Control of Transverse Corner Cracks on Low-Carbon Steel Slabs

Self Cite

In the current article, a method based on analysis of the microstructure combined with numerical simulation of the temperature field of a continuous casting slab is proposed to eliminate the transverse cracks occurred in slab corners. The microstructures near the cracks will be varied as the phase‐transformation conditions change. Thus, the cracking temperature range can be effectively estimated by analyzing the microstructures near the cracks. The different behaviors of microstructures near cracks in three conditions are presented and discussed. These behaviors include the following: the decarburization layer is symmetrically distributed on both sides of the cracks; the microstructures are refined near the cracks; the cracks “open” the ferrite along the austenite grain boundaries, which results in the ferrite being symmetrically distributed on both sides of the cracks. The variation of the slab corner temperature during a continuous casting process is calculated and discussed. Then, a secondary cooling adjustment scheme is proposed to eliminate the occurrence of transverse corner cracks on the slab surface. Results from industrial practice show that the method can effectively avoid the generation of slab surface cracks without damage to the internal quality of the slab. The method can also be applied to other studies of crack control.

Section: Numerical Simulation Of the Slab Temperature Field During Comentioning

confidence: 90%

Section: Numerical Simulation Of the Slab Temperature Field During Comentioning

confidence: 99%

Section: Numerical Simulation Of the Slab Temperature Field During Comentioning

confidence: 99%

See 1 more Smart Citation

A Method to Control the Transverse Corner Cracks on a Continuous Casting Slab by Combining Microstructure Analysis with Numerical Simulation of the Slab Temperature Field

Yang

Zhang

Lai

et al. 2018

Self Cite

“…Some investigations were done based on the plant slab or casting. However, the tensile test samples were extracted with their axes either along the casting direction or perpendicular the casting direction, either extracted in the slab corner or in the slab center, or no explanation at all …”

Section: Introductionmentioning

confidence: 99%

“…Some investigations were done based on the plant slab or casting. However, the tensile test samples were extracted with their axes either along the casting direction [15,22] or perpendicular the casting direction, [23] either extracted in the slab corner [24] or in the slab center, [16] or no explanation at all. [25] Although much work had been done to study the steel hot ductility behavior, there was no study to reveal the effect of sampling positions and sampling directions on hot ductility behavior.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sampling Locations on Hot Ductility of Low Carbon Alloyed Steels

Zhang

Wang

2018

Influences of steel composition and cooling rate on the steel hot ductility have been studied comprehensively. Microstructural examination reveals chill, columnar, columnar to equiaxed transition (CET) and equiaxed zones in the slab cross‐section from surface to center. Little paper reports the effect of tensile test specimens sampling position and sampling direction from the slab on the hot ductility behavior. In the current study, the hot ductility of specimens extracted from different sampling positions and different directions is detected using a thermal simulator Gleeble 1500 (Dynamic Systems, Inc., Poestenkill, NY) to determine the brittle temperature range of the steel. In addition, investigations are made currently to reveal the effect of the strain rate and holding temperature on the steel hot ductility. Some conclusions can be made in the current study: 1) the sampling position has much influence on the hot ductility behavior and the specimens extracted from the columnar zone performs the best hot ductility; 2) the hot ductility improves observably with the increasing of the strain rate, as a result of the dynamic recrystallization and dynamic stain hardening; 3) the increasing of the holding temperature performs a negative effect on the steel hot ductility.

Hot Ductility and Fracture Phenomena of Low‐Carbon V–N–Cr Microalloyed Steels

Liu

et al. 2019

The hot ductility of low‐carbon V–N–Cr microalloyed steel is studied using a thermomechanical simulator. The steel is solution treated at 1350 °C and cooled at 15 °C s−1 to the test temperature in the range of 650–1200 °C. Next, they are strained to failure at a strain rate of 4 × 10−3 or 4 × 10−2 s−1, and ductility troughs are obtained. The results reveal a ductility trough in V–N–Cr steels in the range of 650–900 °C with a minimum reduction in area (RA) value of 13.5 % at 800 °C and strain rate of 4 × 10−3 s−1. The occurrence of dynamic recrystallization from 950 to 1200 °C has a substantial contribution to high ductility and on the formation of film‐like ferrite at prior austenite grain boundaries. The fracture mechanism changes from intergranular to highly ductile microvoid coalescence in the temperature range of 800–1200 °C and at a higher strain rate. Ductility loss in the V–N–Cr steel is caused by the presence of a high density of VN and/or V(C,N) precipitates, which are linearly present within the matrix, and a small number of random precipitates are present at the boundary.