In the process of smelting and rolling carbon steel, there are often deficiencies due to equipment, procedures, or operational errors. These issues include surface defects like scabs, cracks, residual pores, delamination, white spots, segregation, non-metallic inclusions, looseness, and banding structures. Scabbing A metal or non-metallic lump on the steel's surface that isn't fully fused with the base material. Some parts may be partially attached to the base, forming a tongue-like shape, while others are entirely detached and flaky. These detached flakes can fall off during processing, leaving pits behind. Scabbing caused by steelmaking (casting) usually involves visible non-metallic inclusions to the naked eye. When it occurs during rolling, it’s commonly referred to as "scale," with the iron oxide being the typical underlying issue. The primary causes of scabbing during steelmaking (casting) are: (1) Failure to implement splash protection measures during the casting of the top ingot or applying excessive force when casting the bottom ingot, leading to splashing and subsequent scabbing. (2) Poor performance of the lower ingot slag or unclean molds that haven’t been properly dried, resulting in surface or subsurface inclusions, bubbles, or heavy skins on the steel ingot (or continuous casting slab). (3) Severe damage to the mold walls or excessively high casting temperatures, which lead to crown formation and sticking to the mold, eventually forming scabs during rolling or forging. Scabbing during rolling happens because: (1) Defective rolls (rails) or improperly aligned guide devices prior to finishing create protrusions, ears, or scratches in the rolled piece, which form scabs upon re-rolling. (2) Excessive flame cleaning of slabs or incomplete removal of residues causes foreign objects to fall onto the slab and get rolled into scabs. These scabbing defects directly impact the appearance and mechanical properties of the steel. Finished steel must not have any scabs. Any knotted areas can be ground and repaired, but the dimensions post-grinding should still adhere to standards. To minimize and eliminate scabs, improvements in steelmaking and rolling processes are essential, along with focusing on the surface defects of the billets or thoroughly removing the skin. Cracks Cracks come in various forms and can arise from multiple causes, such as splitting, transverse cracking, fissures, hairline cracks, brittle fractures, rolling-induced fractures, or shear fractures. Almost every stage of steel processing, from initial smelting to deep processing, poses potential risks for cracking. (1) Steelmaking High sulfur and phosphorus content in steel leads to reduced strength and plasticity. Casting temperatures that are too high, excessively rapid casting speeds, incorrect casting flows, poorly designed molds, insufficient or uneven cooling, and defects in the ingot mold or thermal insulation cap during the solidification process can all contribute to thin or localized stresses in the chilled layer. Additionally, poor performance of protective slag, mold flux, and other casting operations can result in poor surface quality and the formation of cracks on the steel. Hexagon Punch,Carbide Screw Punch Die,Tungsten Carbide Punching Pin,Tungsten Carbide Punch Hebei Yuanyue Trading Co.,Ltd , https://www.hbyuanyue.com