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Heat Treat and Mechanical Testing

Heat Treat and Mechanical Testing. Approved for Public Release. Introduction:. Electric Boat Corporation uses metallic materials that need to have specific material properties. Mechanical Properties are determined at such processes as Heat Treat

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Heat Treat and Mechanical Testing

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  1. Heat Treat andMechanical Testing Approved for Public Release

  2. Introduction: Electric Boat Corporation uses metallic materials that need to have specific material properties. • Mechanical Properties are determined at such processes as Heat Treat • The properties are verified using testing techniques called out in the requirements Heat Treat & Mechanical Test Approved for Public Release

  3. Specific Heat Treat Process: • Heat Treat oven: • Time • Temperature • Cooling rates: • Air cool quench • Water quench • Calibration requirements Heat Treat & Mechanical Test Approved for Public Release

  4. Specific Heat Treat Process: Do you understand your process? CONTROLS MATERIAL PROPERTIES TEST RESULTS • Work 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) Heat Treat & Mechanical Test Approved for Public Release

  5. Heat Treat Failures: • Not meeting the mechanical property requirements (see controls) • Heat Treat procedure not followed • Test pieces to verify properties: • Insufficient number of test pieces • Incorrect size for the test sample • Samples taken from incorrect location Heat Treat & Mechanical Test Approved for Public Release

  6. All Material Requirements Invoked: • As part of the specific requirements • As part of the part number description • As a note on the drawing • In an Electric Boat Material Specification • In a Standard Clause • In an Engineering Report (ER) • Combination of the above Heat Treat & Mechanical Test Approved for Public Release

  7. Misinterpreting the Requirements Caused by: • Lack of familiarity with: • Material requirements • Test requirements • Heat treat requirements • Unclear/confusing requirements • Incorrect assumptions about testing Heat Treat & Mechanical Test Approved for Public Release

  8. Specific Material Requirements: Tensile (ASTM E8 or ASTM A370) • Tensile strength (psi or ksi) • Yield strength (psi or ksi) • Elongation (%) • Reduction in area (%) Heat Treat & Mechanical Test Approved for Public Release

  9. Specific Tensile Failures: • Improper Specimen size • Improper number of test specimens • Sample location from material improper Heat Treat & Mechanical Test Approved for Public Release

  10. Specific Material Requirements: Hardness Brinell test (ASTM E10) Rockwell A or B test (ASTM E180) • Minimum value • Maximum value • Range or values Heat Treat & Mechanical Test Approved for Public Release

  11. Specific Hardness Failures: • Testing not performed • Surface preparation improper • Correction factors for geometric shapes (convex or cylindrical surfaces) not taken Heat Treat & Mechanical Test Approved for Public Release

  12. 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) Heat Treat & Mechanical Test Approved for Public Release

  13. Specific Toughness Failures: • Charpy v-notch (wrong test temperature) Heat Treat & Mechanical Test Approved for Public Release

  14. Specific Material Requirements: Bend Testing • Bending the suitable sample to a specified radius • Ductility • ASTM E290 Heat Treat & Mechanical Test Approved for Public Release

  15. Specific Material Requirements: Bend Testing Bending the suitable sample to a specific radius (Wrong Bend Radius) Heat Treat & Mechanical Test Approved for Public Release

  16. Specific Material Requirements: Surface Test Surface treatment for wear/galling resistance- verified by hardness testing (called case hardening) • by carburizing or nitriding Heat Treat & Mechanical Test Approved for Public Release

  17. Heat Treat Certification Heat Treat & Mechanical Test Approved for Public Release

  18. Heat Treat Certification Heat Treat & Mechanical Test Approved for Public Release

  19. Heat Treat Certification Heat Treat & Mechanical Test Approved for Public Release

  20. Summary: • Process Controls → Material Characteristics → Test Results • Meet all required: • Material property requirements • Heat treat requirements • Changes need to be authorized by Electric Boat Heat Treat & Mechanical Test Approved for Public Release

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