Ultrasonic Testing (UT) Reject Analysis Project

During my internship at JSW Steel USA in Summer 2024, I led an investigative project focused on reducing ultrasonic testing (UT) rejections by identifying root causes through metallurgical analysis and process data mining. The project sought to improve product quality by minimizing internal defects and increasing process consistency.

Data Insights:

• UT rejection rate increased with plate thickness.
• Higher tundish superheat temperature (especially from 3rd tundish) correlated with increased rejection rates.
• ASTM A572-50 steel was disproportionately represented in UT hold data failures.

Key Investigations:

• Inclusion Analysis: SEM/EDS microscopy revealed Manganese Sulfide stringers, Aluminum Oxides, and Niobium-based inclusions contributing to crack initiation and UT failures.
• Root Cause Analysis: Poor calcium treatment and inconsistent caster operation were identified as possible contributors to inclusion formation.
• Sample Focus: ASTM A572-50 steel exhibited the highest reject rates, prompting detailed analysis of its chemistry and casting parameters.

Results:

• Calcium Treatment: Evidence of Manganese Sulfide stringers implied insufficient or ineffective calcium treatment at the caster.
• Scrap/Casting Powder: SEM-EDS analysis revealed trace inclusions of Lead, Magnesium, and Zirconium, suggesting possible contamination from scrap metal or casting powder.
• Process Recommendations: Recommended optimizing superheat control in tundish operations and reducing maximum plate thickness to improve UT pass rates.

Tools & Skills Gained:

• SEM/EDS microscopy and inclusion identification
• UT data correlation with process variables (superheat, thickness, grade)
• Failure analysis and root cause identification

This project enhanced my ability to diagnose metallurgical defects using microscopy and data analytics. It also deepened my understanding of how upstream casting practices influence downstream product quality in steel manufacturing.