What Can Go Wrong With Air Bubble Prevention in Steel Forging Billets-

https://weld-quality-research.scriblorax.com/posts/key-steps-for-weld-repair-rechecks-in-pressure-vessel-fabrication

What Can Go Wrong With Air Bubble Prevention in Steel Forging Billets? Billets may be thick and can contain grain-related ultrasonic noise. Air bubbles can block the sound path and create missing or weak signals