„*T L in$! OF STAND 4 TECF r Reference A 1 1 1 0 b 2bD5bT NBSIR 84-3001 NBS Publi- cations EFFECT OF CRACK-TIP REGION CONSTRAINT ON FRACTURE IN THE DUCTILE-TO-BRITTLE TRANSITION National Bureau of Standards U.S. Department of Commerce Boulder, Colorado 80303 May 1 984