These are critical for material traceability.
Heat Number (or Melt Number): A unique alphanumeric code assigned to a single, specific batch of molten steel produced in a steelmaking furnace (BOS or EAF). All material originating from this single melt shares an identical chemical composition. It is the primary traceability link back to the steelmaking process.
Batch Number (or Lot Number): A code identifying a specific quantity of finished products (angles) manufactured under uniform conditions. A batch typically consists of material from the same heat, rolled on the same production line, and undergoing the same processing (e.g., heat treatment, cutting) at the same time. One batch may contain multiple bundles but from the same heat.