Heat Treat andMechanical TestingApproved for Public Release

Introduction:Electric Boat Corporation uses metallicmaterials that need to have specific material properties.Mechanical Properties are determined at such processes as Heat TreatThe properties are verified using testing techniques called out in the requirements

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Specific Heat Treat Process:

Heat Treat oven:TimeTemperatureCooling rates:Air cool quenchWater quenchCalibration requirementsApproved for Public Release

Specific Heat Treat Process:

Do you understand your process?CONTROLSMATERIAL PROPERTIES TEST RESULTSWork backward from the results. Study the process controls that gets you the range of results that are optimal for the customer. Adjust the controls to match. Test to verify the results.Study using Design of Experiments (DOE)Control the process by Statistical Process Control (SPC)Approved for Public Release

Heat Treat Failures:Not meeting the mechanical property requirements (see controls)Heat Treat procedure not followedTest pieces to verify properties:Insufficient number of test piecesIncorrect size for the test sampleSamples taken from incorrect locationApproved for Public Release

All Material Requirements Invoked:As part of the specific requirementsAs part of the part number descriptionAs a note on the drawingIn an Electric Boat Material SpecificationIn a Standard ClauseIn an Engineering Report (ER) Combination of the above Approved for Public Release

Misinterpreting the Requirements Caused by:Lack of familiarity with:Material requirementsTest requirementsHeat treat requirementsUnclear/confusing requirementsIncorrect assumptions about testing

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Specific Material Requirements: Tensile(ASTM E8 or ASTM A370)Tensile strength (psi or ksi)Yield strength (psi or ksi)Elongation (%)Reduction in area (%)Approved for Public Release

Specific Tensile Failures:Improper Specimen sizeImproper number of test specimensSample location from material improperApproved for Public Release

Specific Material Requirements: Hardness Brinell test (ASTM E10)Rockwell A or B test (ASTM E180)Minimum valueMaximum valueRange or valuesApproved for Public Release

Specific Hardness Failures:Testing not performedSurface preparation improperCorrection factors for geometric shapes (convex or cylindrical surfaces) not takenApproved for Public Release

Specific Material Requirements: Toughness Verified by impact testing and fracture toughness testing Charpy v-notch (most common, ASTM E23, size and temperature)Dynamic tear testing (similar to Charpy)Fracture toughness test (ASTM E1820, more sophisticated than above)Approved for Public Release

Specific Toughness Failures:Charpy v-notch (wrong test temperature)Approved for Public Release

Specific Material Requirements: Bend Testing Bending the suitable sample to a specified radiusDuctility ASTM E290Approved for Public Release

Specific Material Requirements: Bend Testing Bending the suitable sample to a specific radius (Wrong Bend Radius)Approved for Public Release

Specific Material Requirements: Surface Test Surface treatment for wear/galling resistance- verified by hardness testing (called case hardening) by carburizing or nitridingApproved for Public Release

Heat Treat CertificationApproved for Public Release

Heat Treat CertificationApproved for Public Release

Heat Treat CertificationApproved for Public Release

Summary:Process Controls Material Characteristics Test ResultsMeet all required:Material property requirementsHeat treat requirementsChanges need to be authorized by Electric BoatApproved for Public Release