Grain refinement and formation of ultrafine-grained microstructure in a low-carbon steel under electropulsing

2002 ◽  
Vol 17 (8) ◽  
pp. 2105-2111 ◽  
Author(s):  
Yizhou Zhou ◽  
Wei Zhang ◽  
Baoquan Wang ◽  
Guanhu He ◽  
Jingdong Guo

High current electropulsing was applied to a low-carbon steel in the solid state. The relationship between grain size and experimental conditions was revealed. It was found that the ultrafine-grained (UFG) microstructure could be formed when electric current density, heating rate, and cooling rate all were high. The UFG samples prepared by applying electropulsing were free of porosity and contamination, and had no large microstrain. Also, their tensile strength was dramatically enhanced over that of their coarse-grained counterparts, without a decrease in ductility. The mechanism for grain refinement and formation of the UFG microstructure was discussed. It is proposed that the effect of a decrease in thermodynamic barrier and enhancement of nucleation rate in a current-carrying system cannot be neglected.

2010 ◽  
Vol 654-656 ◽  
pp. 1223-1226 ◽  
Author(s):  
Jozef Zrník ◽  
Sergey V. Dobatkin ◽  
George Raab ◽  
Libor Kraus

The present work deals with grain refinement in low carbon steel (AISI 1010) by severe plastic deformation (SPD). The effect of structure modification was evaluated with respect to thermomechanical (TM) treatment of steel prior to SPD. The grain refinement was accomplished during warm angular channel pressing (ECAP) at 300°C. The evolution of microstructure during equal channel angular pressing (ECAP) was studied using SEM and TEM of thin foils. Ultrafine-grained structure development is described in relation to strainintroduced. At lower strain applied, the subgrain and/or polygonized structure was frequently found. Due to increased deformation temperature, the dynamic recovery contributed to structure refinement in both structural states. The amount of high angle boundaries increased with higher ECAP strain and was higher in TM-processed steel. There was only an indistinctive difference in structure refinement, considering different initial structures of the steel.The deformation behaviour of UFG steel in dependence on processing conditions was evaluated by a tensile test and correlated with structural characteristics.


2018 ◽  
Vol 1145 ◽  
pp. 1-7
Author(s):  
Yuan Long Yang ◽  
Qing Chun Meng ◽  
Wei Ping Hu

In the paper, the relationship between the grain size and fatigue life are studied. To specify the initial and short crack propagation life of low carbon steel material, three methods are used in the simulation. At first, the K. Tanaka’s model is introduced to calculate the fatigue life of a grain. Then, the Voronoi Diagram is used to generate the microstructure of grains. At last, a criteria to specify the short crack is proposed. Based on these methods, the numerical simulation is conducted. With the help of the process, the grain sizes are generated randomly in order to specify how grain sizes effect fatigue life. The computational results are in good agreement with the experimental data. The results show that the randomness of fatigue life is closely related to the randomness of grain sizes.


Author(s):  
Ya.G. Avdeev ◽  
◽  
A.V. Panova ◽  
T.E. Andreeva ◽  
Yu.I. Kuznetsov ◽  
...  

Corrosion of 08PS low-carbon steel was studied in a wide temperature range t = 25—100 °C in 1 M H2SO4 + 1 M H3PO4, 2 M H2SO4 и 2 M H3PO4, inhibited by the binary mixture IFKhAN-92 + KNCS (a molar ratio of components 9:1) and a three-component mixture IFKhAN-92 + KNCS + urotropine (9:1:400), in the presence of high concentrations of Fe(III) and Fe(II) salts, as well as in their joint presence. It is shown that under experimental conditions the corrosion inhibitors under study provide effective protection of steel in 1 M H2SO4 + 1 M H3PO4 even in the presence of Fe(III), Fe(II) salts or their mixtures. The highest protective effects are provided by a three-component inhibitor mixture. Under similar conditions in individual 2 M H3PO4 and, especially, 2 M H2SO4, the protective effects of inhibitors are lower. A stronger deceleration of steel corrosion by composite inhibitors based on IFKhAN-92 in H2SO4 + H3PO4 solutions containing Fe(III) salts in comparison with similar solutions of individual H2SO4, is largely due to the binding of Fe(III) cations by phosphate anions into complexes, that significantly reduces their chemical activity and, as a result the corrosion rate of steel.


2021 ◽  
Vol 1016 ◽  
pp. 42-49
Author(s):  
Kook Soo Bang ◽  
Joo Hyeon Cha ◽  
Kyu Tae Han ◽  
Hong Chul Jeong

The present work investigated the effects of Al, Si, and N content on the impact toughness of the coarse-grained heat-affected zone (CGHAZ) of Ti-containing low-carbon steel. Simulated CGHAZ of differing Al, Si, and N contents were prepared, and Charpy impact toughness was determined. The results were interpreted in terms of microstructure, especially martensite-austenite (M-A) constituent. All elements accelerated ferrite transformation in CGHAZ but at the same time increased the amount of M-A constituent, thereby deteriorating CGHAZ toughness. It is believed that Al, Si, and free N that is uncombined with Ti retard the decomposition of austenite into pearlite and increase the carbon content in the last transforming austenite, thus increasing the amount of M-A constituent. Regardless of the amount of ferrite in CGHAZ, its toughness decreased linearly with an increase of M-A constituent in this experiment, indicating that HAZ toughness is predominantly affected by the presence of M-A constituent. When a comparison of the effectiveness is made between Al and Si, it showed that a decrease in Si content is more effective in reducing M-A constituents.


2016 ◽  
Vol 61 (3) ◽  
pp. 1723-1732 ◽  
Author(s):  
Weijuan Li ◽  
Shengshi Zhao ◽  
Hengyi Zhang ◽  
Xiaolong Jin

AbstractIn the present work, specimens prepared from coarse grained low carbon steel with different prestrains were baked and then, their bake hardening (BH) property and internal friction were determined. TEM was used to characterize the dislocation structure in BH treated samples. The measurements of internal friction in prestrained samples and baked samples were carried out using a multifunctional internal friction apparatus. The results indicate that, in coarse grained low carbon steel, the bake hardening properties (BH values) were negative, which were increased by increasing the prestrain from 2 to 5%, and then were decreased by increasing the prestrain from 5 to 10%. In the specimen with prestrain 5%, the BH value reached the maximum value and the height of Snoek-Köster peak was observed to be the maximum alike. With increasing the prestrain, both of the BH value and Snoek-Köster peak heights are similarly varied. It is concluded that Snoek-Köster and dislocation-enhanced Snoek peaks, caused by the interactions between interstitial solute carbon atoms and dislocations, can be used in further development of the bake hardening steels.


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