• 열처리공학회지
• /
• 제30권2호
• /
• pp.43-52
• /
• 2017

Heat treatment condition for dissolution of the M23C6 carbides in 2.25Cr-1Mo-V-Ti material for thermal power plant tube was investigated using a dilatometer method. 2.25Cr-1Mo-V-Ti material was heat-treated at $900{\sim}1,100^{\circ}C$ for 0, 10, 30 min to find the proper dissolution condition of M23C6 carbides. The phase identification and volume fraction of the carbide were measured by using OM, SEM, EBSD and TEM analysis. Optimal heat treatment condition of M23C6 carbide dissolution was selected by predicting dissolution temperature of carbide using Bs points appeared at dilatometer curve. Experimental results showed that the conditions of carbide dissolution was 900, 1,000, $1,100^{\circ}C$ for 30 min. Eventually, the optimal heat treatment condition for dissolution was 30 min at $1,000^{\circ}C$ considering the minimum coarsening of Austenite grain size.

• 열처리공학회지
• /
• 제7권3호
• /
• pp.184-189
• /
• 1994

The heat treatment charaterristic of SCM 440 and B 16 steels has been investigated in various condition(A, B and C) to the effect of heat treatment on mechanical properties, and the following results were obtained. 1. We are obtained a good nitriding characteristic in bainitic structure than other heat treatment cycle in our experiment. 2. Fatigue characteristic has shown in order of B)C)A condition as heat treatment cycle. 3. The effective hardening depth and fatigue characteristic has been excellented in B 16 than SCM 440 after the nitriding and Q. T for Band C condition. 4. Nitriding depth has been increased in addition of Cr, V and the nitriding efficiency is increased as easiness of banite formation to wide range of cooling rate by addition of Mo. 5. The depth of compound layer in parallel surface, notched slop plane and notched bottom has been varied to the nitriding depth of 5, 4 and 3 ${\mu}$ in relatively uniform pattern after 10h nitriding treatment for SCM 440 into A condition.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 춘계학술대회 논문집
• /
• pp.238-243
• /
• 2011

This study compared Kd, loss factor and thickness of floor impact isolator by loading/unloading heat treatment with results by continuous loading treatment and checked problem and improvement method of heat treatment condition for the long-term stability evaluation of the floor impact isolation. As the results, it is required the change of heat treatment condition unloading now to loading as actual weigh on the floor impact isolator.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.194-204
• /
• 1994

The purpose of this study was to evaluate the surface hardness of composite resins according to heat treatment. storage condition and storage time. In this study. two kinds of composite resin inlays and one kind of conventional posterior composite resin were used as experimental materials. One hundred eighty composite resin specimens were constructed from composite resin inlays and conventional posterior composite resin. The conditions of this study were heat treatment. storage condition and storage time. Hardness readings were taken from the top surface of each samples using the Vickers microhardness tester(MHT-l. Matsuzawa. Japan}. The following results from this study were obtained: 1. Regardless of storage condition. both composite resin inlay and conventional posterior composite resin have a higher surface hardness under heat treatment than not. 2. Composite resins with heat treatment have a higher surface hardness under dry storage than under water immersion. 3. In case of Clearfil Photo Posterior and Brilliant Enamel with heat treatment. there was no significant difference with time. but Clearfil CR Inlay with heat treatment. there was statistical difference after 24 hours. 4. Surface hardness of composite resins with coarse hybrid type was higher than that of composite resin with fine hybrid type.

• 한국정밀공학회지
• /
• 제17권2호
• /
• pp.137-143
• /
• 2000

An automobile clutch diaphragm spring is operating in a closed clutch housing under high temperature and subject to high stress concentration in driving condition, which frequently causes cracks and fracture. The material of spring is required to possess sufficient fatigue strength and tenacity, which depend largely on the condition of tempering heat treatment. In this paper, specimens are made under a number of different tempering temperatures md tested to find the optimal tempering heat treatment condition. The experiments include the verification of microscopic structure, hardness, tensile strength, fatigue crack growth rate, stress intensity factor range and residual stress. Also, decarbonization, which occurs in actual heat treatment process, is measured and allowable decarbonization depth is studied by durability test.

• 열처리공학회지
• /
• 제12권4호
• /
• pp.303-312
• /
• 1999

An investigation of the CrMoV rotor steel weldment which experienced by cyclic thermal aging heat treatment and as-received condition was performed. This evaluation was carried out to confirm whether this type of weldment is appropriate for the service environment in terms of microstructural examinations, microhardness measurements and tensile tests. The cyclic thermal aging heat treatment, containing continuous heating and cooling thermal cycle was programmed to simulate the real rotor service condition. The heat treatment was performed for 40 cycles(5920hrs). The results indicated that the weldment was composed of 4 different regions such as heat affected zone of the base metal, butter weld(initial weld), full thickness weld(final weld) and the base metal. The double welding process was applied to eliminate the susceptibility of reheat cracking at heat affected zone of base metal. The grain refinement at the HAZ due to the welding process could reduce the possibility of cracking susceptibility, but its tensile properties was appeared to be low due to the weld metal in as-received condition. The benefit effect, grain refinement was extended with carbides coarsening during the cyclic thermal aging heat treatment. However the poor mechanical properties of the weldment was more degraded as undergoing the heat treatment.

• 임산에너지
• /
• 제21권3호
• /
• pp.10-17
• /
• 2002

본 연구는 단소용 대나무 악기재를 효과적으로 건조하기 위하여 열처리 및 몇 가지 스케줄에 의한 건조를 실시하였다. 평균 직경 2.2cm, 길이 60cm정도의 솜대를 이용하였다. 열처리 효과를 평가하기 위하여 무처리 및 열처리재로 구분하였으며 적당한 건조 조건 조사를 위해서 20℃, 65%와 40℃, 40% 그리고 대기상태의 3가지 조건으로 실시하였다. 탄화와 재색의 결함이 발생하지 않는 열처리의 최적 온도 조건은 180℃정도가 적당하였으며 열처리가 할렬의 수와 할렬 크기의 발생을 줄였으며 건조결함을 발생하지 않는 최적의 조건은 온도 20℃, 관계습도 65%이지만 건조를 할 때 기간이 너무 많이 소요되는 단점이 있기 때문에 40℃, 40%에서 건조시키는 것이 더욱 효율적이었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.293-295
• /
• 1987

This paper deals with the dielectric properties dielectric breakdown strength and mechanical tensile properties according to heat - treatment condition of polyurethane resin. This resin is heat - treated over a range of temperature from $50^{\circ}C$ to $150^{\circ}C$. It is shown that the dielectric dissipation factor decreases with increase of heat - treatment temperature of the sample exept for the sample heat - treated at $150^{\circ}C$. The maximum dielectric breakdown strength is appeared for the sample heat - treated for 10 hours at $100^{\circ}C$, after curing for 24 hours at room temperature. The optimal heat - treatment condition in the view point of the electrical and mechanical properties is appeared for the sample heat - treated for 10 hours at $100^{\circ}C$, after curing for 24 hours at room temperature.

• 한국주조공학회지
• /
• 제25권6호
• /
• pp.226-232
• /
• 2005

Contact material is widely used in the field of electrical parts. Ag-CdO material has a good wear resistance and stable contact resistance. In order to establish optimizing heat treatment condition, rolling temperature and oxidation process, we studied the microstructure of Ag-CdO material with various conditions. The experimental procedure were melting using high frequency induction, heat treatment, rolling and internal oxidation. And we experimented on difference process, Post-oxidaion. In this study, we obtained the optimizing heat treatment condition was $700^{\circ}C$ for 15 min. and the optimizing rolling temperature was $730^{\circ}C$. In investigation of the microstructure of oxidized material, coarse oxide and depleted oxidation layer existed. The hardness was average Hv 70. When we used Post-oxidation, oxides were finer than prior process and depleted oxidation layer did not exist. The hardness of Post-oxidation material was average Hv 80. And the optimizing rolling temperature was $800^{\circ}C$.

• 대한치과기공학회지
• /
• 제17권1호
• /
• pp.5-9
• /
• 1995

This study was carried out by obsorving to the conditions of an oxide on the surface of alloy according to the conditions of its heat treatment and analysing the change in composition on its surface. The result of this study is summarized as fellows. 1. It was shown that the higher the more the generated metal oxide while the higher the temperature of heat treatment. 2. The metal oxide was manily composed of Ni and Cr oxides. 3. The Ni composition indicated reduction while the higher the heat treatment in vaccum condition. 4. The Cr composition indicated increase while the higher the heat treatment in vaccum condition.