Orientation dependence of stress corrosion crack in cold rolled alpha brass

Abstract

IINVESTIGATIONS on susceptibility of 70-30 brass or cartridge brass to stress corrosion failure commonly known as season cracking was studied even before 1914.1 Up to date the phenomenon has been investigated in its various aspects, namely (a) determination of the stress corrosion behaviour of 70 30 brass in various media, under different conditions of temperature, stress and strain,1,2,3,4,5,6(b) under various metallurgical cond-itions such as work hardening, heat treatment, grain coarsening and refining and alloying.5,7 The results so far indicate that (i) ammonium atmosphere in presence of moisture is the most harmful environment,(ii) suscep-tibility decreases with increase in cold work beyond a minimum amount as well as with grain refinement for uniaxially loaded specimens, and (iii) small addition of individual elements such as Si, Ba, fvlg, As, l increases the resistance to stress corrosion failure. Various hypotheses have been proposed to explain the phenomenon of stress corrosion failure of alloys. Some of them have been confirmed experimentally. A large number of invest-igators have studied the phenomenon in diverse alloys at different periods starting from as early as 1918. The knowledge is not yet complete to formulate a general theory to explain the phenomenology of stress corrosion failure of alloys.There is a general agreement that pure metals are not susceptible to stress corrosion failure," and the failure is due to the combined effects of corrosion and stress . The confusion and disagreement lie in the share of responsibilities of the two agents, corrosion and stress, in the initiation and propagation of the crack resulting in fracture.