Advanced Materials Research Vols. 535-537

Abstract: Abstract: Spray forming UHCS-1.6Al material has a refined equiaxed pearlitic structure, which was necessary for high-train-rate superplasticity. During deformation, the cementite particles pin the grain boundaries and prevent the grains growing up. As a result it exhibited excellent high-strain-rate superplasticity, with a peak ductility of 187% occurring at a strain rate of 5*10-3s-1.

Abstract: The DWTT fracture toughness of X70 pipeline steel with different content and grain size of polygonal ferrite was investigated. The results show that when the content of polygon ferrite is above 28%, the shear-area percentage of DWTT fracture begins to decrease instead of increase, while polygonal ferrite toughening effect weakens. It is the difference of the polygonal ferrite content that results in the difference of shear-area percentage of DWTT fracture.

Abstract: For the elimination of the fluorine pollution of steelmaking slag, boron mud is employed as fluxing agent for CaO-based fluorine-free slag. The effect of boron mud on the melting properties of slag is investigated. Hemisphere method is used to determine the melting temperature of samples. The results indicate that when the content of boron mud is lower than 7%, the melting temperature can be decreased by boron mud. With the content of boron mud increasing higher than 7%, the melting temperature is increased with increase of boron mud content. The basicity and the content of F2O3 have remarkable effect on the melting temperature of boron mud containing slag. When the basicity is in scope of 2.0-5.0, the melting temperature is in the range of 1350-1450°C correspondingly. The melting temperature of boron mud containing slag can be decreased significantly with increase of F2O3 content.

Abstract: The shield thermal neutron performance of two high boron alloyed stainless steel composite plates(HBASSCP) was studied by the method of neutron beam transmission of neutron source reactor. The testing results indicate that the shield performance of the composite material is heavily affected by the size and distribution of the boride. Although the radiationresistance of high boron alloyed stainless steel increases with boron content, but blocky and sparse hypereutectic boride will appear in matrix when boron content is high (more than 3%), and these borides are difficult to be broken during hot deformation, so the thermal neutron is easy to penetrate directly through the space and can not be absorbed effectively. The difference between the shield performance obtained from experiments and the theoretical calculation is small for HBASSCP containing hypoeutectic boride in core material, but it is great for HBASSCP containing hypereutectic boride in core material.

Abstract: The effects of tempering temperature on the microstructure and mechanical properties of 600MPa grade low carbon bainitic steel were investigated. The cause for the microstructure evolution has been investigated and the best tempering process was chosen to decrease the yield ratio of the steel. The influence of tempering process on the yield-to-tensile ratio of steels has been investigated by the aid of optical microscopy, SEM and XRD. The results show that after the TMCP processing the microstructure of steels mainly consist of lath martensite and bainite. The bainite and martensite have been refined markedly after the relaxation processing, therefore the properties of steels has been improved evidently. In order to decrease the yield-to-tensile ratio the steels underwent high temperature tempering. It has been found that during the tempering with the tempering temperature increased the yield-to-tensile ratio of steels decreased. The XRD and EBSD results show tempering temperature has considerable influence on the yield strength, but the influence on the tensile strength is not considerable. With the increase in tempering temperature, the low temperature toughness of steel can be improved considerably. The yield ratio of the steel was reduced after tempering at 650 °C and higher temperatures due to reversed austenitic phase transformation.

Abstract: Silicon steel plate is main material of motor and transformer , and can be produced by Laser cut or water cut . The advantage and disadvantage of laser cut and water cut was analyzed from the economy and technology point of view . It will provide one way of economy and technology analysis for enterpriser and one way of production for new motor and transformer trial-produce .

Abstract: The effects of RE metals on the inclusions and the impact property of 430 ferrite stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of inclusions in 430 ferrite stainless steel are changed, and RE played a very good role of modifying inclusions. The fracture mode of 430 ferrite stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel. The transverse impact property of 430 ferrite stainless steel is improved obviously by RE. In comparison with 430 ferrite stainless steel without RE, the transverse impact property of 430 ferrite stainless steel with RE is increased 38.53% at -20°C, respectively.

Abstract: The microsructural and content of δ ferrite in non-equilibrium solidified 0Cr18Ni9 austenitic stainless steel is studied by the coin with the circulating water. The solidified microstructure of the residual δ ferrite in different cooling rate is that during the course of solid-state transformation, austenite grows into ferrite gradually; corresponding to the increase of cooling rate, the microsructural of ferrite is skeletal, network, strip and block. The experiment demonstrates that the content of the residual δ ferrite is increase under the increase of the cooling rate.

Abstract: C-Mn-Cr-Mo dual phase steel was piloted in laboratory. OM, SEM, tensile tests and XRD were used to characterize the microstructures, mechanical properties and to determine the texture. The results indicate that when annealed at 860 °C, the tensile strength of the tested steel is 440 MPa, elongation and r value exceed 35% and 1.4, respectively. With the temperature increases from 820°C to 860°C, the average grain size of ferrite increases and ferrite trends to be uniform gradually, therefore, the r value increase gradually. When the temperature is higher than 860°C, bainite forming results in reducing of r value. Al could weaken the tendency of heterogeneous deformation and modified the annealing texture by refining hot-rolling grain size. Mo-based carbides existed in hot-rolled sheet developed {111} texture in the stage of ferrite recrystallization, then re-dissolved in intercritial annealing stage so as to improve hardenability.

Abstract: A creep-fatigue life prediction model for P91 steel using Improved Elman Neural Network is founded based on the creep-fatigue experiment datas in this paper. The load keeping time is selected as the model input and the creep life or fatigue life as the output in the model. The prediction ability is validated from training the sample data. The results show the model has a very high prediction accuracy for training samples. But the model generalization ability is relatively weak, so the forecasting accuracy for test sample is lower than the training samples. Through increasing test sample number and decreasing the uncertain factors during the experiment in the follow-on working, the prediction accuracy and the model generalization ability will be increased.