Irregularly shaped voids caused by a lack of adequate molten metal to feed the casting as it cools.
The standard serves as an official adjunct to hardware-based inspection. The actual physical adjunct package consists of reference radiograph film plates housed in protective cardboard frames. Inspectors cross-reference these physical film plates—or their equivalent digital reference images—directly against production X-ray films to determine whether a part passes or fails. The Eight Severity Levels of Discontinuities
The allowable level is determined by the "Class" of the casting (e.g., Class A, B, C, or D), dictated by the engineering design requirements and the component's operational risk. Deciphering "PDF Repack" in Industrial Documentation
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The original ASTM E155 was designed for . However, with the shift to digital detector arrays (DDA) and computed radiography (CR), the standard has been updated to allow digital comparison, provided:
Entrapped debris that appears on radiographs differently based on its density relative to the alloy. Key Specifications for Porosity Levels
: Covers castings with thicknesses up to 2 inches (51 mm). Irregularly shaped voids caused by a lack of
Note: For gas porosity specifically, quantification of flaw density becomes increasingly difficult for Levels 5 through 8 and often requires discussion between the manufacturer and the purchaser. Documentation & Purchasing Standard Content:
ASTM E155 remains an indispensable tool for maintaining safety and reliability in aluminum and magnesium casting supply chains. By establishing a clear visual scale from Levels 1 to 8, it removes ambiguity between foundry production teams and end-user quality inspectors. When implementing these metrics, ensure your engineering team is backed by certified NDT personnel and authentic, calibrated reference standards to guarantee structural compliance.
Many professionals confuse ASTM E155 with other documents. Here is a quick comparison: However, with the shift to digital detector arrays
The standard uses graded, film-based reference images. These images allow inspectors to compare a production X-ray against a set of known severity levels to determine if a casting passes or fails.
The grading scale is straightforward:
Contains some, but minor, porous spots or distributed gas porosity.
By organizing the severity levels (1 through 5), differentiating gas from shrinkage porosity, and creating a searchable, high-contrast reference, you reduce interpretation errors, speed up inspection times, and ensure consistent acceptance decisions.
A typical engineering drawing will specify the allowable defect level using a notation such as:
