High-cycle fatigue properties of fine particle peened Fe-3mass%Si steel sheets
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Effects of heavy peen with fine particles and grain size on both tensile and fatigue properties of Fe-3mass%Si steel sheets have been studied. Fine grain structure resulted in higher tensile strength and 10^7 cycles fatigue one. The fine partical peen increased tensile elongation and fatigue strength. The increase of about 14% in 10^7 cycles fatigue strength by fine partical peening was available for the materials over several ten μm in grain diameter, while there was no big difference for the material with finer grain size. Mobile dislocations in the specimen surface were employed more homogeneous plastic deformation there and resulted in higher resistance against crack generation, since strain incompatibility at grain boundaries due to heterogeneous planer slip causes local stress concentration. Electron backscatter diffraction analyses made clear fatigue damage structures such as plastic deformation in the surface layer, crystal rotation in grains and localied deformation bands in large grains.Fe-3mass%Si鋼薄板の引張特性と疲労特性に及ぼす微粒子ハードピーニングと結晶粒サイズの影響について検討した。結晶粒微細化では引張強度および10＾7回疲労強度の増大が得られた。微粒子ピーニング処理の結果、引張延性と疲労強度が向上した。微粒子ピーニング処理では、結晶粒径が数十μm以上の粗大粒組織において10＾7回疲労強度は14%程度の向上が認められたが、微細粒材では微粒子ピーニングの効果は少なかった。これは、試験片表層に導入した可動転位によってより均一な塑性変形が表層部で得られ、き裂発生的抵抗が高まったためである。なぜならば、不均一な平面的すべりにより粒界に生じるひずみ不整合が局所的応力集中をもたらすからである。EBSD解析的結果、表層部の塑性変形、結晶粒内の方位回転、粗大粒内の変形帯といった疲労損傷が明確となった。
- Vysoka? s?kola ba?n?ska? - Technicka? univerzita Ostrava.の論文
Vysoka? s?kola ba?n?ska? - Technicka? univerzita Ostrava. | 論文
- High-cycle fatigue properties of fine particle peened Fe-3mass%Si steel sheets
- Novel techniques characterizing subsurface fatigue crack generation and crack growth in martensite steels
- Relationship between subsurface fatigue crack generation and strain incompatibility