Hot Rolled Steel Common Defects and Control Strategies

Hot rolled coil (HRC) serves as a foundational material in modern industry, widely utilized in construction, automotive, shipbuilding, and energy sectors. Its quality directly determines the safety and reliability of the end products. However, production processes are prone to defects like pitting, edge cracks, and warpage, which not only affect aesthetics but may also lead to structural failures. Therefore, establishing a scientific quality control (QC) system identify and prevent is a critical stage for steel manufacturers.

Defect Analysis and Quality Control Strategies

1. Key Defect Types and Root Causes

· Pitting: Arises from high-temperature oxidation of mill rolls or residual scale fragmentation during rolling.

· Edge Cracks/Warpage: Results from uneven ductility at edges, misaligned rolls, or improper tension control.

· Decarburization: Surface softening due to oxygen exposure in annealing atmospheres, compromising hardness and wear resistance.

2. Quality Control Technology Systems

Detection Tools:

· Ultrasonic Testing (UT): Identifies internal flaws like laminations.

· Magnetic Particle Testing (MT): Locates surface-breaking cracks.

· Laser Profilometers: Monitor strip flatness to prevent warpage.

Process Optimization:

· Dynamic Descaling: Adjusts high-pressure water jet pressure/timing to reduce oxide scale residue.

· Roll Profile Management: Regular grinding and wear monitoring to minimize pitting.

· Tension Control: Closed-loop systems regulate coiling tension to minimize warpage.

Quality control in HRC production demands an end-to-end “prevent-detect-improve” framework. By pinpointing defect mechanisms (e.g., oxide scale entrapment linked to furnace conditions) and deploying targeted QC tools (UT/MT), manufacturers can significantly reduce waste.

References

1. Guidelines for Steel Processing (AISI, 2024)
2. Advances in Hot Rolling Technology (AlSTech, 2023)
3. ASM Handbook: Properties and Selection of Irons and Steels (ASM International, 2022)
4. Standard Method for Macroetch Testing (ASTM E381, 2023)
5. Environmental and Lean Production Practices in Steel Mills (Journal of Sustainable Metallurgy, 2024)