Influence of P, As and Sb on the susceptibility to SCC of alpha-beta ' brasses

The influence of P, As and Sb on the susceptibility to SCC of alpha-beta' b rasses in different non ammoniated solutions was studied. Two series of bra sses were tested: the first one with only 5 - 10% of beta' phase and the se cond one with 54-56% of beta' phase. The VB group elements were present at two different concentrations. Susceptibility to SCC was evaluated by SSRT, at a strain rate of 1 x 10(-6) s(-1), in concentrated (1M) or diluted (50 and 200 ppm) solutions of Na2SO 4, NaNO2, NaCl, at room temperature. The brasses of second series were foun d to be more susceptible to SCC than those of the first series in all the e nvironments studied. Sb drastically increased SCC susceptibility of the bra sses of the first series, while As showed a beneficial effect. The three VB group elements produced a limited inhibiting effect on susceptibility to S CC in the second series of brasses. Susceptibility to SCC of all the brasses was compared with the tendency to dezincification, measured by means of the 6509 ISO Standard Test. The influ ence of the VB group elements on the two types of corrosion was not compara ble.