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Jerzy Nowacki - One of the best experts on this subject based on the ideXlab platform.
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influence of initial Heat Treatment of 17 4 ph stainless Steel on gas nitriding kinetics
Surface & Coatings Technology, 2008Co-Authors: P Kochmanski, Jerzy NowackiAbstract:Results of the investigation of nitrided layers on 17-4 PH type precipitation hardening stainless Steel are presented in this paper. The layers have been produced in the process of gas nitriding in a partly dissociated ammonia at temperatures between 410 and 570 °C. Hydrogen chloride admixture to active atmosphere was used as a surface activator. Structure of the nitrided layers were examined using scanning and transmission electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. The influence of the initial Steel Heat Treatment on the nitriding kinetics has been considered. 17-4 PH stainless Steel was nitrided at various Heat Treatment conditions, i.e. after solution Treatment or ageing at different temperatures. The influence of precipitation processes taking place during the Heat Treatment before nitriding on the diffusive process kinetics was proven. It was found that, that increasing of Steel ageing temperature up to 600 °C before nitriding effects on an increasing of the nitriding kinetics.
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activated gas nitriding of 17 4 ph stainless Steel
Surface & Coatings Technology, 2006Co-Authors: P Kochmanski, Jerzy NowackiAbstract:Results of the investigation of nitrided precipitation-hardened Steel 17-4 PH surface have been presented. The layers have been created as a result of the gas nitriding process in a partly dissociated ammonia. Hydrogen chloride admixture to ammonia was used as a Steel surface activator. The influence of the Steel Heat Treatment before nitriding on the diffusive process has been considered. 17-4 PH stainless Steel in various states of Heat Treatment, i.e. in supersaturated or precipitation-hardened state was nitrided. The nitrided layers were studied by scanning electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. Microhardness tests of the layers using Vickers method has been done too. Hardness of the generated layers reached 1700 HV. The optimal temperature range of the thermo-chemical Treatment was determined. The influence of precipitation processes taking place during the Heat Treatment before nitriding on kinetics of diffusive nitriding process, surface geometry and the created layer properties has been proved. The tests results showed, that nitrided layers thickness is bigger on a base of the 17-4 PH stainless Steel in precipitation-hardened, than in supersaturated state. Increase of Steel ageing temperature before nitriding caused an increase of the nitriding process intensity. Differences of surface morphology, thickness, phase composition and nitrogen concentration of the diffusion layers created at the same nitriding conditions, but various conditions of 17-4 PH Steel Heat Treatment before nitriding have been observed.
John G Speer - One of the best experts on this subject based on the ideXlab platform.
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Quenching and Partitioning Steel Heat Treatment
Metallography Microstructure and Analysis, 2013Co-Authors: Li Wang, John G SpeerAbstract:Quenching and partitioning (QP property advancements continue to be made through research on this emerging technology. Early investigations [1] also proposed a corresponding thermodynamic model for Q&P Steel and its Heat Treatment, which is now referred to as constrained carbon equilibrium [3]. Since first proposed in 2003, Q&P Steel has gained interest for its potential to enhance properties of strength and ductility with compositions similar to transformationinduced plasticity (TRIP) Steel and has been proposed as a third-generation automotive Steel (Fig. 1) [4]. Many researchers [5–17] have investigated the relationship between properties and microstructures of Q&P Steels subjected to various Heat Treatments and showed that the ultrahigh strength of Q&P Steel results from martensite laths, while its good ductility is attributed to TRIP-assisted behavior of retained austenite during deformation. De Moor et al. [14] examined the stability of retained austenite and showed that the TRIP effect occurs in Q&P Steels, thereby effectively contributing to the significant strain hardening. Santofimia et al. [15, 16] and Takahama et al. [17] analyzed microstructural evolution during annealing Editor’s Note The following is a preview chapter from the upcoming volume Steel Heat Treating Fundamentals and Processes, Volume 4A, ASM Handbook, Jon Dossett and George Totten, editors. The volume is scheduled for publication later this year.
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Calorimetric study of carbon partitioning from martensite into austenite Steel
Physical Review B, 2010Co-Authors: Emmanuel De Moor, Amy J. Clarke, Cecilia Föjer, J. Penning, John G SpeerAbstract:Quenching and partitioning (Q and P) has been developed as a novel Steel Heat Treatment to produce advanced high-strength microstructures consisting of a martensitic matrix containing significant amounts of retained austenite. Austenite stabilization is hypothesized to result from decarburization of the martensite and transport into the austenite. Differential scanning calorimetry was employed to study Q and P microstructures. Two exothermic events were observed when Heating a Q and P sample from room temperature to 600 deg. C. An activation energy suggesting a mechanism controlled by carbon diffusion in bcc iron is obtained for the first peak which is believed to be associated with carbon partitioning. The second peak is believed to be associated with austenite decomposition.
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carbon partitioning to austenite from martensite or bainite during the quench and partition q p process a critical assessment
Acta Materialia, 2008Co-Authors: R E Hackenberg, F C Rizzo, Kester D Clarke, A. J. Clarke, M.k. Miller, D V Edmonds, John G Speer, David K Matlock, Emmanuel De MoorAbstract:Abstract The goal of the quench and partition (Q&P) process for Steel Heat Treatment is to enrich austenite with carbon during a partitioning Treatment after initial quenching below the martensite start temperature ( M s ). Two proposed mechanisms for austenite carbon enrichment during partitioning include carbon transport from martensite and/or the formation of carbide-free bainite. Theoretical calculations show experimentally measured austenite fractions are difficult to explain based upon a mechanism involving solely bainite formation. Carbon partitioning from martensite provides a more satisfactory explanation, although the formation of bainite during partitioning cannot be completely excluded.
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Microstructural Features of 'Quenching and Partitioning': A New Martensitic Steel Heat Treatment
Materials Science Forum, 2007Co-Authors: David V. Edmonds, F C Rizzo, David K Matlock, Michael K Miller, Amy J. Clarke, John G SpeerAbstract:The microstructure following a new martensite Heat Treatment has been examined, principally by high-resolution microanalytical transmission electron microscopy and by atom probe tomography. The new process involves quenching to a temperature between the martensite-start (Ms) and martensite-finish (Mf) temperatures, followed by ageing either at or above, the initial quench temperature, whereupon carbon can partition from the supersaturated martensite phase to the untransformed austenite phase. Thus the Treatment has been termed ‘Quenching and Partitioning’ (Q&P). The carbon must be protected from competing reactions, primarily carbide precipitation, during the first quench and partitioning steps, thus enabling the untransformed austenite to be enriched in carbon and largely stabilised against further decomposition to martensite upon final quenching to room temperature. This microstructural objective is almost directly opposed to conventional quenching and tempering of martensite, which seeks to eliminate retained austenite and where carbon supersaturation is relieved by carbide precipitation. This study focuses upon a Steel composition representative of a TRIP-assisted sheet Steel. The Q&P microstructure is characterised, paying particular attention to the prospect for controlling or suppressing carbide precipitation by alloying, through examination of the carbide precipitation that occurs.
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quenching and partitioning martensite a novel Steel Heat Treatment
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: D V Edmonds, F C Rizzo, David K Matlock, K He, B C De Cooman, John G SpeerAbstract:Abstract A novel concept for the Heat Treatment of martensite, different to customary quenching and tempering, is described. This involves quenching to below the martensite-start temperature and directly ageing, either at, or above, the initial quench temperature. If competing reactions, principally carbide precipitation, are suppressed by appropriate alloying, the carbon partitions from the supersaturated martensite phase to the untransformed austenite phase, thereby increasing the stability of the residual austenite upon subsequent cooling to room temperature. This novel Treatment has been termed ‘quenching and partitioning’ (Q&P), to distinguish it from quenching and tempering, and can be used to generate microstructures with martensite/austenite combinations giving attractive properties. Another approach that has been used to produce austenite-containing microstructures is by alloying to suppress carbide precipitation during the formation of bainitic structures, and interesting comparisons can be made between the two approaches. Moreover, formation of carbide-free bainite during the Q&P partitioning Treatment may be a reaction competing for carbon, although this could also be used constructively as an additional stage of Q&P partitioning to form part of the final microstructure. Amongst the ferrous alloys examined so far are medium carbon bar Steels and low carbon formable TRIP-assisted sheet Steels.
Silvio E. Kruger - One of the best experts on this subject based on the ideXlab platform.
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Influence of Steel Heat Treatment on ultrasonic absorption measured by laser ultrasonics
Materials Science and Engineering: A, 2004Co-Authors: Guy Lamouche, Stéphane Bolognini, Silvio E. KrugerAbstract:Laser ultrasonics is combined with the reverberation technique to measure ultrasound absorption during thermal cycles applied to medium-carbon Steel samples. During Heating to the austenitic phase, a small Snoek peak is observed around 360 \ub0C at 10 MHz along with a signature of the ferromagnetic to paramagnetic transition near 768 \ub0C. Upon cooling, the behavior of the internal friction is much different from that of Heating: reduced high-temperature absorption, delayed phase transition, smaller magnetoelastic contribution and stronger Snoek peak are observed. The austenitizing temperature is found to have primary importance on the internal friction behavior during cooling. These measurements show that ultrasound absorption measurements using laser ultrasonics could serve as a basis for a technique to characterize the microstructure evolution of Steel in various temperature ranges.Peer reviewed: YesNRC publication: Ye
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Influence of Steel Heat Treatment on ultrasonic absorption measured by laser ultrasonics
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Guy Lamouche, Stéphane Bolognini, Silvio E. KrugerAbstract:Abstract Laser ultrasonics is combined with the reverberation technique to measure ultrasound absorption during thermal cycles applied to medium-carbon Steel samples. During Heating to the austenitic phase, a small Snoek peak is observed around 360 °C at 10 MHz along with a signature of the ferromagnetic to paramagnetic transition near 768 °C. Upon cooling, the behavior of the internal friction is much different from that of Heating: reduced high-temperature absorption, delayed phase transition, smaller magnetoelastic contribution and stronger Snoek peak are observed. The austenitizing temperature is found to have primary importance on the internal friction behavior during cooling. These measurements show that ultrasound absorption measurements using laser ultrasonics could serve as a basis for a technique to characterize the microstructure evolution of Steel in various temperature ranges.
P Kochmanski - One of the best experts on this subject based on the ideXlab platform.
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influence of initial Heat Treatment of 17 4 ph stainless Steel on gas nitriding kinetics
Surface & Coatings Technology, 2008Co-Authors: P Kochmanski, Jerzy NowackiAbstract:Results of the investigation of nitrided layers on 17-4 PH type precipitation hardening stainless Steel are presented in this paper. The layers have been produced in the process of gas nitriding in a partly dissociated ammonia at temperatures between 410 and 570 °C. Hydrogen chloride admixture to active atmosphere was used as a surface activator. Structure of the nitrided layers were examined using scanning and transmission electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. The influence of the initial Steel Heat Treatment on the nitriding kinetics has been considered. 17-4 PH stainless Steel was nitrided at various Heat Treatment conditions, i.e. after solution Treatment or ageing at different temperatures. The influence of precipitation processes taking place during the Heat Treatment before nitriding on the diffusive process kinetics was proven. It was found that, that increasing of Steel ageing temperature up to 600 °C before nitriding effects on an increasing of the nitriding kinetics.
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activated gas nitriding of 17 4 ph stainless Steel
Surface & Coatings Technology, 2006Co-Authors: P Kochmanski, Jerzy NowackiAbstract:Results of the investigation of nitrided precipitation-hardened Steel 17-4 PH surface have been presented. The layers have been created as a result of the gas nitriding process in a partly dissociated ammonia. Hydrogen chloride admixture to ammonia was used as a Steel surface activator. The influence of the Steel Heat Treatment before nitriding on the diffusive process has been considered. 17-4 PH stainless Steel in various states of Heat Treatment, i.e. in supersaturated or precipitation-hardened state was nitrided. The nitrided layers were studied by scanning electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. Microhardness tests of the layers using Vickers method has been done too. Hardness of the generated layers reached 1700 HV. The optimal temperature range of the thermo-chemical Treatment was determined. The influence of precipitation processes taking place during the Heat Treatment before nitriding on kinetics of diffusive nitriding process, surface geometry and the created layer properties has been proved. The tests results showed, that nitrided layers thickness is bigger on a base of the 17-4 PH stainless Steel in precipitation-hardened, than in supersaturated state. Increase of Steel ageing temperature before nitriding caused an increase of the nitriding process intensity. Differences of surface morphology, thickness, phase composition and nitrogen concentration of the diffusion layers created at the same nitriding conditions, but various conditions of 17-4 PH Steel Heat Treatment before nitriding have been observed.
Guy Lamouche - One of the best experts on this subject based on the ideXlab platform.
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Influence of Steel Heat Treatment on ultrasonic absorption measured by laser ultrasonics
Materials Science and Engineering: A, 2004Co-Authors: Guy Lamouche, Stéphane Bolognini, Silvio E. KrugerAbstract:Laser ultrasonics is combined with the reverberation technique to measure ultrasound absorption during thermal cycles applied to medium-carbon Steel samples. During Heating to the austenitic phase, a small Snoek peak is observed around 360 \ub0C at 10 MHz along with a signature of the ferromagnetic to paramagnetic transition near 768 \ub0C. Upon cooling, the behavior of the internal friction is much different from that of Heating: reduced high-temperature absorption, delayed phase transition, smaller magnetoelastic contribution and stronger Snoek peak are observed. The austenitizing temperature is found to have primary importance on the internal friction behavior during cooling. These measurements show that ultrasound absorption measurements using laser ultrasonics could serve as a basis for a technique to characterize the microstructure evolution of Steel in various temperature ranges.Peer reviewed: YesNRC publication: Ye
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Influence of Steel Heat Treatment on ultrasonic absorption measured by laser ultrasonics
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Guy Lamouche, Stéphane Bolognini, Silvio E. KrugerAbstract:Abstract Laser ultrasonics is combined with the reverberation technique to measure ultrasound absorption during thermal cycles applied to medium-carbon Steel samples. During Heating to the austenitic phase, a small Snoek peak is observed around 360 °C at 10 MHz along with a signature of the ferromagnetic to paramagnetic transition near 768 °C. Upon cooling, the behavior of the internal friction is much different from that of Heating: reduced high-temperature absorption, delayed phase transition, smaller magnetoelastic contribution and stronger Snoek peak are observed. The austenitizing temperature is found to have primary importance on the internal friction behavior during cooling. These measurements show that ultrasound absorption measurements using laser ultrasonics could serve as a basis for a technique to characterize the microstructure evolution of Steel in various temperature ranges.
