• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.142-145
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• 2008

Process simulation requires accurate and reliable data for a wide variety of material properties, ranging from thermal conductivity to flow stress curves. Traditionally such data are gathered from experimental sources, which has significant disadvantages in that not all of the required data is readily available, it may be from various sources that are themselves inconsistent, measurement of high temperature properties is expensive, and furthermore the properties can be sensitive to microstructure as well as to alloy composition. This article describes the development of a new multi-platform software program called JMatPro, which is based on CALPHAD methodology, for calculating the properties and behavior of multi-component alloys. A feature of the JMatPro is that the calculations are based on sound physical principles rather than purely statistical methods. Thus, many of the shortcomings of methods such as regression analysis can be overcome.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.61-66
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• 2010

A virtual manufacturing system that is composed of JMatPro, a material modeler and $DEFORM^{TM}$-HT, a finite element package is applied to the hot press forming process: high temperature material properties for each phase such as flow stress, elastic modulus, Poisson's ratio, thermal expansion coefficient, in addition to TTT curve are predicted by JMatPro and taken into $DEFORM^{TM}$-HT to predict the material behavior considering phase transformation and heat transfer simultaneously. In order to verify the accuracy of computation, the residual stress and the springback were compared with the experimental measurements. Both the predicted and measured principal residual stresses and amount of springback were in good agreement. It was also found that the residual stresses generated from hot press forming are not negligible as it has been generally assumed, although the springback deformation is quite small.

• 소성∙가공
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• 제17권4호
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• pp.249-256
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• 2008

Combined phase transformation and heat transfer was considered on the simulation of hot press forming process, using material properties modeler, $JMatPro^{(R)}$ and a finite element package, $DEFORM^{TM}$-HT. In order to obtain high temperature mechanical properties and flow curves for different phases, a material properties modeler, $JMatPro^{(R)}$ was used, avoiding expensive and extensive high temperature materials tests. The results successfully show that the strength of hot press forming parts may exhibit different strength in the same parts, depending on the contact of blank with tooling. It was also shown effectively that the strength of the parts can be controlled by designing appropriate cooling paths and coolants. This was shown in terms of different heat convection coefficient in the calculation. Overall, current combination of software was shown to be an effective tool for the tool and process design of hot forming process, although the material modeler needs to be additionally verified by an appropriate set of high temperature materials test.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.493-496
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• 2008

The residual stress generated in the boron steel blank formed via hot press forming process was predicted by JMatPro, a material property modeler, and Abaqus. The numerical predictions were compared by the experimental measurements obtained by the instrumented indentation. Both the predicted and measured principal stresses monitored at the outer surface of central bending position were qualitatively in good agreement. It was concluded that the residual stresses generated from hot forming process is not negligible as it has been generally assumed, although the spring back deformation is quite small. This should be specially considered from the part design stage since the tensile nature of the residual stress exhibited on the surface may lead to the stress corrosion cracking.

• 소성∙가공
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• 제18권3호
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• pp.236-244
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• 2009

In response to growing environmental and collision-safety concerns, the automotive industry has gradually used high-strength and ultla-high-strength steels to reduce the weight of automobiles. In order to overcome inherent process disadvantages of these materials such as poor formability and high springback at room temperature, hot forming has recently been developed and adopted to produce some important structural parts in automobiles. This method enables manufacturing of components with complex geometric shapes with minimal springback. In addition, a quenching process may enhance the material strength by more than two times. This paper investigates mechanical and forming characteristics of high-strength boron-alloyed steel with hot forming, in terms of hardness, microstructure, residual stress, and springback. In order to compare with experimental results, a finite element analysis of hot forming process coupled with phase transformation and heat transfer was carried out using DEFORM-3D V6.1 and also, to predict high temperature mechanical properties and flow curves for different phases, a material properties modeler, JMatPro was used.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.731-732
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• 2012

• 한국주조공학회지
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• 제43권6호
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• pp.286-293
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• 2023

본 연구에서는 고강도 Al-Mg-Zn계 알루미늄 합금 연속주조 빌렛의 균질화처리 과정 중 미세조직 전개과정을 다양한 장비(OM, SEM, EDS, DSC)로 분석 및 고찰하였다. 우선, 연속주조된 알루미늄 합금 빌렛 내 입계 및 입내에는 AlMgZn, AlMgFe 및 AlMgZnSi상 등 많은 양이 불균일하게 존재하며, 이들 상은 균질화처리 과정 중 입계 및 기지로 용해된다. 합금설계 프로그램 및 동력학 방정식을 활용한 결정립 내 주요 합금원소인 Mg 및 Zn의 확산거동을 분석한 결과, JMatPro 내 균질화처리 모드에서 대상합금 내 Mg이 Zn 대비 기지 내로 빠르게 용해되나, 동력학 방정식의 경우에도 유사한 경향성이 나타난다. 확산속도에 대한 의미로 실제로 Zn 대비 상대적으로 Mg이 많은 양을 함유하고 있어 기지로 확산과 동시에 고용되었음을 확인할 수 있었다.

• 소성∙가공
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• 제23권8호
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• pp.475-481
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• 2014

Water quenching is one method of cooling after hot forming, which is presently being used for the manufacturing of automobile parts. The formed parts at room temperature are heated and then cooled rapidly in a water bath to produce high strength. The formed parts may undergo excessive thermal distortion during the water quench. In order to predict the distortion during water quenching, a coupled thermo-mechanical simulation is needed. In the current study, the simulation of heating and cooling of boron steel cylinders was performed. The material properties for the simulation were calculated from JMatPro, and the convective heat transfer coefficient was obtained from experimental tests. The results show that the thermal distortion and the residual stresses are well predicted by the coupled simulation.

• 소성∙가공
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• 제25권4호
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• pp.248-253
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• 2016

Induction hardening process of tubular drive shaft for automobile is simulated by combining the thermal, mechanical, electro-magnetic and metallurgical analysis models. Various material properties for each analysis model are obtained in a consistent way via material properties calculation software, JMatPro^®. To consider the scanning process of induction heating, boundary element method is adopted for electro-magnetic field calculation. The distribution of temperature, stress and phase volume fraction are tracked out through the whole process and the effect of scanning velocity is reviewed. The analysis result shows that the critical principal stress is developed at the phase boundary where martensite is formed.

• 열처리공학회지
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• 제26권3호
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• pp.126-131
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• 2013

In this study, effects of silicon addition on the spheroidizing annealing of hyper-eutectoid steel was investigated. Heat treatment at various temperatures in the ${\gamma}+{\theta}$ region was also conducted in order to systematically control the kinetics of undissolved cementite. It was found that small amount of Si addition could increase both $A_1$ and $A_{cm}$ transformation temperature by both the JMat Pro evaluation and dilatometric measurement. It was also revealed by the microstructural observation that the volume fraction of retained cementite during heat treatment increased with decreasing temperature as well as increasing Si content. Based on the results obtained, it could be suggested that spheroidization at relatively higher temperature above $950^{\circ}C$ could be achieved by small addition of Si.