CRACK PROPAGATION TESTS OF HIGH-STRENGTH SHEET MATERIALS PART Ⅴ – AIR – MELTED AND CONSUTRODE AMS 6434 STEEL

摘要

Crack propagation tests were conducted on air-melted and consumable-electrode vacuum-remelted SAE Aero¬nautical Materials Specification 6434 (modified AISI 4335 with vanadium), using specimens 1/2 in. or 1-1/2 in. wide and up to 0.125 in. thick, and heat-treated to have yield strength in the range 180 to 210 ksi. The full shear temper-atures obtained with the different thicknesses and heat treat¬ments were lower than those of any other steels of compar¬able thicknesses and yield strengths that have been tested to date, and the net fracture stress values were similarly superior. The consutrode material was significantly better than the air-melted material. Limited data indicated that the transverse properties were not significantly inferior to the longitudinal properties. The FST was higher the thicker the material, as previously observed for other materials. Austenitizing at 1620°F gave better results than at 1575°F, and tempering at 400°F gave better results than at 725°F