• 한국주조공학회지
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• 제30권2호
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• pp.66-75
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• 2010

The effects of alloying elements on the mechanical properties of normalized and quenched 3.60wt%C-2.60wt%C ductile cast iron poured into shell stack mold were investigated. The strength and hardness of as-cast specimen were increased and the elongation of it was decreased with the additions of Mn, Cu and Sn. The strength and hardness were increased with the addition of 0.40wt%Mo and then rather decreased with the increased addition of 0.80wt%. The strength and hardness were increased with normalizing treatment and the strengths of normalized specimens were increased slightly with the addition of alloying elements except Mo. Meanwhile the yield strength of the normalized specimen was increased slightly with the addition of Mo, the tensile strength was not changed much. Meanwhile the hardness and strength of the quenched specimen were slightly increased with the addition of Mn, those were almost not changed with the amount added. The tensile strength of the quenched specimen with larger diameter, when the Cu had been added, and the tensile and yield strengths of them, when Mo had been added, were increased with the addition of alloying element. On the other hand, those were not changed with the amount added. For the case of specimen with smaller diameter, there were no effects of these two elements. When Sn had been added, the strength of hardened specimen with larger diameter was slightly increased with the amount added. However, that with smaller diameter was rather decreased with it. The effect of specimen diameter on the strength of quenched specimen with the addition of Cu, Mo and Sn was reduced.

• 열처리공학회지
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• 제27권3호
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• pp.121-126
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• 2014

High-nitrogen Fe-18Mn-18Cr-N austenitic steels with higher yield strength have been recently developed and used for generator retaining rings because they have non-magnetic, high strength, high ductility, and good corrosion resistance. In the present study, a high-nitrogen Fe-18Mn-18Cr-0.61N austenitic steel was fabricated and then tensile and Charpy impact tests were conducted on them in order to investigate the effect of cold working on the mechanical properties. Although the yield and tensile strengths usually increased with cold working, the ductility and impact toughness significantly decreased after cold working. On the other hand, the high-nitrogen austenitic steel exhibited a ductile-brittle transition due to unusual brittle fracture at low temperatures despite having a face-centered cubic structure. The ductile-brittle transition temperature obtained from Charpy impact tests could be remarkably increased by $60^{\circ}C$ after 20% cold working because of the enhanced cleavage-like brittle fracture.

• 반도체디스플레이기술학회지
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• 제3권2호
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• pp.23-26
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• 2004

Thin film is one of the most general structures used in micro-electro-mechanical systems (MEMS). To measure the mechanical properties of SU-8 film, tensile testing was adopted which offers not only elastic modulus but also yield strength and plastic deformation by load-displacement curve. Tensile testing system was constructed with linear guided servo motor for actuation, load cell for force measurement and dual microscope for strain measurement.

• 한국정밀공학회지
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• 제18권1호
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• pp.129-138
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• 2001

This study examined the effects of the annealing heat treatments on the mechanical properties of the Invar(Fe-36%Ni Alloy) materials. Invar materials were annealed at various temperatures range 900~120$0^{\circ}C$ in vacuum(10-4Torr) and hydrogen atmospheres. And annealing conditions were changed by cooling rate and holding time at 110$0^{\circ}C$. The grain size of rolled Invar materials was very fine but those of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere increased with increasing annealing temperature. The micro-vickers hardness values of annealed Invar materials were decreased about 15% that of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions. The tensile strength and yield strength of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere were decreased 10.0~14.4% and 34.6~39.1% those of the rolled Invar materials, respectively. The strength ratio(tensile strength/ yield strength) of annealed Invar materials was improved to 1.7~1.8 from the value of 1.2~1.3 of rolled Invar materials. The degree of spring back of annealed Invar materials was about 50% of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions.

• Steel and Composite Structures
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• 제30권2호
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• pp.171-183
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• 2019

As China's infrastructure continues to grow, concrete filled steel tubular (CFST) structures are attracting increasing interest for use in engineering applications in earthquake prone regions owing to their high section modulus, high strength, and good seismic performance. However, in a corrosive environment, the seismic resistance of the CFST columns may be affected to a certain extent. This study attempts to investigate the mechanical behaviours of square CFST members under both a cyclic load and an acid rain attack. First, the tensile mechanical properties of steel plates with various corrosion rates were tested. Second, a total of 12 columns with different corrosion rates were subjected to a reversed cyclic load and tested. Third, comparisons between the test results and the predicted ultimate strength by using four existing codes were carried out. It was found that the corrosion leads to an evident decrease in yield strength, elastic modulus, and tensile strain capacity of steel plates, and also to a noticeable deterioration in the ultimate strength, ductility, and energy dissipation of the CFST members. A larger axial force ratio leads to a more significant resulting deterioration of the seismic behaviour of the columns. In addition, the losses of both thickness and yield strength of an outer steel tube caused by corrosion should be taken into account when predicting the ultimate strength of corroded CFST columns.

• 소성∙가공
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• 제32권2호
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• pp.53-60
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• 2023

A wide range of grain size was achieved in a Fe-Cr-Mn austenitic stainless steel (STS) by cold rolling and reversion annealing. The tensile characteristics of the STS were analyzed in terms of the dependence of strain induced martensitic (SIM) transformation on the grain size. In the ultrafine grain regime, the steel showed a high yield strength over 1 GPa, a discontinuous yielding, and a prolonged yield point elongation followed by considerable strain hardening. By increasing the grain size, the discontinuous yielding diminished and the yield point elongation decreased. The microstructural examination revealed that these tensile characteristics are closely related to the suppression of SIM transformation with decreasing the grain size. Especially, the prolonged yield point elongation of the ultrafine grained STS was found to be associated with development of unidirectional ε martensite bands. Based on the microstructural examination of the deformed microstructures, the rationalization of the grain size dependence of SIM transformation was suggested.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.307-310
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• 1999

In this panel test, the toughness and post-cracking tensile strength of SFRC(Steel Fiber Reinforced Concrete) measured on 24 panels(size; 60cm $\times$ 60cm $\times$ 10cm) which are the basic characteristics than can determine the load bearing capacity of SFRC are investigated. Those values are calculated using load-deflection curves and load-absorbed energy curves. Post-cracking tensile strength of SFRC in this study are determined by yield line theory. From the test results, it is seen that the higher the volume of steel fiber is, the higher the absorbed energy is.

• 한국정밀공학회지
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• 제22권12호
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• pp.28-33
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• 2005

• 오토저널
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• 제9권3호
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• pp.76-84
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• 1987

A study has been made to clarify the microstructural effect on static tensile properties of the dual phase steel, in which the martensitic phase encapsulated islands of ferritic phase. The main results are as follows: Yield strength is associated with the degree of plastic constraint factor and tensile strength increases with increasing of strain hardening exponent. Also, the variation of ductility is dependent upon the amount of micro-brittle facets.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1365-1372
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• 2019

The effects of Y and Ti on the microstructure stability and tensile properties of the reduced activation ferritic/martensitic steel have been investigated. The addition of Y and Ti affected the prior austenite grain size due to the pinning of the inclusions. Ti addition of 0.008 wt% to the steel was intended to promote the precipitation of nano-sized carbides with a high resistance to coarsening. 8Ti14Y exhibited a higher yield strength and a lower DBTT than the other alloys due to the fine grain size and additional precipitation hardening by (Ti, Ta)-rich MX. After thermal exposure at $550^{\circ}C$ for 1500 h, yield strength was dropped significantly in exposed 0Ti13Y. On the contrary, a lower reduction of YS was observed in 8Ti14Y. The $M_{23}C_6$ in 0Ti13Y and 8Ti14Y and MX in 25Ti14Y and 39Ti15Y coarsened seriously during ageing, which could be responsible for the reduction of the tensile properties of alloys.