A Study of Multiple Scale FEM Modeling for Prediction of Inner Void Closing Behavior in Open Die Forging Process

Kwak, Euishin; Kang, Gyung-Ju; Lee, K.

doi:10.5228/kstp.2012.21.5.319

Cited by 4 publications

(1 citation statement)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These voids have to be eliminated by an appropriated process like forging to prevent sudden failure of the forged part in operation. Numerous researchers studied the effects of process parameters on void closure behavior during forging to investigate the relationships among process design, process parameters and behavior of the void closure using the low or middle carbon steel [1][2][3][4][5][6]. It was also revealed from numerical anlyses that hydrostatic pressure and effective strain has a strong influence on the void closure [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Crack Formation in Hot Compression Test of Ultrahigh Carbon Steel

Kang

Lim

Lee

2014

KEM

View full text Add to dashboard Cite

Experimental works were carried out to investigate microstructure and crack formation during compression tests of 1.9wt%Cultrahigh carbon steel according to temperature and strain rate. As-received ultrahigh carbon steel is composed of precipitated cementites and pearlite matrix. In addition, numerous voids were observed in the matrix of as-received material. The compression tests at 800oC showed that the voids within the matrix are closed with increase of reduction ratio. On the other hand, when the reduction ratio increased numerous micro-cracks were newly formed in the bulky cementites and at the interfaces between hard cementite and soft matrix. It was also observed that because the volume fraction of cementite is reduced when temperature increased, volume fraction of newly formed micro-crack significantly decreased. Cast microstructures were observed after compression test at 1130oC due to local melting. From experimental results and microstructure anlayses, it was concluded that the forging temperature should be controlled at the temperature of more than 900oC and less than 1130oC.

show abstract

Section: Introductionmentioning

confidence: 99%

Microstructures and Crack Formation in Hot Compression Test of Ultrahigh Carbon Steel

Kang

Lim

Lee

2014

KEM

View full text Add to dashboard Cite

show abstract

Process Design for Manufacturing 1.5wt%C Ultrahigh Carbon Workroll: Void Closure Behavior and Bonding Strength

Lim¹,

Lee²,

Kim³

et al. 2013

Transactions of Materials Processing

View full text Add to dashboard Cite

Experiments and numerical simulations of the incremental upsetting test were carried out to investigate void closure behavior and mechanical characteristic of a 1.5wt%C ultra-high carbon steel. The experimental results showed that the voids become quickly smaller as the reduction ratio increases. The simulation results confirmed this behavior and indicated that the voids were completely closed at a reduction ratio of about 40~45% during incremental upsetting. After the completion of the incremental upsetting tests, the process of diffusion bonding was employed to heal the closed voids in the deformed specimens. To check the appropriate temperature for diffusion bonding, deformed specimens were kept at 800, 900, 1000 and 1100°C for an hour. In order to investigate the effect of holding time for diffusion bonding at 1100°C , specimens were kept at 10, 20, 30, 40, 50 and 60minutes in the furnace. A distinction between closed and healed voids was clearly established using microstructural observations. In addition, subsequent tensile tests demonstrated that complete healing of a closed void was achieved for diffusion bonding temperatures in the range 900 ~ 1100°C with a holding time larger than 1 hour. Key Words

show abstract

Forging of 1.9wt%C Ultrahigh Carbon Workroll : Part I - Analysis on Void Formation and Microstructure

Lim¹,

Lee²,

Kim³

et al. 2013

Transactions of Materials Processing

View full text Add to dashboard Cite

Compression tests were conducted at the various temperatures and strain rates to investigate void formation and microstructures behavior of a 1.9wt%C ultrahigh carbon steel used in forged workrolls. The microstructure, grain size and volume fraction of cementite were determined using specimens deformed in the temperature range from 800 to 1150 o C and strain rates from 0.01 to 10/s. It was found from the microstructural analysis that the grain size is larger at higher temperatures and lower strain rate deformation conditions. In addition, a higher volume fraction of cementite was measured at lower temperatures. The brittle blocky cementite was fractured at 800 o C and 900 o C regardless of strain rate. As a result, numerous new micro voids were formed in the fragmented blocky cementite. It was also found that local melting can occur at temperatures of more than 1130 o C. Therefore, the forging temperature should be controlled between 900 o C and 1120 o C.The temperature rise, which depends on the anvil stroke and velocity, was estimated through cogging simulation to find the appropriate forging temperature and to prevent local melting due to plastic work.

show abstract

A Study of Multiple Scale FEM Modeling for Prediction of Inner Void Closing Behavior in Open Die Forging Process

Cited by 4 publications

References 3 publications

Microstructures and Crack Formation in Hot Compression Test of Ultrahigh Carbon Steel

Microstructures and Crack Formation in Hot Compression Test of Ultrahigh Carbon Steel

Process Design for Manufacturing 1.5wt%C Ultrahigh Carbon Workroll: Void Closure Behavior and Bonding Strength

Forging of 1.9wt%C Ultrahigh Carbon Workroll : Part I - Analysis on Void Formation and Microstructure

Contact Info

Product

Resources

About