title = "Production Hardness Testing: Portable and Bench Methods"

content = """
Hardness testing verifies that heat treatment processes have achieved the required material hardness. At Ridgecrest Metalworks, hardness testing is performed as part of incoming material inspection, post-heat treatment verification, and periodic process audits. Both bench (laboratory) and portable hardness testers are used depending on part size and location.

Rockwell hardness testing (ASTM E18) is the most common production method for steel. The test uses a diamond cone indenter (Brale, for HRC scale) or ball indenter and measures hardness from the depth of indentation under a major load. The HRC (Rockwell C) scale is used for hard steels (heat treated, case hardened) above approximately 20 HRC; HRB (Rockwell B) is used for softer steels and non-ferrous metals. Rockwell testing is fast (result in seconds), the indentation is small, and the operator reads directly from the instrument display without measuring indentation size. Bench Rockwell testers accommodate most component sizes; the part must sit stably on the anvil with the test surface perpendicular to the indenter.

Brinell hardness testing (ASTM E10) uses a hardened steel or carbide ball indenter under a large load (typically 3000 kgf for steel). The indentation diameter is measured optically using a calibrated Brinell microscope. Brinell is preferred for coarse-grained materials like castings and forgings where the large indentation averages over microstructural variation. HB values correlate to ultimate tensile strength (approximately UTS MPa = 3.45 × HB), which is useful when hardness is used as a proxy for strength verification.

Vickers hardness testing (ASTM E92) uses a square pyramid diamond indenter. Diagonal length of the square indentation is measured optically. Vickers covers the full hardness range and is the most precise method for case depth measurement, thin case layers, and small parts. Microhardness (HV0.1–HV1) is used for measuring individual microstructural constituents or plating layers.

Portable hardness testers: Rebound (Leeb) testers (per ASTM A956) are used on large parts or structures where removal to a bench tester is impractical. A spring-loaded impact body strikes the surface; the ratio of rebound to impact velocity gives a Leeb hardness value, which is then converted to Rockwell or Brinell using tables. Results are less precise than bench methods but are acceptable for verification when bench testing is impractical.

Calibration of hardness testers uses certified reference blocks (Rockwell) or reference blocks and ring gauges (Brinell). Three readings on the reference block are taken before each test session; if the average deviates beyond the instrument tolerance, calibration or service is required.
"""

version = "0.0.1"
