• Metals and materials international
• /
• v.24 no.6
• /
• pp.1202-1212
• /
• 2018

The effects of Nickle (Ni) addition on bainitic transformation and property of ultrahigh strength bainitic steels are investigated by three austempering processes. The results indicate that Ni addition hinders the isothermal bainite transformation kinetics, and decreases the volume fraction of bainite due to the decrease of chemical driving force for nucleation and growth of bainite transformation. Moreover, the product of tensile strength and total elongation (PSE) of high carbon bainitic steels decreases with Ni addition at higher austempering temperatures (220 and $250^{\circ}C$), while it shows no significant difference at lower austempering temperature ($200^{\circ}C$). For the same steel (Ni-free or Ni-added steel), the amounts of bainite and RA firstly increase and then decrease with the increase of the austempering temperature, resulting in the highest PSE in the sample austempered at temperature of $220^{\circ}C$. In addition, the effects of austempering time on bainite amount and property of high carbon bainitic steels are also analyzed. It indicates that in a given transformation time range of 30 h, more volume of bainite and better mechanical property in high carbon bainitic steels can be obtained by increasing the isothermal transformation time.

• Journal of Korea Foundry Society
• /
• v.17 no.6
• /
• pp.569-576
• /
• 1997

Coating materials for Evaporative Pattern Casting (EPC) process have been developed to investigate the effect of refractories on coating material properties. Three types of developed and one foreign coating materials were used. The former designated as A, B, C and the latter named S.K. The refractory of coating material A is spherical shape of zirconia, and the ones of B, C and S.K. is flake shape of mica. Strength, permeability at room and elevated temperature, anti-sand attachability and carbon residuary were evaluated at each coating materials. Permeability measurement device for elevated temperature was also designed. The zirconia type of coating material had excellent permeability, on the other hand the mica type had good strength and anti-sand attachability. It was found that the refractories were not broken during casting, so permeability indicated same trend at both room and elevated temperature. Based on results, coating material contained small size of mica which is designated as B has the best combination for cast iron.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.10a
• /
• pp.56-57
• /
• 2016

Recently amongst Korea's construction companies there has been heightened interest in environment load reduction and resource recycling. As a result, the construction industry is examining recycled materials alternative to cement and blast-furnace slag (BS henceforth) cement, such as waste refractories and desulfurized plaster. This study analyzes the liquidity and intensity characteristics of mortar according to changes in replacement ratios of waste refractories and desulfurized plaster, used as industry by-products in mortar environments that use BS 3-type cements and circulated fine aggregate. As a result, the greater the increase in replacement ratios of desulfurized plaster, the greater the increase in liquidity and air quantity, as well as compression strength.

• Journal of the Korean Professional Engineers Association
• /
• v.20 no.1
• /
• pp.38-43
• /
• 1987

• Journal of the Korean Professional Engineers Association
• /
• v.20 no.2
• /
• pp.16-24
• /
• 1987

• Journal of Korea Foundry Society
• /
• v.4 no.4
• /
• pp.48-51
• /
• 1984

• Journal of the Korean Professional Engineers Association
• /
• v.2 no.6_7
• /
• pp.52-53
• /
• 1969

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.16.2-16
• /
• 2003

• The Korean Journal of Ceramics
• /
• v.6 no.2
• /
• pp.143-149
• /
• 2000

Monolithic refractory technology has been developed for RH vessels, with the purpose of reducing the total refractory cost. The technology includes the use of an improved monolithic refractory and microwave drying. The improved monolithic refractory was an alumina-spinel composition, of the type used in steel ladles, to which fine alumina was added to increase the density and corrosion resistance. The microwave drying method, previously developed and used to dry the monolithic lining in steel ladles, was modified for use in drying the dense, 500mm thick lining in RH vessels. This work has resulted in significant cost savings.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.807-812
• /
• 1995

In this study, comparisons were made among three representative methods for predicting compressive forces on the lumbosacral disc: LP-based model, double LP-based model and EMG-assisted model. Two subjects simulated lifting tasks that are normally performed in the refractories industry. In the refractories lifting tasks, vertical and horizontal distance, and weight of load were varied. To calculate the L5/Sl compressive forces, EMG signals from six trunk muscles were measured and postural data were recorded using the Motion Analysis System. The EMG-assisted model was shown to reflect well all three factors considered here. On the other hand, the compressive forces of the two LP-based models were only significantly affected by weight of load.