When sourcing round billets, you must prioritize chemical composition (carbon, manganese, silicon, sulfur, and phosphorus levels) to ensure the steel grade meets your specific application needs. Dimensional accuracy, particularly the diameter tolerance and straightness, is critical for downstream processes like seamless pipe production or forging. Additionally, verify the internal soundness through ultrasonic testing to ensure there are no subsurface cracks, blowholes, or non-metallic inclusions that could compromise structural integrity.