Changes in Mechanical Properties of WC-Co by Ultrasonic Nanocrystal Surface Modification Technique

이승철,; 김준형,; 김학두,; 최갑수,; 아웨즈한, 아마노프; 편영식,

doi:10.9725/kstle.2015.31.4.157

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…2.1 초음파 나노표면 처리법에 따른 시험편의 분류 (Amanov et al, 2012;Amanov et al, 2014;Lee et al, 2015;Suh et al, 2007).…”

Section: 시험방법과 실험장비unclassified

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Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films

Shim¹,

Suh²,

Kim³

et al. 2018

J. Ocean Eng. Technol.

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In order to accumulate data to lower the friction coefficient of a press mold, tribological tests were performed before and after coating SM45C with a PVC/PO film and plasma coating (CrN, concept). The ultrasonic nanocrystal surface modification (UNSM)-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those of untreated materials. A comparison of the weight change before and after the tribological test with the CrN and the concept coating material and that of the untreated material showed that the wear loss of the concept coating material and P-UNSM treated material (that is, the UNSM treated material treated with the concept coating) showed a tendency to decrease by approximately 55-75%. Concept 100N had a lower friction coefficient of about 0.6, and P-UNSM-30-100N showed almost the same curve as concept 100N and had a low coefficient of friction of about 0.6. The concept multilayer coating had a thickness of 5.32 μm. In the beginning, the coefficient of friction decreased because of the plasma coating, but it started to increase from about 250-300 s. After about 350 s, the coefficient of friction tended to approach the friction coefficient of the SM45C base metal. The SGV-280F film-attached test specimen was slightly pushed back and forth, but the SM45C base material was not exposed due to abrasion. The friction coefficient was 0.22, which was the lowest, and the tribological property was the best in this study.

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“…2.1 초음파 나노표면 처리법에 따른 시험편의 분류 (Amanov et al, 2012;Amanov et al, 2014;Lee et al, 2015;Suh et al, 2007).…”

Section: 시험방법과 실험장비unclassified

“…소재는 현재 STS 304L(오스테나이트계 스테인레스강) 등이 널리 사용되고 있다 (Chun et al, 2009;Kim et al, 2010;Kim et al, 2011Yu et al, 2013;Suh et al, 2016 (Amanov et al, 2012;Amanov et al, 2014;Gim and Jeong, 2007;Jeon et al, 2014;Lee et al, 2015;Pyun et al, 2012;Suh et al, 2016).…”

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Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films

Shim¹,

Suh²,

Kim³

et al. 2018

J. Ocean Eng. Technol.

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“…In addition, many studies have verified that UNSM technology improves the surface roughness, wear resistance, and fatigue strength of metal. Lee et al confirmed the possibility of extending the service lives of press dies through wear tests [22]. Moreover, Cho et al improved the surface characteristics of an aluminum alloy, AlSi10Mg, produced by direct metal laser sintering through the application of UNSM, and Kheradmandfard et al utilized UNSM to improve the surface hardness of the titanium-niobium-tantalum-zirconium alloy [1,23].…”

Section: Introductionmentioning

confidence: 99%

Method of ultrasonic nano-crystal surface modification for improvement of surface characteristics of AISI D2 heat-treated with different tempering conditions

Cho

Shim

2022

Int J Adv Manuf Technol

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AISI D2, an alloy tool steel, has been widely used as a cold-work die steel because of its excellent wear resistance, toughness, and machinability. However, when it is used as a mold or tool under a high load, high hardness and wear resistance are required to improve its service life. This study aimed to apply ultrasonic nanocrystal surface modification (UNSM), a local surface hardening technology, to the surface of D2 steel. To maximize the surface improvement effect achievable through UNSM, it is important to select the optimal process conditions according to the characteristics of the base metal.Therefore, the effects of UNSM were compared for different initial hardness values of D2 in this study.To this end, the base metal was subjected to different heat treatment conditions to exhibit different hardness values (approximately 40, 45, 50, and 55 HRc). Changes in the surface of the base metal were observed according to the three main parameters of the UNSM process: the load, inter-pass interval, and feed rate. No significant changes in the surface roughness and hardness was caused by the feed rate. As the inter-pass interval of UNSM decreased and the static load increased, the surface roughness of the base metal increased. However, the specimen with low initial hardness (D2-H40), the roughness improvement decreased as the load increased. On the other hand, the surface hardness improvement increased as the inter-pass interval decreased and the load increased regardless of the initial hardness of the base metal. It also was found that the specimen with the highest initial hardness (D2-H55) exhibited the greatest hardness improvement rate of 8.7 % and smallest hardened layer thickness of 220 μm. In addition, the largest compressive residual stress (-1,130.6 MPa) was formed on the surface of D2-H55 after UNSM, which occurred because the base metal with high initial hardness had limited plastic flow due to fine grains and low ductility, causing thus the energy repeatedly delivered Method of ultrasonic nanocrystal surface modification for improvement of surface characteristics of AISI D2 heat-treated with different tempering conditions Seung Yeong Cho 1,2 and Do Sik Shim 1,2, by UNSM to be concentrated in a limited area. Consequently, reducing the inter-pass interval is effective on improving the surface roughness and hardness regardless of the material hardness. However, the load must be applied at an appropriate level, depending on the material hardness. Therefore, when D2 is heat-treated and used according to the product requirements, it will be effective to consider the changes after UNSM treatment based on hardness after heat treatment that were derived in this study.

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“…In addition, many studies have verified that UNSM technology improves the surface roughness, wear resistance, and fatigue strength of metal. Lee et al confirmed the possibility of extending the service lives of press dies through wear tests [12]. Moreover, Cho et al improved the surface characteristics of an aluminum alloy, AlSi10Mg, produced by direct metal laser sintering through the application of UNSM, and Kheradmandfard et al utilized UNSM to improve the surface hardness of the titanium-niobium-tantalum-zirconium alloy [13,14].…”

Section: Introductionmentioning

confidence: 99%

Strategy for Surface Post-Processing of AISI 316L Additively Manufactured by Powder Bed Fusion Using Ultrasonic Nanocrystal Surface Modification

Cho

Kim

Pyun

et al. 2021

Metals

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Ultrasonic nanocrystal surface modification (UNSM) technology was applied to the surfaces of specimens additively manufactured by powder bed fusion (PBF). The changes in roughness and hardness due to the UNSM were set as objective functions, and the optimal conditions for the main parameters were derived through the response surface method (RSM) and Box–Behnken design (BBD). Regression analysis-based mathematical models for predicting the surface hardness and roughness are presented and validated. The RSM results show that the surface roughness is highly dependent on the load and ball tip diameter, and the surface roughness significantly improves as the inter-pass interval and ball tip diameter decrease. Through BBD and ANOVA, the optimal conditions for the improvement of surface characteristics were found to be a load of 40 N, inter-pass interval of 10 μm, and ball tip diameter of 2.38 m. The surface treated under these optimal conditions exhibited a hardness of 497 Hv and surface roughness of 1.32 μm, which were significantly improved compared to the values for an untreated specimen. In addition, it was confirmed that the grains are significantly refined after UNSM, and scratch resistance increases for the top layer of the surface directly affected by the UNSM horn.

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Changes in Mechanical Properties of WC-Co by Ultrasonic Nanocrystal Surface Modification Technique

Cited by 5 publications

References 5 publications

Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films

Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films

Method of ultrasonic nano-crystal surface modification for improvement of surface characteristics of AISI D2 heat-treated with different tempering conditions

Strategy for Surface Post-Processing of AISI 316L Additively Manufactured by Powder Bed Fusion Using Ultrasonic Nanocrystal Surface Modification

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