Prediction Of Cracks Of The ContinuouslyCast Carbon-steel Slab (original) (raw)
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On The Possibilities Of Verifying The CrossCracking Mechanism In The Con-cast Steel Slab
WIT transactions on engineering sciences, 2004
This contribution (which follows the previous articles [1,2]) tries to verify the hypothesis on the initiation and propagation of the cross crack by means of behaviour in tensile tests with the con-cast slab of the same basic chemical composition in the range of temperature moving from 25°C to 1450°C. The tensile tests were made on 18 test bars at suitably chosen temperature differences and gradually led to the tension ruptures of the bars under exactly defined conditions. Simultaneously, the roughness of the resultant rupture surface depending upon the temperature was studied in detail. Thus relations between the roughness of the rupture surface, tension force, work to rupture and contraction with the test bars at the given range of temperature were determined. On the basis of the comparison of the rupture surfaces of cross cracks found in the study [2] and the rupture surfaces obtained at the given interval of test temperatures in the course of this study, properties of material o...
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A new criterion for internal crack formation in continuously cast steels
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2000
To estimate the cracking condition in continuously cast steels, a new model for critical fracture stress given from the measured critical strain has been proposed, which can take into account the brittle temperature range and strain rate. The effects of brittle temperature range and strain rate on critical strain for internal crack formation were analyzed. When the brittle temperature range and strain rate were increased, the possibility of internal crack formation increased due to the decreasing critical strain. To describe the thermomechanical property model of the mushy zone between zero strength temperature (ZST) and zero ductility temperature (ZDT), the yield criterion for porous metals, which can take into account δ/γ transformation, was used. Using the fitting equation for the measured critical strain and the microsegregation analysis, the thermomechanical behavior of the mushy zone could be successfully described by the proposed model, which incorporates the effects of microsegregation of solute elements and δ/γ transformation on hot tear during solidification at the given range of steel compositions and strain rates. A cracking criterion based on the difference of deformation energy in the brittle temperature range is proposed to explain the cracking phenomenon of whole carbon range.
Analysis of Crack Formation in the Casting: A Review
IAEME PUBLICATION, 2020
This analysis discusses the various types of internal and surface cracks that may form during steel casting continuously. Due to the high Thermal structural properties of the materials are analysed and the pressures of the solidifying shell are measured as well as functioning and metallurgical influences considered to impact the development of crack for each crack type. This method shows the importance of two low ductility zones in steel. There is one region above 1340 ° C and it is possible that all internal cracks and longitudinal surface cracks are formed. The other regions ranges from 700 to 9000 C and is correlated with the presence of soluble aluminium, niobium and vanadium. Lateral surface cracks can be associated to the other latter zone in slabs. Combined with an understanding of the stresses produced by continuous casting, this knowledge makes it possible to propose crack formation mechanisms and relate them to operational and metallurgical variables.
Metals and Materials International, 2010
The solidification path and contraction generated during the solidification of three carbon steels were studied. Two of the carbon steels were of hypo-peritectic chemical composition, with 0.11 % C and 0.15 % C, while one of the carbon steels were hyper-peritectic with 0.16 % C. The steels with 0.11 % C and 0.16 % C solidified as expected due to their chemical composition. In contrast, the chemically hypo-peritectic steel with 0.15 % C solidified as hyper-peritectic steel, which was associated with the microsegregation of Mn. For the steel exhibiting a hypo-peritectic solidification path, peritectic transformation occurred at solid fraction values higher than 0.9, where it was assumed that the contraction generated in the mushy shell cannot be fed by the liquid. However, for steels exhibiting a hyper-peritectic solidification path, peritectic transformation began at solid fraction values lower than 0.9, where the contraction generated by the peritectic transformation was partly fed by the liquid. Hence, the highest cracking susceptibility was associated with the hypo-peritectic solidification mode.
Development of an analytical model to predict the microstructure of continuously cast steel slabs
Steel Research, 2000
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Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2020
The ductility drop and decrease in strength that lead to crack formation during continuous casting of steel is typically investigated by means of the hot ductility test. In this study, hot ductility tests are performed by using a thermo-mechanical Gleeble system to simulate the deformation of steels at high temperatures and low deformation rates similar to those during continuous casting. Thus, temperature was varied between 600 and 1000 � C while strain rates covered a range from 0.001 to 0.1 s 1. Tests are carried out to identify the temperature range at which the steel is susceptible to crack formation as well as the effect of strain rate. Characterization of fractured surfaces and phase transformation after thermo-mechanical tests are conducted in the SEM and Optical Microscope. The combination of these techniques makes possible to formulate cracking mechanisms during hot processing which show critical strain for failure at temperatures between 700 and 900 � C based on the convergence of three different criteria: I) Reduction of area, II) True fracture strength-ductility and III) True total energy. This approach provides a better understanding of crack formation in steels at the high temperatures experienced during continuous casting. This information is key to productivity losses and avoid defect formation in the final cast products.
The research investigated the mechanical behavior of samples of steel rods obtained from three selected Steel Rolling Companies in South Western part of Nigeria. This was done by carrying out some mechanical tests such as tensile, impact and hardness as well as microstructural examination.Four sets of 16 mm steel rod samples were collected from Tiger steel industries, Phoenix steel and Oxil steel Industies, all located in South West Nigeria, The chemical composition was carried out using a Spectrometer (EDX3600B). Afterwards, different samples were prepared, cut and machined according to ASTM standards dimensions of tensile and impact tests as well as hardness test from which their Ultimate tensile Strength, Yield strength, Percentage elongation, Impact strength and Brinell hardness number were obtained and compared to three standards (ASTM A706, BS 4449 and Nst 65-Mn). Their microstructures were also examined and analyzed.The results showed that the Ultimate tensile strength for the samples from Oxil steel, Phoenix Steel and Tiger steel were 661 N/(mm) 2 , 653 N/(mm) 2 and 631 N/(mm) 2 respectively while their hardness values were 150 BHN, 178 BHN, 214 BHN respectively. The sample from Tiger steel and Oxil Steel had the finest and most coarse microstructure respectively. In conclusion, it was observed that the results of the sample analysis from the three selected Steel Rolling Companies conformed to most of the standards except the sample from Tiger steel which had a high hardness value compared to the standard.
Analysis of a Transversal Crack in a Steel Slab
Materials Science Forum, 2008
This paper deals with an analysis of the possible causes of a transversal crack in a steel slab with a l300×l45 mm cross-section using results from two models. Samples were taken from and around the crack in order to analyze the concentration (i.e. chemical heterogeneity) of the relevant elements. Simultaneously, the concentration of elements at the surface of the crack was measured after the crack was opened. The chemical heterogeneity of elements was analyzed with the aid of the JEOL JXA 8600/KEVEX analytical equipment. The measurement results were processed using mathematical statistics procedures. The results proved that there was an internal crack initiating immediately below the curve of the solid-state temperature and consecutively propagating.