Change in fracture mode and selective dissolution of austenitic stainless steels

Tarnishing film-induced brittle cracking of brass

“…Figure 4 shows that a crack originating from the film propagated into the substrate in a brittle manner when it was loaded in air. The result is different from the conclusions of Newman et al 3 and Devasenapathi et al 6 They found that a ductile fracture was obtained in the samples with a dealloyed layer when loaded in air, and a brittle fracture occurred during loading in the solution. Both of the films that they studied were a single-layer film or dealloyed layer.…”

“…Chen et al 5 showed that a Cu-30Au alloy with a dealloyed layer fractured in an intergranular mode under an impact load in 0.6 M NaCl. Devasenapathi et al 6 reported that an Mnsubstituted stainless steel with a layer of thick film showed brittle intergranular SCC under impact load in 1 M HCl, whereas the samples with removed films and subsequently impact loaded in air exhibited ductile fracture. Saito et al 7 showed that film-induced intergranular fracture occurred in Ag-20Au foil after dealloying for 10 s at 1050 mV SCE in 1 M HClO 4 , whereas a ductile fracture occurred after a pore-coarsening treatment to the dealloyed layer under various potentials.…”

“…[1][2][3][4][5][6][7][8] The film-induced cleavage model that has been developed mainly by Sieradzki, Newman, and colleagues [1][2][3][4]7 proposes to explain both transgranular and intergranular SCC resulting from the surface films. The model was based on the idea that a crack, originating in a surface layer, can obtain a high enough velocity to penetrate into the underlying substrate even if the substrate is a facecentered cubic (fcc) metal.…”

A comparative study of stress-corrosion cracking behaviour of three manganese-containing stainless steels in boiling MgCl2 solution

“…Thus, the formation of porous film can be attributed not only to the active dissolution of Mn, but also to the accelerating effect of Cu by a noble metal displacement mechanism. Indeed, the present authors [7] have reported elsewhere the enrichment of Cu in the corrosion film.…”

“…Though no systematic work has been found in the literature on the effect of Mn on the passive film stability, in general the passivation tendency is reported [6] to deteriorate in aggressive environments. Studies carried out on Mn stainless steels [7] show that the films formed on these alloys are highly porous and less protective. Furthermore, the U-bends tested in boiling MgC12 solutions in the present study exhibited thick porous films which in turn minimize the SCC susceptibility.…”