>150 J>110 ft·lb

Typical values are for design screening only. The mill test certificate issued with each forging governs acceptance. Elevated-temperature tensile, stress-rupture and impact testing are available to your specification.

The 690TT condition does not raise strength. Thermal treatment near 715 °C alters the grain-boundary carbide morphology to improve stress-corrosion cracking resistance. Room-temperature tensile and yield strength change very little and hardness is substantially unchanged. Higher mechanical properties should not be expected as a consequence of the thermal treatment.

05 · Physical

Physical properties of UNS N06690

Table 5. Nominal physical properties at room temperature unless stated
PropertyMetricImperial
Density8.19 g/cm³0.296 lb/in³
Melting range1343–1377 °C2450–2510 °F
Modulus of elasticity211 GPa30.6 × 10⁶ psi
Shear modulus81.8 GPa11.9 × 10⁶ psi
Poisson's ratio0.2890.289
Specific heat, 20 °C450 J/kg·K0.108 Btu/lb·°F
Thermal conductivity, 20 °C13.5 W/m·K94 Btu·in/ft²·h·°F
Mean expansion, 20–100 °C14.1 µm/m·K7.8 × 10⁻⁶ in/in·°F
Electrical resistivity, 20 °C1.148 µΩ·m691 Ω·circ mil/ft
Magnetic responseEssentially non-magneticEssentially non-magnetic

Properties at temperature

Thermal conductivity and specific heat both rise steadily with temperature, which is relevant when the alloy is used as a heat-transfer surface.

Table 6. UNS N06690 thermal properties versus temperature
TemperatureThermal conductivitySpecific heatMean expansion from 20 °C
20 °C13.5 W/m·K450 J/kg·K
200 °C15.4 W/m·K497 J/kg·K14.31 µm/m·K
400 °C19.1 W/m·K551 J/kg·K14.80 µm/m·K
600 °C22.9 W/m·K604 J/kg·K15.70 µm/m·K
800 °C26.6 W/m·K658 J/kg·K16.60 µm/m·K
1000 °C30.1 W/m·K711 J/kg·K17.41 µm/m·K

06 · Heat treatment

Heat treatment and the 690TT condition

UNS N06690 is a solid-solution alloy. It is not precipitation hardened, and no ageing treatment is applied. The standard delivery condition for forgings is solution annealed and rapidly cooled. A separate low-temperature thermal treatment is added only when the specification calls for the 690TT condition.

Table 7. Heat treatment cycles for UNS N06690 forgings
CycleTemperatureHoldCoolingPurpose
Hot working1040–1230 °CAirHeavy forging range. Light finishing work down to about 870 °C
Solution anneal1040–1100 °C≈1 h per 25 mmWater or forced airDissolves carbides, recrystallises the structure, restores ductility
Thermal treatment (690TT)700–730 °C10–16 hAirPrecipitates semi-continuous chromium carbides on grain boundaries for maximum SCC resistance
Stress relief after machiningNot standardOnly where the design code or drawing requires it — discuss before ordering

Cycles above are our normal practice. Nuclear and code work is always performed to the customer's written procedure, and furnace charts are supplied with the certificate.

Solution annealed or 690TT: which to order

Solution annealed material, sometimes written 690SA, covers the large majority of chemical process work, including nitric acid service, pickling equipment, heat exchanger components and general oxidising duty. It costs less, the lead time is shorter, and corrosion performance in those environments is already excellent.

The 690TT condition is specified where stress-corrosion cracking is the governing failure mode, principally nuclear primary circuit hardware, caustic evaporator service and replacements for Alloy 600 components that have cracked in service. The extended hold near 715 °C precipitates chromium carbides onto the grain boundaries in a semi-continuous form, and that morphology restricts intergranular crack propagation.

A note on delivery condition wording. UNS N06690 is sometimes described as supplied “solution treated and aged”. That description is incorrect. The alloy contains no aluminium or titanium in hardening quantities and forms no gamma-prime, so there is no ageing response. An order written that way may be filled with either plain annealed material or 690TT material, depending on the supplier's interpretation. State the required condition on the purchase order as solution annealed per ASTM B564 or solution annealed + thermal treatment 715 °C / 15 h (690TT).

07 · Selection

Alloy 690 compared with 600, 625 and 800H

These four grades cover overlapping duties and are frequently confused on drawings and purchase orders. The table below sets out how they differ.

Table 8. UNS N06690 compared with neighbouring nickel alloys
Criterion Alloy 690 Alloy 600 Alloy 625 Alloy 800H
UNSN06690N06600N06625N08810
Chromium %27–3114–1720–2319–23
Nickel %58 min72 min58 min30–35
Molybdenum %nonenone8–10none
StrengtheningSolid solutionSolid solutionSolid solution + NbSolid solution
Nitric acidExcellentPoorFairFair
Reducing acids (H₂SO₄, HCl)PoorFairExcellentPoor
Primary water SCCResistantSusceptibleResistantNot used
Hot causticExcellentGoodGoodFair
Creep service >600 °CModerateModerateGoodExcellent
Relative costHighMediumVery highLow
Choose it whenOxidising acids, caustic, nuclear primary waterLegacy service, dry chlorine, food and caustic at lower costReducing acids, seawater, pitting resistance, high strengthSustained load at red heat where creep governs

Chromium governs performance in oxidising environments and molybdenum governs performance in reducing ones. Alloy 690 is the highest-chromium, molybdenum-free grade in this group. It performs well in nitric acid and nuclear primary water, and poorly in sulfuric and hydrochloric acid.

08 · Designations

UNS N06690 equivalent designations

Table 9. International designations for Alloy 690
SystemDesignation
UNS (USA)N06690
Werkstoff Nr. (Germany)2.4642
EN / DIN nameNiCr29Fe
JIS (Japan)NCF 690
GB (China)NS3105 · NS315 · 0Cr30Ni60Fe10
AWS filler metalERNiCrFe-7 · ERNiCrFe-7A · ENiCrFe-7
Trade namesInconel® 690, Nicrofer® 6030, Sanicro® 690, VDM® Alloy 690, Haynes® 690, Allvac 700

Trademark notice. Inconel® is a registered trademark of Special Metals Corporation, Nicrofer® of VDM Metals, Sanicro® of Sandvik and Haynes® of Haynes International. Material made by those companies and sold under those brands is theirs. Material we produce is correctly described as UNS N06690 / Alloy 690 / W.Nr. 2.4642 / ASTM B564, the same generic specification, manufactured independently by Jiangyin Jiangnan Metal Co., Ltd. We are not affiliated with, sponsored by or endorsed by any of the trademark holders named above, and the marks are used here solely to identify the equivalent material specification.

09 · Standards

Standards covering UNS N06690 by product form

Table 10. ASTM and ASME specifications for UNS N06690
Product formASTMASME
Forgings (our core product)B564SB-564
Rod, bar and wireB166SB-166
Seamless pipe and tubeB167SB-167
Condenser and heat exchanger tubeB163SB-163
Plate, sheet and stripB168SB-168
FittingsB366SB-366
Welded pipeB517SB-517
Welded tubeB516SB-516

Order forgings to ASTM B564 or ASME SB-564 and state the UNS number. Where the part is a pressure boundary in a coded vessel, name the code edition on the enquiry so the correct certificate wording and third-party involvement can be arranged before production starts.

10 · Product forms

UNS N06690 forgings we produce

Every item below is forged to the customer's drawing or dimensional sketch. Open-die work needs no dies, so there is no tooling charge, no minimum piece quantity, and one-off and prototype orders are economic.

Open-die forged product forms produced in UNS N06690 Line drawings of a seamless rolled ring, a forged flange, a round bar, a disc, a stepped shaft and a drilled tube sheet, all produced in Alloy 690. ROLLED RINGseamless, no weld FLANGEWN / SO / blind ROUND BARforged & peeled DISCupset forged STEPPED SHAFTmulti-diameter TUBE SHEETdrilled or blank
Open-die forged product forms produced in UNS N06690 (Alloy 690) by Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China.
Seamless rolled ringsRing-rolled with no weld seam. Rectangular or profiled section.
Forged flangesWN, SO, blind, long weld neck and orifice, to ASME B16.5 / B16.47 or drawing.
Round bars and billetsForged and peeled or rough turned, cut to length.
Discs and blanksUpset forged discs for covers, blind ends and tube sheet blanks.
Shafts and spindlesStraight, stepped and eccentric shafts; pump and agitator shafts.
Sleeves and bushingsHollow forged, trepanned or bored, thin or heavy wall.
Tube sheetsForged and drilled tube sheets for shell-and-tube exchangers.
Hollow bars and forged pipeTrepanned or expanded hollows for heavy-wall pipe sections.
Valve componentsBodies, bonnets, seat rings, stems, gate and plug blanks.
Nozzles and manifoldsForged nozzle bodies, headers, blocks and custom shapes.

Size and weight capability in UNS N06690

Table 11. UNS N06690 open-die forging capability
Product formDimensional rangeUnit weight
Seamless rolled ringsOD 200–3,000 mm, height to 800 mm20–8,000 kg
Round barsØ80–800 mm, length to 6,000 mm20–6,000 kg
Discs and tube sheetsØ200–2,500 mm, thickness to 600 mm30–10,000 kg
Shafts, sleeves, blocksto 6,000 mm longto 10,000 kg

Machining allowance is normally 6–20 mm per surface depending on section size, unless your drawing states otherwise. Finish-machined parts to print are also supplied. Use the forging weight calculator below to estimate the input weight for your part.

11 · Manufacturing

How we make UNS N06690 forgings

  1. MeltingUNS N06690 stock is produced by vacuum induction melting followed by electroslag remelting (VIM + ESR), with VAR available where the specification calls for the lowest inclusion content. Remelting is more significant for this grade than for steel, because nickel alloys segregate readily and forge poorly when the ingot structure is coarse.
  2. Chemistry verificationHeat chemistry is checked by spectrometer against ASTM B564 limits before any material is heated, including any customer-imposed cobalt, boron or nitrogen restriction.
  3. Open-die forgingForged on hydraulic presses in the 1040–1230 °C range with controlled reduction to close porosity and develop grain flow that follows the part contour. Alloy 690 has a narrower hot-working window than carbon or stainless steel and needs more reheats, so forging is planned pass by pass.
  4. Seamless ring rollingRings are pierced and rolled on a radial–axial ring mill, producing a circumferential grain flow with no weld seam.
  5. Solution annealingHeld at 1040–1100 °C, roughly one hour per 25 mm of section, then rapidly cooled. Furnace charts are recorded and supplied.
  6. Thermal treatment, if 690TT is orderedA separate cycle of 10–16 hours at 700–730 °C, air cooled, performed to the customer's written procedure.
  7. Rough or finish machiningTurned, bored, drilled and faced to your drawing, with agreed machining allowance or to final dimensions.
  8. Non-destructive testingUltrasonic examination to EN 10228-3, SEP 1921, ASTM A388 or your nominated class, plus liquid penetrant and dimensional inspection as required.
  9. Certification and despatchEN 10204 3.1 mill certificate as standard, 3.2 with third-party witness on request. Hard stamped, marked, preserved and packed for sea or air freight.

12 · Applications

Where UNS N06690 forgings are used

Table 12. Typical applications for Alloy 690 forgings by industry
IndustryComponents forged in UNS N06690Why this grade
Nuclear power Steam generator tube sheets, divider plates, channel head and nozzle forgings, control rod drive housings, primary circuit valve bodies and seat rings Immunity to primary water stress-corrosion cracking that ended the service life of Alloy 600 components
Nuclear fuel reprocessing Dissolver vessel forgings, evaporator components, glass vitrification melter hardware, forged nozzles and flanges Resistance to boiling nitric acid and to nitric–hydrofluoric mixtures
Nitric acid production Tail-gas reheater forgings, absorber tower internals, heat exchanger tube sheets, valve bodies 27–31% chromium gives among the best nitric acid performance of any wrought nickel alloy
Chemical processing Caustic evaporator forgings, pickling line hardware, agitator and pump shafts, sleeves and bushings High nickel resists hot sodium hydroxide and chloride SCC; high chromium resists the oxidiser
Waste incineration and gasification Forged burner and duct components, grate hardware, nozzle blocks Oxidation and sulfidation resistance in aggressive combustion gases
Heat treatment and furnaces Retort end rings, muffle components, radiant tube forgings, fixture hardware Stable oxide film and dimensional stability under thermal cycling
Glass and mineral processing Melter electrode holders, forged rings and flanges for hot gas ducting Resistance to high-temperature oxidising atmospheres

13 · Fabrication

Welding and machining UNS N06690

Welding

UNS N06690 is readily welded by GTAW, GMAW, SMAW and SAW. The matching fillers were developed alongside the base metal for nuclear construction. A lower-chromium filler removes the corrosion advantage the base metal was selected for.

Table 13. Filler metals for UNS N06690
AWS classificationUNSCommon nameUse
ERNiCrFe-7N06052Alloy 52Bare wire for GTAW and GMAW; the standard match for Alloy 690
ERNiCrFe-7AN06054Alloy 52MNiobium-modified; better resistance to ductility-dip and hot cracking in heavy multi-pass welds
ENiCrFe-7W86152Alloy 152Covered electrode for SMAW
  • Keep interpass temperature at or below about 150 °C and heat input low.
  • Alloy 690 weld metal is susceptible to ductility-dip cracking in thick multi-pass joints. Use ERNiCrFe-7A rather than ERNiCrFe-7 on heavy joints and avoid excessive restraint.
  • Clean the joint thoroughly. Sulfur, lead, zinc and copper contamination cause hot cracking in nickel alloys.
  • Post-weld heat treatment is not required for the alloy itself, though the design code may call for it.
  • Alloy 690 filler is also widely used to clad low-alloy steel for oxidising-acid service and for dissimilar-metal nuclear joints.

Machining

The alloy work hardens rapidly and has low thermal conductivity, so heat concentrates at the cutting edge. The starting values below are for solution-annealed material with carbide tooling and should be tuned to your machine and setup.

Table 14. Starting machining parameters, solution annealed UNS N06690, carbide tooling
OperationCutting speedFeedNotes
Rough turning15–25 m/min0.25–0.40 mm/revDepth of cut 2–5 mm. Stay below the previously work-hardened layer
Finish turning25–40 m/min0.10–0.20 mm/revSharp positive-rake inserts, honed edge
Drilling8–15 m/min0.05–0.15 mm/revPeck drill, flood coolant, do not dwell
Face milling15–30 m/min0.10–0.20 mm/toothClimb mill; keep the cutter fully engaged
  • Use a rigid setup, minimum tool overhang and sharp tools throughout. A rubbing tool glazes the surface, and the following pass then has to cut through the hardened layer.
  • Maintain a positive, uninterrupted feed. Dwelling in the cut work hardens the surface and shortens tool life sharply.
  • Apply flood coolant generously. Chlorinated cutting oils must be removed completely before heat treatment or service.

14 · Quality

Testing, inspection and certification

  • Chemical analysis. Spectrometric heat analysis as standard; product analysis on the finished forging on request.
  • Mechanical testing. Room-temperature tensile, yield and elongation per ASTM B564. Elevated-temperature tensile, stress-rupture and Charpy impact testing to your specification.
  • Hardness. Brinell to ASTM E10, on the positions your drawing nominates.
  • Grain size. Determined per ASTM E112 where the specification requires it.
  • Intergranular corrosion. ASTM A262 or ASTM G28 practice as agreed, commonly specified for nitric acid and nuclear service.
  • Ultrasonic testing. EN 10228-3, SEP 1921 Class C / D / E, ASTM A388 or your nominated class.
  • Surface NDT. Liquid penetrant examination per ASTM E165 / ASME Section V Article 6.
  • PMI. Positive material identification on the finished part where required.
  • Certification. EN 10204 3.1 as standard; EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. Full heat traceability and hard stamping.

Ultrasonic examination of nickel alloys differs from ultrasonic examination of steel. The coarse, anisotropic grain structure scatters sound and raises the noise floor, so acceptance classes written for forged steel do not transfer directly. Please state the UT class and acceptance criteria at enquiry stage, so that achievability in the required section thickness can be confirmed before quotation.

15 · Tools

UNS N06690 engineering tools

Six calculators for Alloy 690. They run entirely in the browser; no data is uploaded or stored.

Forging weight calculator, Alloy 690, ρ = 8.19 g/cm³

Finished weight is the part at your drawing dimensions. Forged blank weight adds the machining allowance to every surface. Input billet weight is typically a further 15–30% higher once cut-off, test pieces and scale loss are included. That figure is confirmed with the quotation.

16 · Questions

Frequently asked questions about UNS N06690

What is UNS N06690?

UNS N06690 is a nickel–chromium–iron alloy containing a minimum of 58% nickel, 27–31% chromium and 7–11% iron, also known as Alloy 690, Werkstoff 2.4642, NiCr29Fe and NCF 690. Its high chromium content gives outstanding resistance to oxidising acids, hot caustic and stress-corrosion cracking, and it is the standard material for pressurised-water reactor steam generator tubing. Forgings are supplied to ASTM B564 / ASME SB-564.

Is UNS N06690 the same as Inconel 690?

Yes, they are the same alloy. Inconel® is a registered trademark of Special Metals Corporation; UNS N06690 is the generic designation used when the material is produced by another manufacturer. Order to UNS N06690 and ASTM B564 so the requirement is unambiguous, and the mill certificate will state the same chemistry.

What is the difference between Alloy 690 and Alloy 600?

Chromium content. Alloy 600 (UNS N06600) contains 14–17% chromium; Alloy 690 (UNS N06690) contains 27–31%. Alloy 690 was developed specifically to replace Alloy 600 in pressurised-water reactor steam generators after Alloy 600 suffered widespread primary water stress-corrosion cracking. The higher chromium also improves resistance to nitric acid, nitric–hydrofluoric pickling solutions and high-temperature oxidation.

What is 690TT and when should it be specified?

690TT means thermally treated Alloy 690: after solution annealing, the material is held at approximately 700–730 °C for 10 to 16 hours. This precipitates semi-continuous chromium carbides on the grain boundaries and substantially improves resistance to stress-corrosion cracking. Specify 690TT for nuclear primary-circuit and caustic service; solution-annealed 690 is sufficient for most chemical process duties.

Which heat treatment is correct for UNS N06690 forgings?

Solution annealing at approximately 1040–1100 °C followed by rapid cooling. UNS N06690 is a solid-solution alloy and is not precipitation hardened, so no ageing treatment is applied. Where the specification calls for it, a separate thermal treatment near 715 °C is added to produce the 690TT condition for improved stress-corrosion cracking resistance.

Which standards cover UNS N06690 forgings?

Forgings are covered by ASTM B564 and ASME SB-564. Related product forms are covered by ASTM B166 (rod, bar and wire), ASTM B167 (seamless pipe and tube), ASTM B168 (plate, sheet and strip), ASTM B163 (condenser and heat exchanger tube) and ASTM B366 (fittings). Certification is normally to EN 10204 3.1 or 3.2.

Can UNS N06690 be welded, and with which filler metal?

Yes. UNS N06690 is readily welded by GTAW, GMAW and SMAW. The matching fillers are ERNiCrFe-7 and the niobium-modified ERNiCrFe-7A for wire, and ENiCrFe-7 for covered electrodes. Keep interpass temperature at or below about 150 °C and heat input low, because the alloy is susceptible to ductility-dip cracking in heavy multi-pass welds. Post-weld heat treatment is not required for the alloy itself unless the design code calls for it.

What sizes of UNS N06690 forgings can you supply?

Seamless rolled rings from 200 to 3,000 mm outside diameter, round bars from 80 to 800 mm diameter and up to 6,000 mm long, discs and tube sheets from 200 to 2,500 mm diameter, and shafts, sleeves and blocks up to 6,000 mm long, with single-piece weights up to about 10,000 kg. Open-die forging needs no dies, so one-off and prototype quantities are economic and there is no tooling charge.

Do you supply a material certificate with UNS N06690 forgings?

Every forging ships with an EN 10204 3.1 mill test certificate as standard, showing heat number, chemical analysis, mechanical test results, heat treatment record and non-destructive testing results. EN 10204 3.2 certification witnessed by a third party such as TÜV, BV, LR, SGS or DNV is available on request at the time of order.

Who supplies open-die forged UNS N06690 in China?

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges UNS N06690 and other nickel alloys, stainless steels, tool steels, alloy steels and carbon steels into seamless rolled rings, flanges, bars, discs, shafts, sleeves and tube sheets, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.

17 · Enquiry

Request a quotation for UNS N06690 forgings

Send a drawing, a sketch, or just the dimensions and quantity. We quote open-die forgings in Alloy 690 with no tooling charge and no piece minimum.

Useful details if you have them: grade and standard (UNS N06690 / ASTM B564), product form, dimensions with machining allowance, quantity, delivery condition (690SA or 690TT), any cobalt restriction, UT class, certificate type and required delivery date. The RFQ writer above assembles these into a single enquiry.

Company
Jiangyin Jiangnan Metal Co., Ltd.
Business
Open-die forging factory
Address
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone / WhatsApp
+86 189 2135 9659

Email your drawing for a quote

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