1 Heat Treat and Mechanical Testing Approved for Public Release

2Heat Treat & Mechanical Test 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 Approved for Public Release

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

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

5Heat Treat & Mechanical Test 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 Approved for Public Release

6Heat Treat & Mechanical Test 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 Approved for Public Release

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

8Heat Treat & Mechanical Test 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

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

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

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

12Heat Treat & Mechanical Test 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

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

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

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

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

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

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

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

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