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Topic: Carburization

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	Direct reduction reactor with hot discharge - United States Patent 4,734,128
		A method is disclosed for the gaseous reduction of iron ore to sponge iron at a given degree of carburization and yet at a temperature suitable for hot briquetting or for direct feed to a melter or to a refining furnace.
		The desired percentage of carburization and the preferred elevated temperature are achieved by using a hot blend of recycled reducing gas and essentially uncracked natural gas or methane to carburize and to decrease the temperature of the sponge iron in the cooling zone of the reactor.
		The carburizing gas used is formed by blending a portion of the recycle gas that is at a relatively high temperature and a stream of natural gas or methane that is at a lower non-cracking temperature than the recycle stream.
	xrint.com /patents/us/4734128 (2926 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Carburization is not a common occurrence in most refining operations because of the relatively low tube temperatures of most refinery fired heaters.
		Carburization is a serious problem in these furnaces because of the high tube metal temperatures - up to 2100F (1149C) - and high carbon potential associated with the ethane, propane, naphtha and other hydrocarbon feedstock which are cracked.
		As in the case of carburization, higher nickel alloys are very resistant to nitridation attack due to the low solubility of nitrogen in nickel.
	www.nickelinstitute.org /index.cfm/ci_id/10624.htm (8218 words)

	Carburization - Wikipedia, the free encyclopedia
		Carburization (often referred to as carburizing) is the name of the process by which carbon is introduced into a metal.
		Carburization of steel generally involves a heat treatment of the metallic surface using a gaseous, liquid, solid or plasma source of carbon.
		Plasma carburizing is increasingly used in industry to improve the surface characteristics (such as wear and corrosion resistance, hardness and load-bearing capacity) of various metals, notably stainless steels.
	en.wikipedia.org /wiki/Carburization (374 words)

	Carburization resistant high temperature alloy - Patent 4388125
		The excellent carburization resistance is attributed to the pervading presence of aluminum which when allowed to oxidize to alumina in surface regions forms a diffusion barrier to inhibit carbon penetration.
		This is the level required for excellent carburization resistance and strength without significantly decreasing the metal fluidity during casting.
		A comparison of the carburization resistance, sulfidation resistance and oxidation resistance in Table III clearly shows the superiority to resistance of the alloys of the current invention over the alloys commercially available.
	www.freepatentsonline.com /4388125.html (3087 words)

	Seamless tube and pipe Corrosion resistance
		The degree of carburization depends on the composition of the material and on the carbon and oxygen contents.
		The material carburizes in gases with low oxygen content, but the depth of penetration is limited by the high content of chromium and nickel.
		In alternately oxidizing and carburizing atmospheres, alloys of high nickel content are sometimes attacked by what is known as "green rot".
	www.sandvik.com /sandvik/0140/internet/se01598.nsf/cdatas/271CA4BC5E8AAAD0412566410055982D (580 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Carburization of austenitic stainless steel is typically a challenge: at high temperatures of 550 to 850Â°C, chromium carbides are generated in the metal, and these are then precipitated at grain boundaries where they can lead to intergranular corrosion.
		The new carburization process improves the wear resistance, galling and seizing characteristics of stainless steel in nut-and-bolt applications.
		Carburized stainless steel has been used commercially by a major manufacturer for a threaded lid on a beverage processing vessel.
	www.nickelinstitute.org /index.cfm/ci_id/12760.htm (293 words)

	Method for brazing with simultaneous carburization - Patent 5131585
		Carburization is also known to improve anti-abrasion and anti-fatigue characteristics of outer surfaces of ferric articles by having carbon penetrated from the outer surfaces and diffused inwardly to form hardened layers.
		Carburization is made at a certain stage during articles proceed in a furnace and are heated and cooled from 900 to 1,130.degree.
		Although the articles are subjected to carburization for 4 to 5 minutes only among said 15 to 30 minutes, they are carburized well in this invention to have a carburization depth of 0.3 to 0.4mm, primarily on account of the carburization being made in this invention at a temperature as high as 1,100.degree.
	www.freepatentsonline.com /5131585.html (2038 words)

	Carburization Mechanisms of Stainless Steels in Steam Generators (Site not responding. Last check: 2007-10-21)
		The typical cases of carburization reported in the literature are associated with temperatures usually higher than 700°C in highly reducing atmospheres.
		In steam generators, the carburization phenomenon is difficult to explain because the metal temperature is typically lower than 600°C and the environments around the tubes are combustion flue gases which are basicaUy oxidant due to the combustion process is carried out using an air excess over the stoichiometric required for the fuel combustion.
		In México there are many carburization cases associated with high corrosion rates or tube failures in the high temperature zone of steam generators compared to other countries.
	ce.eng.usf.edu /research_labs/corrosion/pg43.html (288 words)

	Gear Solutions Online: Features: Engineered Heat Treatment for Stronger Aerospace Gears, July 2006
		While carburization is designed to achieve surface compression in quenched parts by delaying formation of surface martensite, the potential for intensive quenching to foster additional enhancement was a key factor of this investigation.
		To most accurately capture the combined carburizing and geometry effects of a Pyrowear gear, the notched test bars were carburized only on the top surface (including the notch), as shown schematically in (Figure 2).
		Prior to quench hardening, the gears were vacuum carburized selectively on the teeth surfaces, with copper plating masking the balance of the gear as shown in the related figure.
	www.gearsolutionsonline.com /articles/DCT0706.html (5041 words)

	Reducing Instabilities in Advanced Nickel-Base Superalloys (Site not responding. Last check: 2007-10-21)
		Successful carburization eliminates instabilities under the diffusion zone by forming submicron carbides and changing the local chemistry of the superalloy.
		Carburization is most effective when it is preceded by a stress relief heat treatment and adequate surface preparation.
		One such technique is carburization, which changes the local chemistry by forming submicron carbides near the surface of the superalloy.
	www.grc.nasa.gov /WWW/RT2001/5000/5100mackay.html (799 words)

	The eBearing Glossary of Bearing Industry Terms > C (Site not responding. Last check: 2007-10-21)
		Carburization is a variety of case hardening which produces a carbon gradient extending inward from the surface.
		This enables the surface layer to be hardened either by quenching directly from the carburizing temperature or by cooling to room temperature then reaustenitizing and quenching.
		The hardening processes most commonly used are carburizing, cyaniding, nitrifying and carbonitriding.
	www.ebearing.com /glossary/c.html (567 words)

	Corrosion of metals in hot corrosive gases, Manufacturing News, Jobwerx.com -
		X-ray analysis by diffraction of the surface scale, and analysis of the gas, are common methods to confirm carburization.
		The time dependence of carburization has been reported to be parabolic (metal carburization proportional to the square root of time).
		One thousand hours may be required to establish the time dependence expected for long-term service, suggesting that carburization rates measured after penods of only hundreds of hours (as is often the case for available data) may not be useful in estimating carburization corrosion rates for long-term service.
	www.jobwerx.com /news/Archives/metalsandcorrosives.html (2585 words)

	Ancient carburisation of iron to steel: a comment
		Rehder (1989) argues that it is impossible to carburize iron to steel in a forge hearth.
		In a recent article in Archeomaterials J. Rehder (1989: 30-32) argues that carburization of iron in a forge hearth is a practical impossibility: "To carburize iron, it must be enclosed with a source of carbon so as to exclude all or nearly all the products of combustion" (p.
		To understand the text it is only necessary to note that Evenstad apparently assumes the use of a hearth with a sand firebed and with a horizontal tuyère blowing from the side.
	www.staff.hum.ku.dk /dbwagner/REHD/REHD.html (3121 words)

	Gear Solutions Online: Features: The Simultaneous Dual Frequency Method of Inductive Gear Hardening by Wolfgang ...
		In addition to traditional carburization, there are several inductive methods which can be applied to protect these gears from wear, but all have their limitations.
		As noted earlier, carburization has been the most reliable way of hardening gears, but it requires a lot of time and uses a lot of energy, as well as space.
		Unlike carburization, we potentially have total control of the quality of the part, because engineers know the tolerances of the materials used, the power is known, and how long it has been applied.
	www.gearsolutionsonline.com /articles/eldec0503.html (2505 words)

	[No title]
		This project is about modeling the carburization process to visualize the effects of various parameters on the carburization process.
		Using ThermoCalc as a database, we are in the process of modeling the carburization process, considering the various parameters and their influence on the process.
		Carburizing is classified as a common practice in the heat treatment technique.
	www.iit.edu /~shekviv/index.htm (588 words)

	330 Plate - Heat, Corrosion Resistant Alloy - Rolled Alloys
		RA330 is an austenitic heat and corrosion resisting alloy offering an exceptional combination of strength and resistance to carburization, oxidation and thermal shock.
		Carburization and oxidation resistance to 2200°F are enhanced by a nominal 1.25% silicon addition.
		RA330 finds wide applications in high temperature industrial environments where good resistance to the combined effects of carburization and thermal cycling is a prime requisite.
	www.rolledalloys.com /trc/heatra330.aspx (89 words)

	HAYNES 556 alloy Carburization Resistance
		556 alloy has excellent resistance to carburization, as measured in both mixed gas exposure tests and packed graphite exposure tests.
		In particular, the resistance to carburization of 556 alloy was significantly better than that for the stainless steel type materials.
		Note: Alloy 617 is carburized to the center of the sample.
	www.haynesintl.com /556H3013E/556cr.htm (273 words)

	corrosioneering - pyrolysis furnaces
		Carburization increases with temperature; the rate roughly doubles for every 100 F tube metal temperature rise (See Figure 2).
		Cr and carbon control the rupture strength through carbide formation and Nb is a solid solution strengthener as are W and Mo. They and micro additions of Ti, Zr and other reactive metals produce extremely fine carbides and participate in the carbide formation and strengthening of the alloy.
		Table 1 provides an overall ranking of materials, using creep-rupture strength, carburization resistance and highest service temperature limit as the selection criteria.
	www.intercorr.com /pyrolysis.htm (546 words)

	EVALUATION OF CARBURIZATION DEPTH IN SERVICE EXPOSED FERRITIC STEEL USING MAGNETIC BARKHAUSEN NOISE ANALYSIS
		In this study, the use of MBN technique for the evaluation of carburization depth is reported.
		The carburized ID side of the sample shows the lowest MBN peak activity corresponding to the maximum hardness and there is gradual increase in the MBN peak and a decrease in VHN as the distance from ID increases.
		Even though, the cross section of the tube would not be available for MBN measurement in practice, the MBN measurement on the carburized surface (ID) would give the carbon content and/or hardness values of the carburized surface which would help in theoretically predicting the approximate depth of the carburized layer.
	www.ndt.net /abstract/wcndt96/data/624.htm (565 words)

	Evidence for the phenomenon of carburization-decarburization of tungsten carbide (Site not responding. Last check: 2007-10-21)
		Thoriated tungsten filaments acting as the main part of the cathode of magnetrons used for creation of electromagnetic radiation in microwave ovens were partly carburized in order to limit, during the time of operation, the volatilization of thorium.
		The carburization of tungsten being a reversible chemical reaction at high temperature, it is quite possible to carry out carburization-decarburization cycles.
		The interest of this work is to study some parameters leading to the decarburization of partly carburized filaments in order to avoid this phenomenon during fabrication and normal use of magnetrons.
	stacks.iop.org /0022-3727/27/402 (270 words)

	Re: Furnace tubes carburization
		From my expierence, certain grades of austenitic stainless steel tubes that are exposed to reducing atmospheres containing either carbon dioxide/ carbon monoxide or methane can carburize in service resulting in the formation of chromium carbides along the metals grain boundaries.
		Since carburization is a diffusion mechanism, I would use a heat resistant grade of austenitic stainless steel like AISI Type 309 or 310.
		These grades are used in heat treating furnace components with reducing atmospheres that carburize parts all of the time.
	www.steamforum.com /steamforum2003/_discstm/0000071a.htm (249 words)

	Alloy 330 - Heat Resistant Nickel Alloy Plate - Sandmeyer Steel
		The alloy is used extensively in elevated temperatures where resistance to the combined effects of thermal cycling and carburization is required.
		With a nickel content of 34 to 37 percent, the alloy remains highly resistant to both chloride stress corrosion cracking and embrittlement from the precipitation of sigma phase.
		The alloy is used extensively in elevated temperature atmospheres where resistance to the combined effects of thermal cycling and carburization is required.
	www.sandmeyersteel.com /A330.html (737 words)

	Accelerated Corrosion Associated with Carburization of Non-Cooled Boiler Components (Site not responding. Last check: 2007-10-21)
		Evidence of this damage is the intergranular corrosion near the surface and the presence of massive chromium carbides along grain boundaries and inside the grains.
		It was concluded that the unusually high corrosion rate developed by the material of the fastening elements is due to the occurrence of a carburization process associated with high temperature corrosion.
		It has not been found in the literature any precedent of the combination of both phenomena on non-cooled boiler components and we consider it is related to a carburization-corrosion process previously identified on superheater and reheater boilers tubes of some boilers in México.
	ce.eng.usf.edu /research_labs/corrosion/pg42.html (292 words)

	Outokumpu - Steel Properties: Carbon and Nitrogen Pick-up
		Carburization and nitridation are common heat treatment processes in which the surface of the material is intentionally enriched in carbon and/or nitrogen to improve the hardness, the wear resistance, or the fatigue strength of a component.
		Even if the furnace components in these processes are constructed of more resistant materials, the cyclic exposure to the carburizing/nitriding environment will eventually lead to an excessive pick-up of carbon and/or nitrogen.
		carburization due to oil residues on heat treated components and nitridation due to overheating in nitrogen containing gases or to cracking ammonia.
	www.outokumpu.com /pages/Page____5691.aspx (249 words)

	HAYNES 214 alloy Carburization Resistance
		alloy has very good resistance to carburization, as measured in both packed graphite exposure tests and mixed gas exposure tests.
		In particular, the resistance to carburization of 214 alloy was far better than that for the stainless steel type materials.
		Carbon absorption observed for 214 alloy following exposure at both 1700°F (925°C) and 1800°F (980°C) to a carburizing gas mixture was significantly lower than that for all other materials tested.
	www.haynesintl.com /214H3008C/214cr.htm (277 words)

	corrosion in tubing - InterCorr International - corrosion (Site not responding. Last check: 2007-10-21)
		Massive carburization occurred in service due to upset conditions in an ethylene furnace.
		Conditions that caused the failure included excessive temperature in combination with high carbon activity in the process.
		The attack resulted in the formation extensive surface carburization and severe grain boundary carbides which progressed through the material from the I.D. surface.
	www.intercorr.com /mesa.htm (289 words)

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