Hot Crack Susceptibility in Steel Slabs
Introduction
Steel slabs have been used industrially for centuries, with the process of tempering and reheating steel slabs becoming increasingly important over time. Steel slabs are rolled and tempered with a variety of surface treatments, including patches, grinding, heat treating, and other finishing processes. As the technology of steel-making continues to evolve, more sophisticated methods are being used to optimize the performance and quality of steel slabs. One of the most notable developments in steel-making is the focus on reducing hot cracking, which occurs when one material is placed in tension and experiences local failure due to fracture propagation. Hot cracking, also known as hot-shortness, occurs when steel slabs experience extreme levels of tensile stress and strain during the finishing process which facilitates crack formation and propagation. Hot cracking is one of the most significant limitations associated with steel slabs, as it is an extremely reliable defect that can significantly reduce the quality and performance of a material. The susceptibility of steel slabs to hot cracking is largely dependent on the chemical composition of the steel slab, its microstructure, and the nature of the surface treatments. This paper examines the hot cracking susceptibility of steel slabs and explores the techniques that are used to reduce or prevent hot cracking.
Hot Crack Susceptibility of Steel Slabs
The hot cracking susceptibility of steel slabs is influenced by several key factors. The chemical composition of the steel slab affects the propensity for hot cracking, as certain alloying elements are known to aid in preventing crack formation and propagation. For example, molybdenum and silicon are considered beneficial elements for hot cracking resistance. The microstructure of the steel slab also plays a major role in the hot cracking propensity of the material, as the microstructure can affect the local stress levels and the strain rate of the material during the finishing process. Additionally, surface treatments also play a role in preventing hot cracking, as surface treatments can be used to increase the internal compressive stress levels in the material and reduce the strain rate during the finishing process.
Various methods can be used to reduce or prevent hot cracking in steel slabs. One of the most effective prevention techniques is to reduce the tensile stresses in the steel slab by utilizing stress-relieving treatments such as normalizing, quenching and tempering, or multiple passes with a hot rolling system. Additionally, some steel companies have developed proprietary treatments which introduce additional compressive stresses on the surface of the material to further reduce the likelihood of hot cracking. Additionally, steel slabs can be surface-treated with a variety of patches, grind, or coatings which help reduce the amount of residual stress on the surface of the steel slab.
Conclusion
Steel slabs are widely used in industry, and due to their intricate craftsmanship, they are susceptible to hot cracking. Hot cracking is caused by excessive tensile stresses combined with fast working rates, and is a reliable defect that can significantly reduce the performance of the steel slab. As hot cracking is an inevitable defect of steel slabs, it is important to understand the susceptibility of steel slabs in order to reduce or prevent cracking during the manufacturing process. The hot cracking susceptibility of steel slabs is largely dependent on the chemical composition and microstructure, as well as the nature of surface treatments. Several methods can be utilized to reduce or prevent hot cracking in steel slabs, including stress-relieving treatments, surface treatments, and proprietary treatments.
