title = "Ultrasonic Testing (UT) for Internal Defect Detection"

content = """
Ultrasonic Testing (UT) uses high-frequency sound waves to detect and characterize internal and surface defects in materials. At Ridgecrest Metalworks, UT is applied to plate and bar stock (incoming inspection for laminations), weld seams (internal lack of fusion and porosity), and large forgings.

A piezoelectric transducer (probe) converts electrical energy into ultrasonic pulses, typically at frequencies of 2–10 MHz for steel. The sound travels through the material and reflects from back surfaces, internal boundaries, and defects. Reflected signals are displayed on an A-scan oscilloscope (amplitude vs. time), from which the depth and relative size of reflectors can be determined using the material's sound velocity.

Probe types:
- Normal (compression wave) probes: Sound travels perpendicular to the surface; used for detecting laminations, inclusions, and porosity in plate and forgings.
- Angle probes (shear wave): Sound travels at 45°, 60°, or 70° to the surface; used for weld inspection, where the weld geometry prevents normal beam access.
- Dual-element (twin crystal) probes: Separate transmit and receive crystals; reduced dead zone near the surface; used for near-surface defect detection and thickness measurement.

Weld UT procedure (per ISO 17640):
1. Surface preparation: Scan surface must be smooth (Ra ≤ 6.3 µm) and free of scale and spatter that would obstruct probe contact.
2. Coupling: Couplant gel or oil is applied between probe and surface to ensure sound transmission.
3. Calibration: Instrument is calibrated using a reference block with known reflectors (SDH — side-drilled holes or FBH — flat-bottom holes) to establish the DAC (Distance-Amplitude Correction) curve or TCG (Time-Corrected Gain) curve.
4. Scanning: The probe is moved systematically across the weld at specified index points and scan patterns to ensure full weld volume coverage.
5. Interpretation: Reflections are assessed against the DAC curve and compared to acceptance levels per the applicable standard (e.g., ISO 11666 for welds).

Phased Array UT (PAUT) uses an array of transducer elements electronically controlled to steer and focus the beam, enabling faster inspection and better visualization through S-scan (sectorial scan) images. PAUT is increasingly used at Ridgecrest for efficient inspection of complex weld geometries.
"""

version = "0.0.1"
