Evolution of Microstructure from the Surface to the Interior of Cr-Mo Steel by Water Jet Peening

Ijiri, Masataka; Shimonishi, Daichi; Nakagawa, Daisuke; Yoshimura, Toshihiko

doi:10.4236/msa.2017.810050

Cited by 17 publications

(17 citation statements)

References 4 publications

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“…Voids were observed at grain boundaries. They were also observed in the WJC-processed SCM435, and were mainly observed at grain boundaries [3]. No voids or cracks were observed at depths of approximately 2-3 mm from the surface.…”

Section: Experimental Methodsmentioning

confidence: 79%

“…It is considered that this variation in grain growth is affected by high-temperature and high-pressure bubbles colliding with the surface by the cavitation jet. The interior of SCM 435 processed by MFC in our previous report changed from pearlite to spheroidized cementite after processing [3]. It is thus considered that the specimen interior was annealed.…”

Section: Influen Surface To Inmentioning

confidence: 95%

“…Tempering was performed at 580 °C. The specimens were subsequently cut into rectangular specimens with dimensions of 100 × 100 × 3 mm 3 . Fig.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…When the compression force is converted to compression deformation, the deformation returns to its original state after the cavitation collapse; however, if a small amount of plastic deformation occurs, then compressive residual stress is generated after cavitation collapse. We have recently reported that voids and cracks tend to form inside specimens in exchange for a high compressive residual stress with an increase in pressure applied to the specimen surface [3].…”

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confidence: 99%

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Surface Modification of Ni-Cr-Mo Steel by Multifunction Cavitation

Ijiri¹,

Shimonishi²,

Nakagawa³

et al. 2017

JMSE-A

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Abstract:The multifunction cavitation (MFC) technique is referred to as a mechanical-electrochemical cavitation method because it includes both mechanical action by microjets (MJs), with high pressure from water jet cavitation (WJC), and electrochemical action by MJs, with the high-temperature reaction field of ultrasonic cavitation (UC). Recently, when MFC was applied to Cr-Mo (JIS-SCM435) steel, the corrosion resistance and compressive residual stress in rust were improved, and voids and cracks of the specimen interior were suppressed compared to that with WJC. It is of interest whether this phenomenon occurs similarly in other low-alloy steels processed by MFC. In the present study, MFC was applied to the modification of Ni-Cr-Mo steel (JIS-SNCM630) surfaces. SNCM630 processed by MFC exhibited improved corrosion resistance and compressive residual stress in rust, and voids and cracks in the interior were not generated from the specimen surface to any significant extent.

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Section: Experimental Methodsmentioning

confidence: 79%

Section: Influen Surface To Inmentioning

confidence: 95%

“…Tempering was performed at 580 °C. The specimens were subsequently cut into rectangular specimens with dimensions of 100 × 100 × 3 mm 3 . Fig.…”

Section: Experimental Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Surface Modification of Ni-Cr-Mo Steel by Multifunction Cavitation

Ijiri¹,

Shimonishi²,

Nakagawa³

et al. 2017

JMSE-A

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“…0.5 mm in the specimen after WJC processing is considered to be the influence of voids and cracks inside the specimen. Recently, the authors report that voids and cracks tend to form inside the specimen after WJC processing [8]. The hardness in the near-surface region of the WJC-processed SNCM630 was 270 HV.…”

Section: Cav18-05191mentioning

confidence: 99%

Steel Processed by Water Jet Cavitation with Ultrasonic Irradiation

Ijiri¹,

Nakagawa²,

Tanaka³

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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Alloy steels for machine structural is used for industrial equipment. However, the operating environment is often harsh, requiring the development and application of various surface treatments. The authors focus on the use of water jet cavitation (WJC) with ultrasonication. WJC technology enables the generation of high pressure during cavitation collapse near the surface when a water jet ejected from a nozzle impacts a metal surface. This pressure causes a slight deformation in the impacted surface region and introduces a compressive residual stress due to the elastic constraints of the underlying and surrounding metal. If ultrasonic irradiation is applied to WJC bubbles with diameters of several hundred microns, the bubbles are subjected to alternating high and low sound pressures, which leads to a high-pressure and high-temperature reaction field. This technique is referred to as multifunction cavitation (MFC). The authors have reported several characteristics of specimens processed by MFC to date. For example, titanium oxide powder, which is widely used as a photocatalyst, can be fabricated in the form of nanoparticles by MFC. In addition, the indium tin oxide (ITO) film deposited on the transparent electrode mounted on liquid crystal displays can be melted by MFC treatment, leading to the release of indium, which has a low melting point. In present study, the compressive residual stress and corrosion resistance of Cr-Mo and Ni-Cr-Mo steels were improved by MFC treatment. Moreover, the authors compared conventional WJC technology to MFC technology. MFC was found to lead to higher compression residual stresses and higher corrosion resistances compared to conventional WJC. The corrosion resistance was revealed by the formation of an oxide film through selective oxidation and the concomitant reduction of surface defects. The oxide coating formed by a reaction between the dissolved oxygen in water with Cr on the metal surface during processing.

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