In order to understand the effects of soaking time and confined water pressure on the strength of rock due to dissolution of gypsum,rock samples with 96% of gypsum content collected from Kurdistan Region in northern I...In order to understand the effects of soaking time and confined water pressure on the strength of rock due to dissolution of gypsum,rock samples with 96% of gypsum content collected from Kurdistan Region in northern Iraq were investigated.Laboratory tests were then performed on the normal gypsum rock samples under pre-saturated condition to obtain their uniaxial compressive strength(UCS) values.The pre-saturated samples were submerged in distilled water for 35 d,70 d and 105 d,respectively,under confined water pressures of 0-0.5 MPa.The gypsum content decreased by 11% after 105 d of soaking under confined water pressure of 0.5 MPa.The UCS of the normal gypsum rock was 19.6 MPa and it decreased to 6.3 MPa and 2 MPa after 105 d of soaking under confined water pressures of 0 and 0.5 MPa,respectively.A nonlinear constitutive model was used to simulate the experimental stress-strain relationships of rock samples under various conditions.The constitutive model parameters were sensitive to the gypsum content.展开更多
The recrystallization behavior of cold-drawn 0.12 wt% C steel during annealing at temperatures 600°C and 650°C was investigated. Hardness tests were used to characterize the recrystallization kinetics. The m...The recrystallization behavior of cold-drawn 0.12 wt% C steel during annealing at temperatures 600°C and 650°C was investigated. Hardness tests were used to characterize the recrystallization kinetics. The micrographs of the steel were obtained using optical microscopy (OM) to characterize the grain microstructure of the non-treated and the annealed steel samples. Annihilation of dislocation defects occur within the soaking time of 5 - 10 minutes for all the deformed steel after annealing at 650°C. Specifically at 5 minutes soaking time the grains elongation is still observed indicating that reformation of grains is not taking place but recovery of the deformed grains. At the 10 minutes annealing time, new grains are observed to begin and full recrystallization is achieved at 15 minutes annealing time. At annealing time between 20 - 25 minutes, grains coarsening are observed indicating the onset of grain growth. The hardness of the material reduces with increasing annealing temperature for all the degree of cold drawn deformation. On the basis of the experimentally obtained hardness values, recrystallization increases with increasing degree of cold drawn deformation for the annealed steel. Recovery process was found to prolong in the 20% cold drawn steel as compared to the 55% cold drawn steel. The prolong recovery process is due to reduction in the driving force. Full recrystallization of the annealed steel is achieved at different soaking time depending on the degree of the cold drawn steel.展开更多
[Objectives] To optimize volatile oil extraction from Ocimum basilicum with the water vapor distillation. [Methods] An orthogonal design was carried out to determine the volume of volatile oil by 3 factors: the immers...[Objectives] To optimize volatile oil extraction from Ocimum basilicum with the water vapor distillation. [Methods] An orthogonal design was carried out to determine the volume of volatile oil by 3 factors: the immersion time, distillation time, amount of water. The ratio of the oil in inclusion complex was used to evaluate the technology based on the orthogonal design. [Results] The best volatile oil extraction condition was to add 400 mL of water into the mixture of crude drugs, and to extract the herbal medicine for 2 h with advanced soaking for 6 h with water. [Conclusions] The process is stable, reasonable, and feasible.展开更多
Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat tre...Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat treatment parameters that could ensure improved toughness and ductility. Determining the optimum annealing parameters ensures valued recrystallization and also minimizes grain growth that could be detrimental to the resulting product. 40% and 55% cold drawn steels were annealed at temperatures 500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval of 10 minutes to identify the temperature range and soaking time where optimum combination of properties could be obtained. Tensile test and impact toughness experiments were done to determine the required properties of the steel. Polynomial regression analysis was used to fit the properties relationship with soaking time and temperatures and the classical optimization technique was used to determine the minimum soaking time and temperature required for improved properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain size of 44.7 mm can be considered to be the optimum annealing treatment for the 40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.展开更多
The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% de...The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.展开更多
基金the lraqi Government (Cultural Attaché,UK) for the financial supporting of the first author's PhD studythe University of Sulaimani,Kurdistan Region of Iraq for their support during this study
文摘In order to understand the effects of soaking time and confined water pressure on the strength of rock due to dissolution of gypsum,rock samples with 96% of gypsum content collected from Kurdistan Region in northern Iraq were investigated.Laboratory tests were then performed on the normal gypsum rock samples under pre-saturated condition to obtain their uniaxial compressive strength(UCS) values.The pre-saturated samples were submerged in distilled water for 35 d,70 d and 105 d,respectively,under confined water pressures of 0-0.5 MPa.The gypsum content decreased by 11% after 105 d of soaking under confined water pressure of 0.5 MPa.The UCS of the normal gypsum rock was 19.6 MPa and it decreased to 6.3 MPa and 2 MPa after 105 d of soaking under confined water pressures of 0 and 0.5 MPa,respectively.A nonlinear constitutive model was used to simulate the experimental stress-strain relationships of rock samples under various conditions.The constitutive model parameters were sensitive to the gypsum content.
文摘The recrystallization behavior of cold-drawn 0.12 wt% C steel during annealing at temperatures 600°C and 650°C was investigated. Hardness tests were used to characterize the recrystallization kinetics. The micrographs of the steel were obtained using optical microscopy (OM) to characterize the grain microstructure of the non-treated and the annealed steel samples. Annihilation of dislocation defects occur within the soaking time of 5 - 10 minutes for all the deformed steel after annealing at 650°C. Specifically at 5 minutes soaking time the grains elongation is still observed indicating that reformation of grains is not taking place but recovery of the deformed grains. At the 10 minutes annealing time, new grains are observed to begin and full recrystallization is achieved at 15 minutes annealing time. At annealing time between 20 - 25 minutes, grains coarsening are observed indicating the onset of grain growth. The hardness of the material reduces with increasing annealing temperature for all the degree of cold drawn deformation. On the basis of the experimentally obtained hardness values, recrystallization increases with increasing degree of cold drawn deformation for the annealed steel. Recovery process was found to prolong in the 20% cold drawn steel as compared to the 55% cold drawn steel. The prolong recovery process is due to reduction in the driving force. Full recrystallization of the annealed steel is achieved at different soaking time depending on the degree of the cold drawn steel.
基金Supported by Key Natural Science Research Project of Higher Learning Institutions in Anhui Province in 2018(KJ2018A0884)the Natural Science Research Program of Anhui Colleges and Universities in 2017(KJ2017A772)
文摘[Objectives] To optimize volatile oil extraction from Ocimum basilicum with the water vapor distillation. [Methods] An orthogonal design was carried out to determine the volume of volatile oil by 3 factors: the immersion time, distillation time, amount of water. The ratio of the oil in inclusion complex was used to evaluate the technology based on the orthogonal design. [Results] The best volatile oil extraction condition was to add 400 mL of water into the mixture of crude drugs, and to extract the herbal medicine for 2 h with advanced soaking for 6 h with water. [Conclusions] The process is stable, reasonable, and feasible.
文摘Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat treatment parameters that could ensure improved toughness and ductility. Determining the optimum annealing parameters ensures valued recrystallization and also minimizes grain growth that could be detrimental to the resulting product. 40% and 55% cold drawn steels were annealed at temperatures 500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval of 10 minutes to identify the temperature range and soaking time where optimum combination of properties could be obtained. Tensile test and impact toughness experiments were done to determine the required properties of the steel. Polynomial regression analysis was used to fit the properties relationship with soaking time and temperatures and the classical optimization technique was used to determine the minimum soaking time and temperature required for improved properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain size of 44.7 mm can be considered to be the optimum annealing treatment for the 40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.
文摘The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.
