The Formation and Occurrence of Non-Metallic Inclusions of Si-Doped Steel during Continuous Casting

2011 ◽  
Vol 479 ◽  
pp. 13-21 ◽  
Author(s):  
Dong Yih Lin ◽  
Sheng Min Yang

Inclusion in steel material plays a decisive role on the purity of steels that becomes more important in the energy critical age. This study was focused on the number and morphology of inclusions with different cooling rate in the continuous casting process. A low carbon steel with 3.36 wt% silicon content was used as test material, which was soaked at 1100°C, 1250°C and 1400°C for 2 hours. The analyzed results of microstructure and chemical compositions showed the inclusions were not dissolved into matrix but formed as compounds like oxide, sulfide, and nitride after reheating at 1100°C. However, the inclusion size and average number possessed increasable trend, compared to as-cast sample. Manganese sulfide began to be dissolved into matrix by reheating at 1250°C. Some evidences showed the dissolution of aluminum nitride under the reheating at 1400°C. The inclusion size varied from 8 μm to 3 μm, and average number decreased with increasing soaking temperature.

2016 ◽  
Vol 61 (4) ◽  
pp. 2051-2056 ◽  
Author(s):  
G. Kwinta ◽  
S. Kara ◽  
B. Kalandyk ◽  
R. Zapała ◽  
P. Pałka

Abstract The exposed selvedge layers in slabs cast by the continuous process should be free from surface defects, which in most cases appear in the form of cracks on the casting surface and run to its interior. In addition to the parameters of the casting process, the occurrence of such defects depends on the chemical composition of cast steel, on the segregation of surface active elements and formation of the precipitates of carbides, nitrides and other phases. Due to the frequent occurrence of defects in corners of the slabs, non-destructive testing was performed on the mechanically cleaned surfaces of slabs. The test material was low-carbon API(American Petroleum Institute API 5L standard) steel micro alloyed with Nb and Ti designed for the production of pipes to handle gas, oil and other liquid and gaseous fuels. Despite the use of different methods of inspection, i.e. ultrasonic, magnetic particle and penetrant, cracks were not traced in the examined material. Then, from the corners of the examined slabs, specimens were cut out for metallographic examinations. The main purpose of these examinations was to disclose the presence of possible cracks and micro cracks on the surfaces transversal and longitudinal to the direction of casting. At the same time, studies were conducted to establish the number and morphology of non-metallic inclusions in selvedge layers of the slab corners and axis. Additionally, hardness of the slabs was measured. The conducted studies revealed only some minor differences in the slab hardness along its axis (130 ÷ 135 HB) and in selvedge layers (120 ÷ 123 HB).


2015 ◽  
Vol 1089 ◽  
pp. 315-318
Author(s):  
Qi Chun Peng ◽  
Li Deng ◽  
Jia Lin Song ◽  
Xi Song Sheng ◽  
Pin Tuan Deng

According to ULCS production practice in domestic steel,in combination with laboratorial data, this paper analyzes the influence factors of ULCS carbonization. The statistical results shows that carburization of ultra-low carbon steel is affected by mold flux、continuous casting process and refractory,and some corresponding control measures are put forward.


2015 ◽  
Vol 60 (4) ◽  
pp. 2927-2932
Author(s):  
J. Pieprzyca ◽  
T. Merder ◽  
M. Saternus

The way and speed of steel flux flowing into mould of continuous casting (CC) machine belong to the important parameters characterizing the steel continuous casting process. Such flux causes determined kinds of steel circulation, which together with simultaneous steel crystallization influence the creation of ingots primary structure and quality of its surface. The article presents the results of modelling research which aim was to determine the optimal location of submerged entry nozzle in square moulds (130 x 130 mm and 160 x 160 mm) of CC machine. Such a research was carried out for two different grades of steel (low-carbon steel and high-carbon steel), which feature different parameters of casting.


2012 ◽  
Vol 57 (1) ◽  
pp. 355-361 ◽  
Author(s):  
K. Sołek ◽  
L. Trębacz

Thermo-Mechanical Model of Steel Continuous Casting Process In the paper a numerical model of heat and mass transfer in the mould zone in the steel continuous casting technology was presented. The model has been developed using ProCAST software designed for simulation of casting processes. It allows to determine temperature and stress distribution in continuous castings in order to optimize the most important process parameters. In this work calculations were executed for low carbon steel grades casted in the industry. In the simulations the real rheological properties measured in the experimental work and the boundary conditions determined on the basis of the industrial data were used.


Author(s):  
Aleksander Siwek

AbstractThis paper presents a numerical model of the laser welding of steel, taking into account the heat and mass flows, as well as thermal effects associated with phase transformations. It was assumed that the heat source is a laser with a symmetrical power distribution of the TEM10 beam in two welding condition variants: a stationary heat source and a source moving at a constant speed along the sample. After reaching the melting temperature, the movement of the liquid phase was forced by the Marangoni effect acting on the surface of the welding pool. For the laser power applied, the surface of the welding pool was assumed to be flat. It was proposed an algorithm for the forecasting of the phase changes during heating and cooling. Diffusive phase transformations during cooling were modelled using Johnson-Mehl-Avrami-Kolmogorov (JMAK) equations. Diffusionless transformations occurring when cooling rates exceed the critical ones were modelled using Koistinen-Marburger (KM) equations. Calculations were made for a rectangular sample welded in air and cooled spontaneously in the atmosphere. The boundary conditions were simulated assuming a constant coefficient of heat exchange and radiation to the environment. The start and end time of the changes occurring in the cooling phase were calculated based on the average cooling rate in the temperature range 800–500°C (v8/5). The model was tested for the test material: S355J2 steel.


POROS ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 111
Author(s):  
Tumpal Ojahan Ojahan ◽  
Miswanto Miswanto Miswanto ◽  
Slamtt Sumardi Sumardi

Fueled by a rise in food needs as beef and oil into basic commodities has been consumed by thepublic, has lead the increasing of waste the cows and coconut shell. The main ingredient used in thisresearch is a waste product from cow bones and from the remains of the coconut shells from which no orhousehold wastes, that can be processed into charcoal. The purpose of this research which is to enhanceeconomic value of waste from cow bones and coconut shells using combustion pyrolysis system beingcharred (fixed carbon) to produce good quality charcoal, to find out the extent of the temperature used andthe composition of charcoal. The process used in this research is pack carburizing with cow bones andcoconut shell as the media at the temperature 950oC, time detention three hours with variations compositioncharcoal. It can be concluded that charcoal bone across his cattle and charcoal coconut can be used as asource of carbon that might improve the force and hardness in the material carbon steel low (low carbonsteel). The process of pack carburizing can increase the value of % C, against low carbon steel material.


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.


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