• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.519-526
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• 2017

In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.739-746
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• 2014

The objective of this test series was to determine shear load per unit length which causes a unit slip in the fastener joint. The shear load is one of major factors which reflect partial composite action for cold-formed steel wall stud panels. Test method used were based on the methods presented in the 1962 AISI Specification. According to the comparison with experimental strength, it is seen that the shear loads used in nominal axial strength predictions made acceptable results.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.224-229
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• 2010

During the multi-pass wire drawing process, wires suffer a great amount of plastic deformation that is through the cross-section. This generates tensile residual stress at surface of drawn wires. The generated residual stress on surface is one of the problems for quality of wires so that prediction and reduction of residual stresses is important to avoid unexpected fracture. Therefore, in this study, the effect of process variables such as semi-die angle, bearing length and reduction ratio on the residual stress was evaluated through Finite Element Analysis. Based on the results of the Analysis, a prediction model was established for predicting residual stress on the surface of high carbon steel(AISI1072, AISI1082). To identify the effectiveness of the proposed model, X-ray diffraction is used to measure the residual stresses on the surface. As the result of the comparison between calculated residual stresses and measured residual stresses, the model could be used to predict residual stresses in cold drawn wire.

• Journal of Welding and Joining
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• v.33 no.1
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• pp.41-48
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• 2015

In this study, the effect of heat input on weld metal microstructure and the effects of dissimilar weld heat affected zone in quenched and tempered ASTM A517 on the stainless steel AISI 316L is investigated through the optimization of welding parameters. For this purpose, two welding techniques are used, tungsten-conventional gas and pulsed gas with weld wire ER 309MoL with Diameter 2.4 mm. Research showed that the grain size of the heat affected zone in pulsed welding is less compared with conventional welding; weld metal structure is fully austenitic, it has a finer structure in the pulsed method. Additionally, the growth of weld metal adjacent steel A517 is different from steel 316L. Further, investigation showed that the rate of dilution is less in the pulsed method and the impact energy is increased in each three regions of the weld metal and heat affected zones in the pulsed method; the fracture in the weld metal and heat affected zone of steel 316L is quite soft and it is semi-crispy in the heat affected zone of steel A517.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.1
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• pp.19-26
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• 1996

Melt-quenching of steels leads to various metallographic effects such as refinement of grain size, extension of the solid solubility of carbon and alloying elements, and is expected to improve the mechanical properties of conventional steels. Furthermore, this technique is a useful method for producing sheet directly from liquid state. And it will lend itself to development as a continuous cast process which offers significant savings in energy and product costs. The purpose of this study is to present the microstructures of melt-quenched austenitic stainless steels. As the results of this study, the morphology of melt-quenched microstructure show that the roll contact area is columnar structure, and the free surface area is dendrite structure. As the line speed increases, the ratio of $d_{colunnar}/d_{total}$ increases from 0.12 to 0.60, but the ribbon thickness decreases from $150{\mu}m$ to $30{\mu}m$.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.179-187
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• 2015

This study presents the experimental results of the Friction Stir Welding (FSW) of AA6063 aluminum alloy and AISI304 stainless steel butt joint by varying the welding parameters such as the rotating speed and the welding speed. The main results are as follows. The variation of the welding parameters produced various characteristic interfaces and had distinct influences on the joint properties. Increasing the rotating speed and the welding speed decreased the joint tensile strength because it produced the defect on the joint interface. The optimum welding parameter that could produce the sound joint was a rotating speed of 750 rpm and the welding speed of 102 mm/min with the tensile strength of 71 MPa.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.451-458
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• 1993

Wear resistant titanium nirridc(TiN) coatings Were depositecd onto bearing stcel(AISI 52100) by plasma assisted chemical vapor deposition using the gaseous mixtyre of $TiCI_4, N_2, H_2$ and Ar. The In- fluences of the choorine on the crystallinity, microhardness, adhesion. Wear. property of coatings were studied. It was found that the TiN coatings had an outstanding resistance to wear but the mechanical properties of the coatings deteriorated with the increase in the chlorine content. From wear test, many cracks in the trailing edge which was under tensile stress was investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.157-163
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• 2006

This paper described the process of improving durability performance of the exhaust decoupler by the plasma nitriding. The properties of plasma nitriding treatment of AIS1304 stainless steel were tested using specimens before applying plasma nitriding to a mesh ring. In order to analyses the effect of plasma nitriding treatment on the mechanical properties, SEM(Scanning Electron Microscopes), roughness and hardness tester were used. Based on specimen plasma nitriding, we could find appropriate condition for application to the mesh ring of decoupler. To confirm the improved durability performance, we compared the number of cycles, which reaches to fracture, of the nitrided decoupler and that of the unnitrided decoupler by the bending cyclic test. In this test, the durability and wear resistance of the mesh ring are significantly improved by plasma nitriding treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.40-40
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• 1999

가속기나 토카막과 같은 거대한 진공 장치의 용기 내벽을 청정화 하기 위해서는 용기 전체의 열처리(굽기, Baking)와 글로우 방전(Glow discharge) 법을 병행하여 사용한다. Baking은 일반 기체(N2, O2, 그리고 CO2)와 물(H2O)의 탈착에 효과적이고, Glow discharge cleaning은 탄소(Carbon-based)와 산소(Oxygen-based) 화합물의 탈착에 효과적이다. 특히 Glow discharge cleaning의 경우에는 전극의 모양, 진공 용기의 재질과 모양, 전극간의 거리, 사용되는 반응 기체의 압력 등에 따라 그 효과에 큰 차이가 있으므로 다각적인 연구가 필요하다. 본 연구에서는 그림 1과 같이 시험용 스테인레스(AISI 304와 AISI 316LN) 진공 용기를 설치하고, 시험 용기의 한쪽은 배기 용기와 oriffice로, 다른 편은 불순물의 정성.정량 분석을 위해 RGA(Residual gas analyser) 용기와 oriffice로 연결하였다. 전체 시스템 중에서 배기 부분과 분석 부분은 15$0^{\circ}C$에서 24시간 가열하여 전체의 기저 진공도를 1$\times$10-8Torr로 하였다. 기저 진공도의 용기에 고순도의 반응기체 (He, Ar, Ar+He, Ar+H2, Ar+N2 등)를 주입한후, DC 전압(0.8~1.5kV)을 변화하며 글로우 방전의 최적조건을 찾았다. 방전 동안 시험용 용기에서 방출되는 반응 기체 이외의 기체를 RGA로 측정하였고 외부에 Thermocouple을 여러곳에 장착하여 온도 변화를 측정하였다. 이상의 결과로부터 진공 용기 표면적으로부터의 불순물 탈착(desorption)과 불순물 분석, 플라즈마와 내벽의 상호작용등에 대한 결론을 얻을 수 있었다. 또한 Baking과 Glow discharge cleaning을 동시에 수행하여 Baking 온도의 낮춤에 따른 영향 평가도 수행하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.5-15
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• 2007

A welding structures is generally composed of dissimilar steel materials in order to reduce weight cost, and has a gap to fill the welding agent. Also, heat flow analysis should be fulfilled for structure existing of gap to figure out residual stress which is generated after welding. Since mechanical properties of welding structure composed of dissimilar steel is more fragile than mechanical properties of welding structure consisted of same material, heat flow analysis verifying this should be fulfilled as well. Therefore, on this research, heat flow analysis about dissimilar steel weldment consisted of gap existing AISI304 and AISI630 is practiced so that it could be a basic data of research about mechanical properties of gap existing dissimilar steel welding part which is going to be studied later on. During heat flow analysis, heat input model which based on Gaussian profile and using volume heat flux was newly consisted and applied. In addition, for verifying of analysis on this research, gap existing dissimilar steel weldment which had gap of 0.25mm and was welded using Nd-YAG. The welding profile and temperature distribution for weldment during welding was compared to the result which was gotten through heat flow analysis. Both of those results corresponded each other.