EFFECT OF WELD DISCONTINUITIES ON THE MECHANICAL PROPERTIES OF ARMOR

WELDED JOINTS INVARIABLY CONTAIN IMPERFECTIONS OR DISCONTINUITIES. AS NONDESTRUCTIVE EVALUATION TECHNIQUES IMPROVE MORE OF THESE DISCONTINUITIES ARE DETECTED. IF ARBITRARY ACCEPTANCE CRITERIA FOR WELD DISCONTINUITIES ARE ADOPTED, UNNECESSARY WELD REPAIRS WILL BE REQUIRED. THIS WILL LEAD TO SIGNIFICANT INCREASES IN FABRICATION COSTS,DELAYS IN PRODUCTION AND TO AN OVERALL REDUCTION IN QUALITY SINCE WELD REPAIRS GENERALLY HAVE AN INFERIOR QUALITY TO ORIGINAL WELDS. UNNECESSARY REPAIRS CAN BE AVOIDED BY ADOPTING A MORE RATIONAL APPROACH TO SETTING ACCEPTANCE CRITERIA FOR WELD DISCONTINUITIES. THESE CRITERIA, FREQUENTLY BASED ON FRACTURE MECHANICS ASSESSMENTS, TAKE INTO CONSIDERATION THE GEOMETRY, THE IMPOSED LOADING DURING SERVICE, POTENTIAL FAILURE MODES AND THE SERVICE ENVIRONMENT. THE PROPOSED PROGRAM ADDRESSES INCOMPLETE JOINT PENETRATION, ONE FORM OF WELD DISCONTINUITY WHICH IS FREQUENTLY ENCOUNTERED DURING FABRICATION. THE RESULTS WILL BE COMPARED WITH THE PERFORMANCE OF COMPLETE PENETRATION JOINTS AND WILL BE USED AS A BASIS FOR SETTING ACCEPTANCE CRITERIA FOR THIS TYPE OF DISCONTINUITY. THE PROPOSED MATERIAL IS 5083-H131 ALUMINUM. THE RESULTS OBTAINED SHOULD BE APPLICABLE TO OTHER MATERIALS. HOWEVER, ALTERNATIVE MATERIALS CAN BE SUBSTITUTED IF THESE ARE CONSIDERED MORE APPROPRIATE.