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Volume 73 (2002)
- Issue 4 Pages 221-
- Issue 3 Pages 149-
- Issue 2 Pages 87-
- Issue 1 Pages 5-
Volume 73, Issue 3
Plastic Working
Displaying 1-8 of 8 articles from this issue
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Paper
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Article type: Introduction
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 149-151
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSControlled forging is greatly effective in the weight reduction of automobile components as mentioned in the first report1), because of very fine microstructure. Its fine microstructure can be obtained by the control of forging temperature, strain and cooling rate. Thus, the optimization of the forging process is very important. Process modeling using finite element method (FEM) is very effective for the optimization of forging process, which has been widely used in controlled rolling. In the process modeling of controlled forging, austenite microstructure prediction and ferrite-pearlite microstructure prediction transformed from recrystallized and work-hardened austenite must be discussed respectively. Moreover, it is also necessary to predict yield strength, tensile strength, fatigue strength and ductility for the purpose of weight reduction. However, there are few process modeling systems which satisfy these requirements. In this attempted study, the construction of a process model of controlled forging which can predict the above-mentioned microstructure have been attempted. In the prediction of the austenite microstructure, Sellers' model showed good a result. In the prediction of the ferrite-pearlite microstructure transformed from recrystallized austenite, good results were obtained by using an effective austenite interfacial area. On the other hand, concerning the ferrite-pearlite microstructure transformed from work-hardened austenite, it was confirmed to be predicted precisely by the use of 'effective retained strain' which is newly suggested.View full abstractDownload PDF (191K) -
Article type: Introduction
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 153-160
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSThe techniques of grain size prediction on process design before industrial trials and grain refinement in practice are strongly required for INCONEL super alloy 718 applications. This paper treats the prediction of grain size local distribution of cog forged billets by FE analyses. And in order to estimate the homogeneity of whole length direction analyses are conducted with special regard to the longitudinal section. The experimentally generated microstructure laws organized by both dynamic and static events are incorporated into MSC.Marc FE software package. And four process schedules of single pass cog forging operation combining reduction in height with feeding distance between bites are simulated. The numerical outputs indicates that the grain size is strongly affected by reduction in height. And periodically distribution in grain size and temperature is dominated by feeding distance between bites. Therefore only an increase of deformation can not leads to a uniform microstructure with finer grain. The importance of feeding distance on microstructure control is derived from FE analyses. A fine-grained uniform microstructure will be attained by combining smaller feeding distance with larger reduction in height.View full abstractDownload PDF (360K)
Review
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Article type: technical report
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 169-175
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSTo reduce the development and production lead time, and to make precise parts are main targets in forging industry. With the increasing computational power and the advances in software, development in the finite element modeling of forging processes became more and more realistic. The finite element methods (FEM) are now applicable for not only 2D but also 3D problems. Material flow, forging defects, temperature rise, elastic deformation of tools as coupled problem, tool life, microstructure and mechanical properties of forgings and residual stress and distortion after heat treatment can be predicted using FEM by personal computer. Until recently, the limitation in virtual modeling was given by the capacity of the computers. Consequently users have been forced to reduce their models. But with the permanently increasing computer capacity, the main focus begins to switch back to the problems of the modeling and the determination of the parameter data.View full abstractDownload PDF (469K) -
Article type: technical report
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 177-182
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSFor steel hot rolling, rolling oil plays an indispensable role for the purpose of roll wear control and surface quality of steel product. This review is focus on hot strip mill and shape mill, discussing their history, development in laboratory test method for rolling oil, recent performance requirements from hot rolling and new formulation to cope with those requirements, and new feeding technology.View full abstractDownload PDF (199K) -
Article type: technical report
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 183-188
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSThe trend of hot and warm forging die steels is reviewed. The user's demand for these applications are summarized as cost cutting and short delivery time. To meet these requirements, the demand to die steels becomes more and more severe. As the failure modes of hot and warm forging are wear, heat checking and crack, high hot hardness, heat checking resistance and toughness are required for die steels. DH31-S is one of the high performance hot work die steels and is widely used for forging press dies for automotive parts. Powder metallurgy matrix high speed tool steel, DEX-M1, shows much higher toughness than hot work die steels and is expected to be applied to warm forging dies. For the application where the die surface temperature becomes much higher, Ni-base heat resisting steels such as IN718 and U520 are prospected. To reduce the cost of forging products total consideration is required such as not only die steels but machining, heat treatment, surface modification and forging conditions as well.View full abstractDownload PDF (126K)
Technical Paper
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Article type: scientific monograph
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 189-194
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSThe rolling simulator 'SIMURO-D' was developed to aim at improvement in productivity of wires and rods of workhardable materials and development of a controlled rolling process. This simulator is based on 3D-FEM code 'SIMURO', programmed by Dr. Komori of Daido Institute of Technology. It's characteristic is high-speed calculation in thermo coupled analysis. This simulator can be used for 2-roll rolling, 3-roll rolling, 4-roll rolling, shape steel rolling and cooling zone. By GUI, users calculate easily in multi passes. In this paper, we introduce functions of this simulator and demonstrate calculation of austenite grain diameter.View full abstractDownload PDF (683K) -
Article type: scientific monograph
Subject area: New Material
2002 Volume 73 Issue 3 Pages 195-202
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSIt is well known that to produce titanium clad steel by hot rolling process is quite difficult because of harmful TiC or Ti-Fe type intermetallic compounds layers at the bonded boundary. These harmful layers bring about the decreases of the bonding strength and the quality of joints. These harmful layers are formed by diffusion of the C and Fe elements at high temperature. In order to avoid the formation of them, there are two effective method which are the use of insert metal like Cu, or sometimes Ni, and the decreases of hot rolling and annealing temperature. The method of using insert metal has already confirmed by many researchers, but the method of controlling the productive temperature has not enough yet. This paper shows the systematic experiments on hot rolling and cold rolling process. As a result, the suitable controls of hot rolling and annealing temperatures are confirmed to be quite effective to diminish the harmful layer and to be contributed to improve the quality of bonding.View full abstractDownload PDF (591K) -
Article type: scientific monograph
Subject area: Material Processing
2002 Volume 73 Issue 3 Pages 203-208
Published: 2002
Released on J-STAGE: October 15, 2002
JOURNAL FREE ACCESSWire drawing of Magnesium alloy AZ31 was investigated with emphasis on the reduction of the drawing temperature. It was clarified that the proper heat treatments raised the reduction of area of AZ31, when it improved 57% compared with that of the no heat treated one. The ring compression test was carried out for the four kinds of lubricant, and the best one with the lowest frictional coefficient was selected. The wire drawing was performed and it was found out that the AZ31 wire was able to be drawn even at room temperature by heating a die at more than 170 degrees C. The lowest temperature to obtain the recrystallized grain was 140 degree C.View full abstractDownload PDF (961K)
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