• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.46-48
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• 1988

The effect of cold reduction ratio on magnetic properties of 45% Ni-Fe permalloy was studied. To know the relationship between the crystal orientation and the magnetic properties, the pole figure was measured by X-ray diffraction method. In the case of single rolled reduction, the coercive force decreased with cold reduction ratio monotonically, but the maximum permeability, induction and squreness increased drastically. In the case of double rolled reduction (total reduction ratio is 90%), the saturation and residual induction increased slightly with secondary reduction ratio, but the maximum permeability and the coercive force had the maximum and the minimum value at the 50/50% reduction ratio respectively. And strong {100} <100> pole was developed by increasing the cold reduction ratio.

• 한국주조공학회지
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• 제3권1호
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• pp.3-12
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• 1983

The influence of columnar dendirtes on the mechanical properties of Al-1% Cu alloys as unifirectionalloy solidified under the conditions of controlled crystal growth rate (R) and temperature gradient (G) was investigated. And the change of metallography and mechanical properties when unifirectionalloy solidified alloys and cast alloys were cold-rolled from 10% to 90% in reduction ratio was studied. The results are as follows: 1. The elongation and yield strength of unifirectionalloy solidified alloy are higher then those of cast alloy, but there is a little decrease in ultimate tensile strength. 2. The metallography and mechanical properties are changeable with the primary arm spacings when the unidirectionalloy solidified alloys were cold-rolled from 10% to 90% in reduction ratio. An alloy with larger primary arm spacings was easily changeable in metallography and mechanical properties when it was cold-rolled. 3. The tensile strength of transversely cold-rolled to 90% in reduction ratio was higher then that of longitudionalloy cold-rolled to 90% in reduction ratio. In the case, the fractorgraphs of fractured surface showed that the cast alloy and the unifirectionalloy solidified alloy was ductile-fractured, but the surface of transversely cold-rolled to 90% reduction of unidirection alloy solidified was slip plane qracture.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.543-546
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• 2008

In the present study, the effect of cold reduction ratio on the spherodization rate of SK85 high carbon steel sheet was investigated. High carbon steel sheet fabricated by POSCO was soaked at $800^{\circ}C$ for 2 hr in a box furnace and then treated at $570^{\circ}C$ for 5 min in a salt bath furnace followed by water quenching to obtain a fine pearlite structure. Cold rolling was conducted on the sheets of fine pearlite by reduction ratios of 20, 30, and 40 % and heat treatment for spheroidization was carried out at $720^{\circ}C$ for the various time intervals from 0.1 to 32 hrs. Area fraction of spheroidized cementite was measured with an image analyzer as a function of cold reduction ratios and duration times.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.102-105
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• 2008

To investigate the evolution of deformation texture during cold rolling deformation, cold rolling process on a commercial Al-5% Mg sheet was carried out at different rolling reduction ratio. The evolution of annealing texture in cold-rolled Al-5% Mg sheet was also investigated. The evolution of recrystallization texture during annealing process strongly depends on the rolling reduction ratio before heat treatment. Visco-plastic self-consistent (VPSC) polycrystal model was used to predict r-value anisotropy of the cold-rolled and annealed Al-5% Mg sheets. The change of volume fraction for the major texture components was also analyzed.

• Steel and Composite Structures
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• 제21권3호
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• pp.629-659
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• 2016

In cold-formed stainless steel lipped channel-sections, web openings are becoming increasingly popular. Such openings, however, result in the sections becoming more susceptible to web crippling, especially under concentrated loads applied near the web opening. This paper presents the results of a finite element parametric study into the effect of circular web openings on the web crippling strength of cold-formed stainless steel lipped channel-sections for the interior-one-flange (IOF) loading condition. This involves a bearing load applied to the top flange of a length of member, away from the end supports. The cases of web openings located centred beneath the bearing load (i.e. beneath the bearing plate delivering the load) and offset to the bearing plate, are considered. Three grades of stainless steel are considered: duplex EN1.4462, austenitic EN1.4404 and ferretic EN1.4003. In total, 2218 finite element models were analyzed. From the results of the parametric study, strength reduction factors for load bearing capacity are determined, where these reduction factors are applied to the bearing capacity calculated for a web without openings, to take account the influence of the web openings. The strength reduction factors are first compared to equations recently proposed for cold-formed carbon steel lipped channel-sections. It is shown that for the case of the duplex grade, the strength reduction factor equations for cold-formed carbon steel are conservative but only by 2%. However, for the cases of the austentic and ferritic grades, the cold-formed carbon steel equations are around 9% conservative. New strength reduction factor equations are proposed for all three stainless steel grades.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.355-356
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• 2009

The change of thermal expansion and mechanical behaviors by cold working has been investigated in Fe-29%Ni-17%Co low thermal expansion Kovar alloy. Fe-29%Ni-17%Co alloy was cold rolled gradually and prepared to plates having reduction ratio of 0%, 20%, 40%, 60%, and 80%. Annealing effect on the properties was also studied. Thermal expansion was measured from $25^{\circ}C$ to $600^{\circ}C$ with a heating rate of $5^{\circ}C$/min by using vacuum differential dilatometer. It was found that thermal expansion coefficient ($\alpha_{30{\sim}400}$) slightly decreased (reduction ration of 20%) and then remarkably increased (above reduction ration of 40%) with increasing reduction ratio of cold rolling. Thermal expansion coefficient ($\alpha_{30{\sim}400}$) was sharply decreased after annealing heat-treatment. Yield and tensile strengths were continuously increased and elongation was decreased by cold roiling. Microstructural observation and X-ray diffraction analysis results showed that the $\alpha$ phase significantly increased as the reduction ratio increased. The slight decrease of thermal expansion coefficient bellow reduction ration of 20% could be explained by the destroying short-range ordering and the decreasing of grain size. The significant increase of thermal expansion coefficient with cold rolling mainly attributed to the appearance of $\alpha$ phase. The correlation between the microstructural cause and invar phenomena for the low thermal expansion behavior was also discussed.

• 열처리공학회지
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• 제30권6호
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• pp.251-257
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• 2017

The effect of annealing temperature on the martensitic transformation behavior, tensile deformation chracteristics and shape recovery etc., has been studied in TiNi based shape memory ribbon fabricated by coldrolling of wire. TiNi based shape memory wire (${\phi}=500{\mu}m$) of which structure is intermetallic compound could be cold-rolled without process annealing up to the reduction rate in thickness of 50%, but a few cracks appear in cold-rolled ribbon in the reduction rate in thickness of 65%. The $B2{\rightarrow}R{\rightarrow}B19^{\prime}$ martensitic transformation or $B2{\rightarrow}B19^{\prime}$ martensitic transformation occurs in annealing conditions dissipating lattice defects introduced by coldrolling. However, in case of higher reduction rate or lower annealing temperature, martensitic transformation in cold-rolled and then annealed ribbons does not occur. The maximum shape recovery rate of cold-rolled ribbons with the reduction rate of 35 and 65% could be achieved at annealing temperatures of 250 and $350^{\circ}C$, respectively. The shape recovery rate seems to be related to the stress level of plateau region on stress-strain curve.

• 한국작물학회지
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• 제50권3호
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• pp.205-211
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• 2005

본 연구는 저온에 민감한 밀양 23호를 모본으로 내냉성이 강한 Stejaree45호를 부본으로 교잡하여 육성한 175 RILs를 이용하여 내냉성 관련 형질들의 변이분포, 유전 통계량 및 상관 관계를 분석하였다. 조사된 형질 중 수당영화수, 적고, 출수지연일수, 간장단축율 및 영화수감소율은 정규분포에 가까운 연속변이 분포곡선을 보였으며, 모든 형질에서 양친의 범위를 벗어나는 초월분리현상을 보였다. 임실감소율과 수량감소율은 모본인 밀양 23호 쪽으로 일정하게 치우친 경향으로 저온에 민감한 쪽으로, 출수지연일수와 간장단축율은 부본인 Stejaree45 쪽으로 치우친 경향으로 내냉성이 증가되는 쪽으로 작용가가 큰 유전자가 관여하는 것으로 추정되었다. 내냉성 관련 형질들의 상관관계 중 수량감소율과 상관이 인정되었던 형질은 출수지연일수, 간장단축율, 이삭추출도 및 임실감소율이었고, 조사된 형질중 유전력이 $60\%$이상으로 나타난 형질은 분얼기 적고, 임실감소율, 이삭추출도 였으며, 유전력이 $40\%$ 이하로 낮았던 형질은 간장단축율, 영화수감소율 및 수량감소율이었다. 175 RILs 중에서 내냉성 관련 형질의 내냉성 정도가 부본인 Stejaree45수준이거나 그 이상의 내냉성 형질을 가진 것은 86계통으로, 1개의 내냉성 형질은 56계통 $32.0\%$였고, 2개의 내냉성 형질은 25계통 $14.3\%$, 3개의 내냉성 형질은 4계통 $2.3\%$, 4개의 내냉성 형질은 1계통 밖에 없었으며, 그 이상의 내냉성 관련 형질을 가진 계통은 없었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
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• pp.85-90
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• 2001

The microstructure and mechanical property of 0.19C-1.17Cr steel were investigated with cold drawing. This commercial steel has the microstructure that is consist of ferrite and pearlite. The tensile and yield strength are increased as the reduction ratio of cold drawing is increased. It was clear that mechanical properties could be improved by combination of the heat treatments and reduction ratio. Yield strength. tensile strength, and impact value were formulated as a constitutive function of cold drawing ratio, respectively.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.382-385
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• 2008

In the present study, the effect of cold reduction ratio on the spheroidization rate of SK85 high carbon steel sheet was investigated. High carbon steel sheet fabricated by POSCO was soaked at $850^{\circ}C$ for 2 hr in a box furnace and then treated at $570^{\circ}C$ and $670^{\circ}C$ for 10 min in a salt bath furnace followed by water quenching to obtain a fine pearlite structure and coarse pearlite structure. Cold rolling was conducted on the sheets by reduction ratios of 20, 30, and 40 % and heat treatment for spheroidization was carried out at $720^{\circ}C$ for the various time intervals from 1 to 32 hrs. Area fraction of spheroidized cementite was measured with an image analyzer as a function of cold reduction ratios and duration times.