• Title/Summary/Keyword: AISI 4140

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An analytical Machining models based on Flow Stress Properties for Non-Heat Treated and Heat Treated AISI 4140 Steel (열처리 및 비 열처리 AISI4140강의 유동응력 물성치를 기초로 하는 해석적 가공 모델 연구)

  • Lee, Tae-Hong
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.4
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    • pp.419-426
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    • 2011
  • In this study, an experimental and theoretical program were carried out to determine the cutting forces and chip formation at different cutting speeds using a 0.4mm nose radius ceramic insert and -7 rake angle for non heat-treated AISI 4140 (27HRc) and heat-treated AISI 4140 (45 HRc) steel. The results obtained were compared to show the hardness differences between the materials. The secondary deformation zone thicknesses when comparing the two materials show different physical structure but similar size. These results were also discussed in light of the heat treatment and the effects it had on the machining characteristics of the material. In addition, the Oxley Machining Theory was used to predict the cutting forces for these materials and a comparison made. The predicted cutting performances were verified experimentally and showed good agreement with experimental data.

Recrystallization Controlled Deformation of AISI 4140 (AISI 4140 강재의 재결정 제어변형)

  • 조범호
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.135-139
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    • 1999
  • The static softening behavior of AISI 4140 could be characterized by the hot torsion test in the temperature ranges of 10$0^{\circ}C$~120$0^{\circ}C$ and strain rate ranges of 0.05/sec~5/sec. Deformation efficiency which was based on dynamic materials model was calculated from flow stress curves obtained continuous deformation. Interrupted deformation was performed with 2 pass deformation in the pass strain ranges of 0.25{{{{ epsilon _p}}}} ~3{{{{ epsilon _p}}}} and interrupted time ranges of 0.5~100sec. The dependences of process variables pass strain ({{{{ epsilon _i}}}}) stain rate ({{{{ {. } atop {$\varepsilon$ } }}}}) temperature (T) and interpass time ({{{{ {t }_{i } }}}}) on static recrystallization (SRX) and metadynamic recrystallization .(MDRX) could be indicidually predicted from the modified Avrami's equations. Comparison of the softening kinetics between MDRX and SRX showed that the rate of MDRX was more rapid than that of SRX for the same deformation variables. Controlled multipass deformations were performed using deformation efficiency static and metadynamic recrystallization of AISI 4140.

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Wear Characteristics of CBN Tools on Hard Turning of AISI 4140 (고경도강(AISI 4140, HrC60)의 하드터닝에서 가공속도 및 윤활조건 변경에 따른 CBN 공구의 마모 특성)

  • Yang, Gi-Dong;Park, Kyung-Hee;Lee, Myung-Gyu;Lee, Dong Yoon
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.9
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    • pp.799-804
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    • 2014
  • Hard turning is a machining process for hardened materials with high surface quality so that grinding process can be eliminated. Therefore, the hard turning is capable of reducing machining time and improving productivity. In this study, hardened AISI4140 (high-carbon chromium steel) that has excellent yield strength, toughness and wear resistance was finish turned using CBN tools. Wear characteristics of CBN tool was analyzed in dry and MQL mixed with nano-particle (Nano-MQL). The dominant fracture mechanism of CBN tool is diffusion and dissolution wear on the rake surface resulting in thinner cutting edge. Abrasive wear by hard inclusion in AISI4140 was dominant on the flank surface. Nano-MQL reduced tool wear comparing with the dry machining but chip evacuation should be considered. A cryogenically treated tool showed promising result in tool wear.

Surface and Tribological Characteristics of Air-cooled and Oil-cooled AISI 4140 Steel (냉각공정에 따른 AISI 4140 강의 표면 및 트라이볼로지 특성)

  • Cho, Hak-Rae;Lee, Sang Don;Son, Jung Ho;Chung, Koo-Hyun
    • Tribology and Lubricants
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    • v.32 no.5
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    • pp.160-165
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    • 2016
  • AISI 4140 steel is widely used in various mechanical components owing to its superior mechanical properties. Surface hardening techniques are often used to further improve the properties, particularly for applications with moving components. The aim of this research is to understand the effect of heat treatment process on surface properties and tribological characteristics of AISI 4140 steel. In this work, we prepare two different AISI 4140 steel specimens- one cooled by air and one by oil- and determine surface properties such as surface topography and roughness using a confocal microscope. We also observe the cross-sections of the specimens using a scanning electron microscope to understand the difference in the material structure. In addition, we assess the hardness with respect to the distance from the surface using a micro-Vickers hardness tester. After characterizing the surfaces of the specimens, we investigate the wear characteristics of the specimens under hydrodynamic lubrication. The results show the presence of grooves on the surface of the oil-cooled specimens. It is likely that such grooves are formed during the cooling process using the oil. However, we observe no other significant differences in the surface properties of the specimens. The wear test results show the occurrence of severe wear on the oil-cooled specimens, which may be due to the groove formed on the surface. The results of this work may be helpful to improve surface properties using surface hardening techniques from a tribological perspective.

Tribological Properties and Friction Coefficient Prediction Model of 200μm Surfaces Micro-Textured on AISI 4140 in Soybean Crusher (콩 분쇄기의 AISI 4140에서 200μm 미세 패턴 표면의 마찰 계수 및 마찰 계수 예측 모델)

  • Choi, Wonsik;Pratama, Pandu Sandi;Supeno, Destiani;Byun, Jaeyoung;Lee, Ensuk;Woo, Jihee;Yang, Jiung;Keefe, Dimas Harris Sean;Chrysta, Maynanda Brigita;Okechukwu, Nicholas Nnaemeka;Lee, Kangsam
    • Journal of the Korean Society of Industry Convergence
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    • v.21 no.5
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    • pp.247-255
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    • 2018
  • In this research, the effect of normal load, sliding velocity, and texture density on thefriction coefficient of surfaces micro-textured on AISI 4140 under paraffin oil lubrication were investigated. The predicted tribological behavior by numerical calculation can be serves as guidance for the designer during the machine development stage. Therefore, in this research friction coefficient prediction model based on response surface methodology (RSM), support vector machine (SVM), and artificial neural network (ANN) were developed. The experimental result shows that the variation of load, speed and texture density were influence the friction coefficient. The RSM, ANN and SVM model was successfully developed based on the experimental data. The ANN model can effectively predict the tribological characteristics of micro-textured AISI 4140 in paraffin oil lubrication condition compare to RSM and SVM.

Brazing of TiAl and AISI4140 steel using an Ag-Cu-Ti insert metal (Ag-Cu-Ti삽입금속을 이용한 TiAl과 AISI4140 강의 브레이징)

  • 구자명;이원배;김명균;김대업;김영직;정승부
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.45-47
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    • 2004
  • We have investigated the microstructures and the mechanical properties of TiA1/Cerameti1721 (Ag-Cu-Ti insert metal)/AISI4140 joints at 800$^{\circ}C$ for 60 to 300s using induction brazing method. Two continuous reaction layers of AICuTi and AICu$_2$Ti were formed at the interface between the braze and TiAl, whose thickness increased with the brazing time. The braze consisted of Ag-rich, Ti-rich, CuTi and CuTi$_2$ phases. The maximum tensile strength achieved 296MPa, which was 71% of that of TiAl base metal, for the specimen bonded at 800$^{\circ}C$. Further increase of the brazing temperature and time resulted in constant deterioration of its bonding strength due to large amount of brittle IMC.

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The Mechanical Properties of The Compound Layer of Nitrided AISI 4140 Using a PECVD (PECVD를 이용하여 질화된 AISI4140의 화합물층 유무에 따른 기계적 특성 연구)

  • Jeong, Yeon-Ju;Park, Hyeon-Jun;Kim, Hyeong-Sun;Mun, Gyeong-Il
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.05a
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    • pp.75-75
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    • 2015
  • 산업이 발달되고 제품이 소형화 및 고품질화됨에 따라 그에 따른 제품의 품질 조절이 용이하고 자동화하기 쉬울 뿐만 아니라 공해문제 및 후가공 문제 등이 없는 이온질화 열처리 기술의 보급이 급속도로 확산되고 있다. 특히 플라즈마 이온질화는 가스조성, 처리온도, 질화시간, 가스압력 및 인가전류를 조절함으로써 질화층은 물론 화합물의 상을 용이하게 조절할 수 있다. 위와 같은 변수들을 조절함으로써 PECVD 장비에서 DC pulse power를 사용하여 플라즈마 질화법으로 질화처리하였으며 AISI4140강에서 화합물층의 유무에 따른 기계적인 특성을 비교 조사하고자 하였다.

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Constitutive Relation of Alloy Steels at High Temperatures

  • Lee, Young-Seog
    • International Journal of Precision Engineering and Manufacturing
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    • v.6 no.4
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    • pp.55-59
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    • 2005
  • This paper presents a feasibility study whether Shida's constitutive equation being widely used for plain carbon steel in steel manufacturing industry can be extended to alloy steels with a due carbon equivalent model. T,he constitutive relation of the alloy steels (SAE9254, AISI52100 and AISI4140) is measured using hot deformation simulator (GLEEBLE 3500C) at high temperatures ($800^{\circ}C{\~}1000^{\circ}C$) within strain rates of $0.05{\~}40\;s^{-1}$. It has been found the predicted flow stress behavior (constitutive relation) of AISI52100 steel is in agreement with the measured one. On the other hand, the measured flow stress behavior of SAE9254 and AISI4140 steel partly concords with the predicted one when material experiences relatively high strain rate ($10{\~}40\;s^{-1}$) deformation at low temperature ($800^{\circ}C$). It can be deduced that, for AISI52100 steel, Shida's equation with the carbon equivalent model can be applicable directly to the roughing and intermediate finishing stand in hot rolling process for calculating the roll force and torque.

A Study on the Residual Stress of AISI 4140 Formed during Surface Hardening Treatment by using the CO2 Laser Beam (CO2레이저 비임을 이용한 표면경화 처리중 형성된 AISI 4140의 잔류응력에 관한 연구)

  • Park, K.W.;Lee, J.B.;Han, Y.H.;Lee, S.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.9 no.4
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    • pp.289-299
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    • 1996
  • This study has been performed to investigate into some effects of power density and traverse speed of laser beam on the microstructure, hardness and residual stress of AISI 4140 treated by laser surface hardening technique. Optical micrograph has shown that large martensite and a small amount of retained austenite in outermost surface layer and fine lath martensite in inner surface hardened layer are formed under the condition of a given power density and traverse speed. Hardness measurements have revealed that as the power density increases at a given 2.0m/min of the traverse speed, the maximum hardness values of outermost surface hardened layer is increased from Hv=635 to Hv=670. X-ray analysis for residual stress has exhibited that low compressive residual stress values are obtained in center point of the cress section of surface hardened layer with in mid point between the edge and the center point, about 1.5mm from the center point, due simply to a difference in self-quenching rate. It has been shown that the higher the power density at a given traverse speed and the olwer the traverse speed at a given power density, the more the compressive residual stress values are increased due to an increase in the input heat of laser beam.

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