Nitriding Iron at Lower Temperatures

Tong, Weiping; Tao, Nengguo; Wang, Z. B.; Lü, Jian; Lu, K.

doi:10.1126/science.1080216

Cited by 597 publications

(319 citation statements)

References 13 publications

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“…9,10 Therefore, understanding the underlying mechanisms of grain refinement induced by plastic straining is crucial, especially at the nanometer scale. On one hand, understanding the mechanism of strain-induced grain refinement is crucial for development of synthesis techniques that are oriented toward practical applications for engineering materials.…”

Section: Introductionmentioning

confidence: 99%

Grain refinement at the nanoscale via mechanical twinning and dislocation interaction in a nickel-based alloy

et al. 2004

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A nanostructured surface layer was formed on an Inconel 600 plate by subjecting it to surface mechanical attrition treatment at room temperature. Transmission electron microscopy and high-resolution transmission electron microscopy of the treated surface layer were carried out to reveal the underlying grain refinement mechanism. Experimental observations showed that the strain-induced nanocrystallization in the current sample occurred via formation of mechanical microtwins and subsequent interaction of the microtwins with dislocations in the surface layer. The development of high-density dislocation arrays inside the twin-matrix lamellae provides precursors for grain boundaries that subdivide the nanometer-thick lamellae into equiaxed, nanometer-sized grains with random orientations.

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Section: Introductionmentioning

confidence: 99%

Grain refinement at the nanoscale via mechanical twinning and dislocation interaction in a nickel-based alloy

et al. 2004

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“…[30] Several studies have reported that surface mechanical attrition treatment (SMAT) produces a nanocrystalline layer on various surfaces by using balls (4-10 mm in diameter) to repeatedly and multi-directionally impact a work piece. [14,23] Although the grain refinement mechanism of the MSB technique is similar to that of SMAT, the energy of the shot particles ejected by MSB is far lower due to the smaller shot sizes (1.6 mm in diameter), and the shot impacts the workpiece multidirectionally during SMAT rather than unidirectionally during MSB. Therefore, it is more difficult to achieve surface nanocrystallization on a titanium plate using MSB than SMAT, but it is easier to achieve surface grain refinement.…”

Section: Resultsmentioning

confidence: 99%

“…[14,15] Currently, there are many severe plastic deformation (SPD) techniques for achieving surface nanocrystallization (SNC) on various materials, such as surface mechanical attrition treatment (SMAT), [16,17] surface mechanical grinding treatments (SMGT), [18] ultrasonic shot peening (USSP), [19,20] laser shock processing (LSP), [21] and high pressure torsion (HPT). [22] However, neither SNC nor enhanced kinetics have been studied on the surface of a large-sized titanium plate.…”

Section: Introductionmentioning

confidence: 99%

Influence of Ultrafine‐Grained Layer on Gaseous Nitriding of Large‐Sized Titanium Plate

et al. 2017

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In this paper, mechanical shot blasting on a large sized titanium plate is conducted to induce severe plastic deformation, which generates an ultrafinegrained surface layer. The effect of an ultrafine-grained layer on nitriding is evaluated at nitriding temperatures from 600 to 850 C. The structural phases and mechanical property improvements are investigated and compared to those of a coarse-grained specimen by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and mechanical property measurements. The results indicate that an ultrafine-grained layer enhances the nitriding kinetics and produces a thicker nitrided layer than that of a coarse-grained plate at the same gaseous nitriding temperatures. The improved kinetics are attributed to a greater number of grain boundaries and defects introduced into the titanium plate surface by the mechanical shot blasting treatment. Meanwhile, the surface and cross-sectional hardness values improve compared to the coarse-grained plate due to the thicker nitrided layer resulting from deeper nitrogen diffusion.

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“…This technique is of great industrial interest as it forms a unique composite structure with a hard surface (nitride compounds layer) and tough interior so that the global mechanical performance and wear/corrosion resistance of alloys and steels could be greatly improved [1]. However, nitriding processes are performed at high temperatures (above 773 K) for a long duration (20 ∼ 80 h) and may induce serious deterioration of the substrate for many material families.…”

Section: Introductionmentioning

confidence: 99%

Nitriding of nanocrystalline pure Fe induced by surface mechanical attrition treatment

Tong

Gong

et al. 2015

MATEC Web of Conferences

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Abstract. Properties of nanocrystalline (nc) materials are different from, and often superior to those of conventional coarse-grained counterparts. Unfortunately, it is still difficult to obtain "ideal" (e.g. full-density, residual stress-free, flaw-free, porosity-free and contamination-free) nc bulk sample by using the present preparation methods. Recently, a new technique named surface mechanical attrition treatment (SMAT) was developed. SMAT enables the fabrication of an nc surface layer on various bulk metals. The nc layer is free of contamination and porosity because the nanocrystallization process is induced by the severe plastic deformation at very high strain rates. In this work, a pure Fe plate was subjected to the SMAT and its microstructure were characterized. The effect of the surface nanocrystalline layer on the gas nitriding process at a lower temperature was also investigated by using structural analysis. The surface nanocrystallization evidently enhances nitriding kinetics and promotes the formation of an ultra-fine polycrystalline compound layer. The results of the investigation showed that this new gas nitriding technique can effectively increase the hardness of the resulting surface layer in comparison with conventional nitriding, demonstrating a significant advancement for materials processing.

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Nitriding Iron at Lower Temperatures

Cited by 597 publications

References 13 publications

Grain refinement at the nanoscale via mechanical twinning and dislocation interaction in a nickel-based alloy

Grain refinement at the nanoscale via mechanical twinning and dislocation interaction in a nickel-based alloy

Influence of Ultrafine‐Grained Layer on Gaseous Nitriding of Large‐Sized Titanium Plate

Nitriding of nanocrystalline pure Fe induced by surface mechanical attrition treatment

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