Micro-/Nano-Structuring in Stainless Steels by Metal Forming and Materials Processing

Aizawa, Tatsuhiko; Shiratori, Tomomi; Komatsu, Takafumi

doi:10.5772/intechopen.91281

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…KAM (kernel angle misorientation) was found to be in fairly good correlation to the equivalent plastic strains [10]. This EBSD analysis has another role, which is to describe the change of crystallographic orientations during the metal forming by using IPF (inverse pole figure) maps [11,12]. As proposed in [13], the induced distortion rate into a single-crystal electrical steel by piercing is composed of the elasto-plastic strain rate and the spin-rotation rate.…”

Section: Introductionmentioning

confidence: 65%

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Quantitative Characterization of the Affected Zones in a Single Crystal Fe-6Si Steel Sheet by Fine Piercing

Aizawa¹,

Shiratori

Yoshino

et al. 2022

Micromachines

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An iron loss in the motor core was often enhanced by formation of plastically affected zones in piercing the electrical steel sheets. A platform methodology to carry out quantitative evaluation of these affected zones in the pierced electrical steel sheets was proposed to search for the way to minimize the affected zone widths. A coarse-grained electrical steel sheet was employed as a work material for a fine piercing experiment under the narrowed clearance between the plasma-nitrided SKD11 punch and core-die. The shearing behavior by the applied loading for piercing was described by in situ measurement of the load-stroke relationship. The plastic straining in the single-crystal electrical steel sheet was characterized by SEM (scanning electron microscopy) and EBSD (electron back-scattering diffraction) to define the affected zone size and to analyze the rotation of crystallographic orientations by the induced plastic distortion during piercing. Integral and differentiation of spin rotation measured the affected zones. The effect of punch edge sharpness on these spin-rotation measures was also discussed using the nitrided and ion-milled SKD11 punch and core-die.

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Section: Introductionmentioning

confidence: 65%

“…maps [11,12]. As proposed in [13], the induced distortion rate into a single-crystal electrical steel by piercing is composed of the elasto-plastic strain rate and the spin-rotation rate.…”

Section: Characterization Of the Straining And Spinning In The Single...mentioning

confidence: 99%

Quantitative Characterization of the Affected Zones in a Single Crystal Fe-6Si Steel Sheet by Fine Piercing

Aizawa¹,

Shiratori

Yoshino

et al. 2022

Micromachines

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“…Since the lower hardness parts are removed by sandblasting, the punch head and die surface are proved to have much higher hardness than their mother substrate materials by plasma nitriding. Various stainless steels and tool steels are available as an original substrate material for this plasma printing [55].…”

Section: Discussionmentioning

confidence: 99%

Plasma Nitriding-Assisted 3D Printing for Die Technology in Digital Micro-Manufacturing

Aizawa¹,

Shiratori²,

Suzuki³

2023

Advances in 3D Printing

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A plasma nitriding-assisted 3D printing method was developed to build up the micro-punch and micro-die systems. Two dimensional punch head and core-die cavity geometries were ink-jet printed or screen-printed onto the AISI316 and SKD11 tool substrate surfaces in following their two-dimensional computer-aided design (CAD) data. The low-temperature plasma nitriding process was utilized to make nitrogen supersaturation only into the unprinted substrates. The sand-blasting and chemical etching were utilized to mechanically or chemically remove the printed parts from punch and die substrate. As sand-blasted and chemically etched AISI316 and SKD11 punches and core-dies were simply finished and used as a die set for micro-embossing, micro-piercing and micro-punching processes. In particular, a micro-pump was selected as a miniature mechanical element. Its 3D CAD geometry was sliced to 2D CAD data for each functional AISI304 stainless steel sheet. A pair of punch and die for each 2D CAD geometry for constituent sheet was prepared by the plasma nitriding-assisted 3D printing. Each sheet was punched out by using this set of punch and die to functionalize each sheet unit in correspondence to the sliced CAD data. These constituent sheets were assembled and joined to a structural unit of micro-pump.

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“…Figure 8 depicts the phase mapping, the KAM distribution, and IPF profile on the cross-section of nitrided AISI316 at 623 K. As had been discussed in [22,23,25], most of the microstructure above NFE at the depth of 30 μm from the surface has two-phase structure, high plastic strains, and fine grain structure. Due to relatively homogeneous nitrogen supersaturation, the plastic straining and microstructure refinement processes co-work with the nitrogen supersaturation and zoneboundary diffusion processes.…”

Section: Mesoscopic Characterization On the Plasma Nitrided Aisi316mentioning

confidence: 91%

Nitrogen Supersaturation of AISI316 Base Stainless Steels at 673 K and 623 K for Hardening and Microstructure Control

Aizawa¹,

Shiratori²,

Yoshino³

et al. 2022

Stainless Steels

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The high-density plasma nitriding at 673 K and 623 K was employed to make 10% of nitrogen supersaturation on AISI316 base austenitic stainless steels. The processing parameters and nitrogen-hydrogen gas flow ratio were optimized to increase the yield of N2+ ion and NH-radical for efficient nitriding. The nitrided AISI316 specimens were prepared for multidimensional analysis to describe the fundamental features of low-temperature plasma nitriding. First, macroscopic evaluation revealed that nitrogen supersaturation induced the γ-lattice expansion and the higher nitrogen content than 4% of mass in depth. The mesoscopic analysis describes the holding temperature and initial grain-size effects on the microstructure changes. Plastic straining, grain-size refinement, and nitrogen zone-boundary diffusion processes advance with nitrogen supersaturation to drive the inner nitriding behavior. The microscopic analysis explains the microstructure refinement, the two-phase structuring, and the microstructure modification. Through this multi-dimensional analysis, the essential characteristics of the low-temperature plasma nitriding of 316 austenitic stainless steels were precisely understood to extend the engineering treatise on the bulk nitrogen stainless steels for surface modification and treatment of stainless steels by nitriding. This plasma nitriding was applied to strengthen and harden the AISI316 wire surfaces toward its application on surgery wires.

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Micro-/Nano-Structuring in Stainless Steels by Metal Forming and Materials Processing

Cited by 7 publications

References 30 publications

Quantitative Characterization of the Affected Zones in a Single Crystal Fe-6Si Steel Sheet by Fine Piercing

Quantitative Characterization of the Affected Zones in a Single Crystal Fe-6Si Steel Sheet by Fine Piercing

Plasma Nitriding-Assisted 3D Printing for Die Technology in Digital Micro-Manufacturing

Nitrogen Supersaturation of AISI316 Base Stainless Steels at 673 K and 623 K for Hardening and Microstructure Control

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