title = "Heat Treatment Quality Verification Methods"

content = """
Quality verification after heat treatment confirms that the required microstructure and mechanical properties were achieved, and that the process documentation is complete. At Ridgecrest Metalworks, the quality plan for each part specifies which verification tests are required, at what frequency, and what the acceptance criteria are.

Hardness testing is the primary in-process quality check after hardening, tempering, annealing, and case hardening. Rockwell hardness (HRC, HRB) is the most common shop-floor test: the operator uses a calibrated Rockwell tester, prepares the surface (minimum Ra 125 µin, free from scale and decarb), and makes the specified number of readings per part or per load. For carburized parts, surface hardness is checked on the part and through the case on a metallographic cross-section (measured in HRC or converted from Vickers HV). Brinell hardness (HB) is used for softer, as-annealed or normalized materials, checked with a calibrated ball indenter and optical measurement of the indent diameter.

Case depth measurement for carburized and nitrided parts requires preparation of metallographic cross-sections from process coupons (test pieces processed in the same load as production parts). The coupon is sectioned, mounted in bakelite, polished, and etched with nital (2–3% nitric acid in alcohol) to reveal microstructure. Effective case depth is measured as the depth to a specified hardness gradient using a microhardness indenter (Vickers HV0.3 or HV0.5) under a microscope.

Microstructural examination at 100× to 500× magnification verifies the expected microstructure: martensite in hardened steel, bainite in austempered parts, pearlite-ferrite in normalized steel. Decarburization, grain size, and carbide distribution are assessed per applicable specifications. Intergranular oxidation (IGO) in the carburized case is evaluated where required.

Process coupon tensile and impact tests may be required for aerospace or structural components to verify mechanical properties. Coupons are machined from material processed in the same heat treat load as production parts.

Verification failures require quarantine of the affected lot, root cause investigation, corrective action, and dispositioning of parts (re-heat treat if possible, scrap if not). All nonconformances are documented in the corrective action system.
"""

version = "0.0.1"
