Modern Methods of Ferritic Nitrocarburizing (FNC) Open bed at temperature Loaded basket, ready for carousel Removal from fluidized quench 28 dia 48 depth.

Modern Methods of Ferritic Modern Methods of Ferritic Nitrocarburizing (FNC)Nitrocarburizing (FNC)

Open bed at temperature

Loaded basket, ready for carousel

Removal from fluidized quench

28” dia 48” depth

open basket

H-13 section

Ferritic Nitrocarburizing (FNC)Ferritic Nitrocarburizing (FNC)How we got hereHow we got here

1900’s – Dr. Adolph Fry1900’s – Dr. Adolph Fry Discovered that Nitrogen and Iron had affinity to Discovered that Nitrogen and Iron had affinity to

one another.one another. Developed nitrogen iron equilibrium tableDeveloped nitrogen iron equilibrium table Nitralloy steelsNitralloy steels Studied effect of adding other alloys Vanadium, Studied effect of adding other alloys Vanadium,

Tungsten, Manganese, Molybdenum, TitaniumTungsten, Manganese, Molybdenum, Titanium

Ferritic Nitrocarburizing (FNC)Ferritic Nitrocarburizing (FNC)Continued 2Continued 2

1900’s Adolph Machlet – New Jersey1900’s Adolph Machlet – New Jersey American Gas Company - ElizabethAmerican Gas Company - Elizabeth Applied for patents which were received Applied for patents which were received

June 24, 1913June 24, 1913 US saw no commercial benefit at the timeUS saw no commercial benefit at the time

1927 Pierre Aubert – Chicago1927 Pierre Aubert – Chicago At SME convention presented research for At SME convention presented research for

practical applications in Europepractical applications in Europe Included railway steel, machine tools, Included railway steel, machine tools,

auto, aviation.auto, aviation. Benefits – hard surface, core not changed, Benefits – hard surface, core not changed,

high wear, unaffected by temper, high wear, unaffected by temper, corrosion resistance.corrosion resistance.

Ferritic Nitrocarburizing (FNC)Ferritic Nitrocarburizing (FNC)Continued 3Continued 3

1928 – McQuaid and Ketchum1928 – McQuaid and Ketchum Timken – Detroit Axle Co.Timken – Detroit Axle Co. Metallurgists – practical applicationsMetallurgists – practical applications Used work of Fry and Machlet as pivot pointUsed work of Fry and Machlet as pivot point

1929 – Robert Sergeson1929 – Robert Sergeson Central Alloy Steel – Canton, OHCentral Alloy Steel – Canton, OH Varying Al content in nitro alloy steel with effect Varying Al content in nitro alloy steel with effect

of nickelof nickel

Ferritic Nitrocarburizing (FNC)Ferritic Nitrocarburizing (FNC)Continued 4Continued 4

V. O. Homberg & J.P. Walsted - MITV. O. Homberg & J.P. Walsted - MIT Effect of varying temperature – white layerEffect of varying temperature – white layer Equipment preheat and decarburization effectEquipment preheat and decarburization effect

Dr. Carl F. Floe – Assoc MITDr. Carl F. Floe – Assoc MIT Continued study of white (epsilon) layerContinued study of white (epsilon) layer The Flow Process – methods to change compound layerThe Flow Process – methods to change compound layer

Eventually this research lead to “Ion Nitriding” – in effort to Eventually this research lead to “Ion Nitriding” – in effort to shorten cycle times, reduce distortion, and improve shorten cycle times, reduce distortion, and improve metallurgical propertiesmetallurgical properties..

Ferritic Nitrocarburizing (FNC)Ferritic Nitrocarburizing (FNC)OthersOthers

Fluidized Bed Nitriding and FNCFluidized Bed Nitriding and FNC NitemperingNitempering Controlled NitrocarburizingControlled Nitrocarburizing Soft NitridingSoft Nitriding TrinidingTriniding Nitroc ProcessNitroc Process Vacuum NitrocarburizingVacuum Nitrocarburizing Nitrotec ProcessNitrotec Process Austenite NitrocarburizingAustenite Nitrocarburizing

Types of NitridingTypes of Nitriding

Process where NProcess where N22,C, and sometimes a ,C, and sometimes a very small degree of Overy small degree of O22 atoms are atoms are diffused into the surface of a ferrous diffused into the surface of a ferrous substrate forming a compound layer substrate forming a compound layer and subsurface diffusion layer.and subsurface diffusion layer.

Done in relatively short period of time Done in relatively short period of time at sub critical steel temperaturesat sub critical steel temperatures

Wear properties, Corrosion (solder), Wear properties, Corrosion (solder), and improved fatigue resistance.and improved fatigue resistance.

FNC – Thermochemical DiffusionFNC – Thermochemical Diffusion

Salt Bath NitrocarburizingSalt Bath Nitrocarburizing Started about 55 years ago Started about 55 years ago

commercially.commercially. 1959 – Germany patented Tuffride1959 – Germany patented Tuffride 1970’s – EPA regs prohibiting 1970’s – EPA regs prohibiting

cyanide base materialscyanide base materials Tufftride replaced with Melonite Tufftride replaced with Melonite

and French process called Sur-sulfand French process called Sur-sulf These two processes still in use These two processes still in use

today.today.

Prominent Developments FNCProminent Developments FNC

Gas – Originally patented in 1961 Gas – Originally patented in 1961 by Joseph Lucas Industries Ltd.by Joseph Lucas Industries Ltd.

1965 – B. Presnosil Published 1965 – B. Presnosil Published results of study doing Gas.results of study doing Gas.

During following quarter of a During following quarter of a century – developed Triniding (NHcentury – developed Triniding (NH33 and exothermic gas), Nitemper, and exothermic gas), Nitemper, Lindure and a two stage process Lindure and a two stage process (Deganit) from Germany(Deganit) from Germany

Prominent Developments FNCProminent Developments FNCContinuedContinued

An 1879 patent discusses baking minerals An 1879 patent discusses baking minerals under fluidized bed conditions under fluidized bed conditions

Bed of finely-divided heated particles, usually Bed of finely-divided heated particles, usually Aluminum oxide made to behave like a liquid Aluminum oxide made to behave like a liquid by moving exothermic and reactive gases by moving exothermic and reactive gases through the mediumthrough the medium Smooth or bubbly properties – determines Smooth or bubbly properties – determines

fluidization quality.fluidization quality. Size and hetrogeneity (other offspring) of bubbles Size and hetrogeneity (other offspring) of bubbles

– influences rate of the solid mixing– influences rate of the solid mixing Bed geometry, gas flow rate, type of gas Bed geometry, gas flow rate, type of gas

distributordistributor Vessel features – baffles, screens, heat Vessel features – baffles, screens, heat

exchangersexchangers

Fluidized (FNC) Bed PhenomenonFluidized (FNC) Bed Phenomenon

Plunging your hand into a fluidized bed Plunging your hand into a fluidized bed (unheated of course) gives the sensation of (unheated of course) gives the sensation of placing your hand in a bucket of water. Light placing your hand in a bucket of water. Light objects introduced in the bed will float if light objects introduced in the bed will float if light enough.enough.

Behaving as a liquid causes the entire Behaving as a liquid causes the entire introduced object (metal) to be in complete introduced object (metal) to be in complete contact with the aluminum oxide separated by contact with the aluminum oxide separated by the reactive gas/gases that surround the the reactive gas/gases that surround the media and cause diffusion and white layer media and cause diffusion and white layer creation.creation.

The heat from the bed starts the diffusionThe heat from the bed starts the diffusion

Analogy of Fluidized Bed and LiquidsAnalogy of Fluidized Bed and Liquids

Cleanliness of tool steelCleanliness of tool steel Mild to aggressive alkaline bath at elevated Mild to aggressive alkaline bath at elevated

temperature – bed & part contaminationtemperature – bed & part contamination

Particle diameter – influences heat Particle diameter – influences heat transfertransfer In practice 100 micro mm (.3940 micro inches)In practice 100 micro mm (.3940 micro inches)

Bed material densityBed material density Optimum value 1280-1600 kg/cu m or 80-100lb/cu. ft.Optimum value 1280-1600 kg/cu m or 80-100lb/cu. ft.

Fluidized velocity of gas/gasesFluidized velocity of gas/gases

Fluidized (FNC) Heat Fluidized (FNC) Heat Transfer FactorsTransfer Factors

Optimizing gas/gases flow rateOptimizing gas/gases flow rate Between 2 to 3 times the minimum fluidization Between 2 to 3 times the minimum fluidization

velocityvelocityCurve peakingCurve peaking

To high – particle entrapment – high gas To high – particle entrapment – high gas consumptionconsumption

To low - poor heat transfer – lack of To low - poor heat transfer – lack of uniformityuniformity Bed screws do not provide consistencyBed screws do not provide consistency

Optimizing heat transfer to bedOptimizing heat transfer to bed

Relationship of gas fluidization velocity Relationship of gas fluidization velocity to heat transfer rateto heat transfer rate

Heat transfer rate falls off rapidly

Relationship of Bed Temperature Relationship of Bed Temperature to necessary Flow Rateto necessary Flow Rate

Higher bed temperatures require

less gas flow

Objective to get maximum heat Objective to get maximum heat transfer to part and optimize velocity transfer to part and optimize velocity

of the gas/gasesof the gas/gases

Heat transfer rate falls off rapidly without optimized gas flow rate

Higher bed temperatures require less gas flow

Computer control and automationComputer control and automationAdjustable ceramic screensAdjustable ceramic screensEclipse valves with flow metersEclipse valves with flow metersSensor feedback to computer Sensor feedback to computer

controls and automation systemcontrols and automation system

Now a better way to attain Now a better way to attain repeatability - flow and heatrepeatability - flow and heat

First Fully Automated System in theUnited States and Canada

H-13 after only 2 hours in bed H-13 after only 2 hours in bed (N(N22,NH,NH33,CH,CH44))

Compound layer 5-20 microns = .0002-.0008 inchesDiffusion layer 102-203 microns = .004-.008 inches

Vickershardness

from surface

Development of Hard PVD (below 700Development of Hard PVD (below 700oo F) F) thermochemical surface treatments in thermochemical surface treatments in Australia – grant by IR & D boardAustralia – grant by IR & D board

Coatings such as vanadium carbonitride, Coatings such as vanadium carbonitride, and chromium carbonitride at low and chromium carbonitride at low temperature by diffusion-based temperature by diffusion-based treatmentstreatments

Patents already applied for and equipment Patents already applied for and equipment available to perform new range of low available to perform new range of low temperature surface treatments – Qab.temperature surface treatments – Qab.

Future Uses of Fluidized BedsFuture Uses of Fluidized Beds

Range of coatings - QABRange of coatings - QAB

Nitrogen and Alloy based below 700o CCarbon based above 700o C

Courtesy of QHTRay Reynoldson

Nitrogen BasedNitridingFerriticAustenitic

Alloy BasedChromiumVanadiumTitaniumNiobium

Carbon BasedCarburizingCD CarburizingCarbonitriding

Process to form CrCN - QABProcess to form CrCN - QAB

Aluminum Oxide media to obtain CrCN is coated

Courtesy of QHTRay Reynoldson

Hardness Profile - QABHardness Profile - QAB

Qab Profile for CrCN and Nitrocarburized structure

Courtesy of QHTRay Reynoldson

Thickness controlled by time of processing

CrCN = 1550v

NitroC = 950v

Distribution of Elements in White LayerDistribution of Elements in White Layer

% of Cr highest near surface

Thickness controlled by time of processing

CrCN = 1550v

NitroC = 950v

Courtesy of QHTRay Reynoldson

Field test results CrCNField test results CrCN

Courtesy of QHTRay Reynoldson

TOOLING CIRCLE OF LIFE

TOOLING CYCLE OF

LIFE

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