Document Type : Research Article

Authors

• Mirreza Forogh ¹
• Reyhaneh Yazdekhasti ²
• Amir Gorji ³
• Ali Ashrafi ¹

¹ Isfahan University of Technology, Department of Materials Engineering, Isfahan, Iran

² Isfahan University of Technology, Department of Materials Engineering, Isfahan,Iran

³ Esfahan's Mobarakeh Steel Company , Isfahan, Iran.

Abstract

The integrity of steel pipes is crucial for their application in petrochemical industries and refineries. Given the corrosive nature of the working environment containing sour gasses, the pipes must possess the ability to withstand pressure and temperature, resist corrosion, endure fatigue and comply to safety and environmental regulations. A significant challenge in steelmaking of distinctive steel products, especially high-strength low-alloy steels, is the segregation of carbon, sulfur, manganese, and other elements within the slab's core. Additionally, the solidification process in the slab could leads to the concentration and buildup of shrinkage cavities in the middle thickness of the slab. The Baumann test is a crucial examination in steelmaking process for manufacturing of the pipes and pressure vessels since it verifies the quality of the products. Mannesmann pipes are categorized differently according to this test. In the current research, the microstructure, location and type of defects, has been investigated and the degree of segregation and the shrinkage holes in the slab's cross-section have been studied. The results obtained revealed that the aggregation of alumina and manganese sulfide inclusions were the primary factors contributing to the rejection of Baumann test. The investigations have been revealed that by simultaneously controlling the alumina impurity and using the best practice of secondary cooling, and employing the soft reduction technology, the problem mentioned above could be entirely resolved.

Keywords

• HSLA steels
• Bauman test
• soft reduction
• segregation
• inclusion

Main Subjects

• Corrosion and surface engineering