Non-Destructive Testing
Meaning ~ Inspection techniques that evaluate the internal structure of manufactured materials without causing damage represent a formal verification category.
Astm E446
Meaning
Quality assessment tools for thin-walled steel castings use a set of reference radiographs to categorize the nature and size of internal discontinuities. This document astm e446 focuses on sections that are two inches thick or less. It defines five categories of defects including inclusions and cracks.
Foundries use these plates to verify that their casting process produces parts that meet the buyer’s specifications.
Defect Severity
Graduated levels within each category allow for the precise description of the casting’s internal state. The astm e446 plates show how porosity looks at various densities and sizes. A buyer might accept level two for a structural frame but demand level one for a valve body.
Inspection Standard
Verification of the part’s soundness occurs during the final quality control phase. The astm e446 reference films are unique to the material and thickness they represent. Using the wrong set of references leads to an invalid inspection report and project delays.
Production Risk
Inadequate control of the pouring temperature often results in gas holes that show up on the radiograph. Following the guidelines in astm e446 helps the manufacturer identify when a process is drifting out of control. Repairs to the casting are only permitted if the severity of the original flaw falls within specific limits.
Costs for rework or replacement escalate quickly when the defects are discovered late in the manufacturing cycle.