Identify the crack first
Casting or forging defects, quench cracks, grinding cracks and service damage require different responses. Analyse process records, location and appropriate inspection results; a photograph alone is not a final diagnosis.
Do not simply carry forward assumptions from an abnormal batch. Retain affected parts, heat identity and processing records so that changing parameters does not erase evidence.
What to check in cooling
Material and heated condition. Check composition, microstructure and heating against the validated process. Cooling adjustments do not replace investigation of original defects or unsuitable heating.
Section and local geometry. Holes, corners, thickness transitions and heavy regions create different cooling and stress conditions. One universal corner radius cannot solve every part.
Medium and working-fluid condition. Compare concentration, bath temperature, contamination and cooling curves. A refractometer reading alone does not fully describe cooling performance.
Loading and relative motion. Check shielding, part spacing, immersion orientation and liquid flow. Establish not only whether motion exists, but whether flow reaches the relevant locations.
Why internal temperature measurement helps heavy parts
Surface and core follow different temperature paths, as may thick and thin regions of one liner. Representative measurements locate the temperature intervals where differences occur. Combined with hardness and microstructure, they reduce trial and error based solely on appearance and experience.
Consider both quench cracking and fracture in service
High-chromium cast iron wear parts and Cr–Mo steel SAG liners also require fracture resistance in service. Quench cracks and service fracture are not the same diagnosis; specify when the problem was found.
How specialised quenchants can help
AR-HCCI serves high-chromium cast iron; AR-SAG serves Cr–Mo steel SAG liners and large parts. Each is available separately. Selection balances cracking resistance, wear and overall properties rather than universally seeking the lowest or highest cooling rate. Technical guidance and optional measurement are selected as needed.
Record conditions before comparing changes
Limit changes so their effects can be identified, and retain before-and-after material, loading, fluid and measurement conditions. After process changes, still complete the required crack, hardness and microstructure inspections.
Users determine subsequent tempering and transfer arrangements according to material and process requirements. One delay or tempering temperature does not suit all steels.
How to start a discussion
Start with the workpiece type, crack location and stage of discovery. Add available records later; drawings and test reports are not required for first contact.