• Journal of the Korean Society for Heat Treatment
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• v.10 no.4
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• pp.278-287
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• 1997

The TRIP behavior in tensile deformation of retained austenite formed by reverse transformation treatment in 0.15%C-6%Mn-(Ti, Nb) steels has been investigated. The shape of retained austenite was almost a fine lath type with $0.1{\sim}0.3{\mu}m$ width and the two distinctly different transformation sequences of retained austenite, i) retained austenite${\rightarrow}$martensite and ii) retained austenite${\rightarrow}$deformation twin${\rightarrow}$martensite were revealed. The strength-elongation combination was increased with increasing the holdig time at low temperatures ($625^{\circ}C$) but decreased abruptly with increasing holding time at high temperatures ($675^{\circ}C$), owing to the lowering of ductility. The strength-elongation combination and TRIP effect was lower in tensile deformation in the range of $100{\sim}250^{\circ}C$ than room temperature. The tensile strengh and elongation of a reverse transformed steels with addition of Ti or Nb was 93kg/, 40% respectively, which is higher over 10% of strength without ductility loss than in 0.15%C-6%Mn steels.

• Resources Recycling
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• v.23 no.1
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• pp.70-79
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• 2014

In this study, waste polypropylene and waste ground rubber tire(WGRT) composites were prepared by using a modular intermeshing co-rotating twin screw extruder. The effect of three main factors such as WGRT contents, particle size, compatibilizers on the properties of waste PP/WGRT composites was extensively investigated. Tensile strength of the composites was decreased with an increase in WGRT contents, whereas elongation at break and impact strength were increased. The tensile strength, elongation at break and impact strength of the composites with the smaller size of the WGRT were more enhanced. Addition of PP-g-MA into waste PP/WGRT composites exhibited better tensile strength. However, elongation at break and impact strength were slightly decreased with increasing of PP-g-MA. On the other hand, tensile strength, impact strength and elongation at break of the composites were increased by adding the EPDM-g-MA and SEBS-g-MA. Especially, elongation at break was significantly increased compared to the composite with PP-g-MA.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.559-567
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• 2011

Recently, many researches on high strength reinforcing steel have been conducted to construct optimum reinforced concrete structures. However, the studies have shown that high strength steel shows less elongation capacity than normal strength steel. Therefore, high strength reinforcing steel may not satisfy the minimum elongation requirement of current standards. Moreover, elongation measurements may be not standardized ones since each standard has its own requirements for minimum elongation and gage length. Therefore, the standards for reinforcing steel testing must be investigated to verify the validity of Korean Standard D 3504. This research aimed to compare the requirements for minimum elongation and gage length of the Korean, American, Japanese, European, and ISO Standards. Then, the study further investigated accuracy of the standards by tensile test of reinforcing steel. The study results showed that the Korean Standard has the strictest requirement. Based on the study results, the authors proposed modified minimum elongation requirements for general reinforcing steel and new requirements for seismic reinforcing steel.

• Journal of Technologic Dentistry
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• v.14 no.1
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• pp.119-132
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• 1992

This paper aims to investigate the effect of B and Si upon the mechanical properties, microstructure and corrosion resistance of Co-Cr base alloy. Ten groups of alloy ingot ingot with various contents of B and Si were remelted by high frequency electrical induction furnace and cast into tensile specimen of ADA Specification No. 14 Tensile and hardness test were carried out by Amsler and Rockwell hardness tester(R-30N), respectively. The microstructures of specimen were observed by SEM. The results obtained are summarized as follows : 1. As B content is increased, tensile strength, yield strength and Rockwell hardness number(R-30N) are also increased significantly, while the elongation is decreased significantly. 2. As Si contect os increased, no significant chang in tensile strength is noticed, yield strength is slightly decreased, but Rockwell hardness number(R-30N) is moderately in creased, Elongation marks maxium value with 1% Si content while with more than 1% Si it is decreased. 3. As B content is increased corrosion resistance is decreased and is at best with 1.5% B content. Corrosion resistance is increased with the increase of Si content and the alloys with Si over 3.0% showed corrosion resistance. 4. As B content increased, precipitates are increased in number at grain boundaries. The grain size tends to become coarse with the increase of Si content. 5. Co rich-Cr alloy is present through matrix whereas at the grain boundaries Cr base precipitates are primarily formed.

• Korean Journal of Materials Research
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• v.21 no.6
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• pp.303-308
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• 2011

The effect of heat treatment on the micro-structures and the mechanical properties of 0.002% boron added low carbon steel was investigated. The tensile strength reached the peak at about $880-890^{\circ}C$ with the rising quenching temperature and then the hardness decreased sharply, but the tensile strength hardly decreased. The tensile and yield strength decreased and the total elongation increased with a rising tempering temperature, but the tensile and yield strength sharply fell and the total elongation prominently increased from above a $400-450^{\circ}C$ tempering temperature. Tempered martensite embrittlement (TME) was observed at tempering condition of $350-400^{\circ}C$. In the condition of quenching at $890^{\circ}C$ and tempering at $350^{\circ}C$, the boron precipitates were observed as Fe-C-B and BN together. The hardness decreased in proportion to the tempering temperature untill $350^{\circ}C$ and dropped sharply above $400^{\circ}C$ regardless of the quenching temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.163-168
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• 2001

This study examinated the application in construction field and the development of waterproofing material system by the spray water-soluble rubber asphalt to solve the problems of synthetic polymer sheet and gio membrane(A mat sheet of Bentonite) that had been used domestic waterproofing material in advance. As the result of study, characters of study water-souble rubber asphalt are the follows; 1) The amount of water absorption was '0.06'g and the seepage quantity was '0'g in result. 2) The tensile strength was about 30.7kgf/$cm^2$ and the elongation was about 72.4% in result. 3) After reliance of temperature test had been ended, the tensile strength was about 72.4kg/$cm^2$ in low temperature and about 30.7kgf/$cm^2$ in normal temperature. 4) After acid and alkaline treatment had been ended, the tensile strength was about 19.7kgf/$cm^2$ and about 21.9kgf/$cm^2$ in result. 5) After chlorine ion treatment had been ended, the tensile strength was 28.5kgf/$cm^2$ and the elongation was 250% in result. So, this study can propose the spray water-soluble rubber asphalt to satisfy the security and durability of waste filled land.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.498-500
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• 1999

Polyacetals with melamine were investigated in terms of mechanical properties. It was found that tensile strength, impact strength and elongation were decreased with the increase of melamine content up to 30 par, flexural strength had no remarkable changes. For master-batch using polyurethane as carrier resin, in which the ratio of polyurethane to melamine was 2:1, tensile strength and flexural strength were decreased and impact strength remained unchanged with melamine me content.

• Textile Coloration and Finishing
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• v.17 no.1
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• pp.30-37
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• 2005

The tensile properties, acetic acid solubility and degree of swelling in distilled water of cellulose/chitosan and sericin/chitosan film blended by mixing chitosan acetic acid solution with cellulose solution or sericin solution were investigated and the effect of crosslinking agent on solubility and degree of swelling were also considered. From the experimental results, the model of intermolecular bond is proposed. Tensile modulus of 100% cellulose film is high but the tensile strength and elongation are low. The elongation of 100% chitosan film is high but tensile modulus and strength is low. But it is possible to make film having same or higher tensile strength and modulus compared to that of 100% cellulose film by mixing cellulose and chitosan or by mixing sericin and chitosan. Chitosan is solved in 5vol % acetic acid solution but cellulose and sericin are not solved. Degree of swelling of chitosan in distilled water is higher than that of cellulose and sericin. Lower than 40wt% chitosan content, the solubility of cellulose/chitosan film in 5vol % acetic acid solution shows lower expected value but higher in case of sericin/chitosan film.

• Journal of Ocean Engineering and Technology
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• v.23 no.3
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• pp.40-45
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• 2009

With the increase in the annealing temperature, the volume fraction of austenite phase increased and the volume fraction of ferrite phase decreased. In compliance with the addition of N, not only the volume fraction of austenite phase was increased but also the austenite structure was made larger. Volume fraction of ${\sigma}$ phase was increased by decreasing of the volume fraction of ferrite phase, with the increase in the aging time and in compliance with the addition of N. As increasing in volume fraction of ${\sigma}$ phase, tensile strength and hardness increased, while elongation and impact value decreased. Elongation slowly decreased and impact value rapidly decreased at the early stage of aging. By the added N, tensile strength, elongation, hardness and impact value was increased.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.63-70
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• 1991

Aluminium alloy castings, which can be not only manufactured in larger geometrically complex shapes, but also show good mechanical properties in addition to light weight, have kept their potential use as structures in the field of automotives, industrial machines and aircrafts. The variations of eutectic Si size a great effect on the elongation, impact value, fracture toughness and fatigue crack propagation rate without changes in the tensile strength or yield strength. The cooling curves with the solidification rate between $1.4^{\circ}C\;/min$ and $19.1^{\circ}C\;/min$ were obtained. With the increase of solidification rate, DAS, eutectic Si size and grain size were all decreased, which enhanced the mechanical properties. The tensile strength and yield strength were the most greatly influenced by DAS, and the elongation and impact value by eutectic Si size.