The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the ...The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the effects of dry/wet ratio(DWR) and pre-immersion on SCC.Fracture and side surface characterizations were observed by scanning electron microscopy(SEM).The results demonstrate that SCC susceptibility decreases with an increase of the DWR. With an increase of the pre-immersion time, both continuous pre-immersion(CP) and wet-dry cyclic preimmersion(WDP) samples are more sensitive to SCC, and the cracking mode in the SCC fracture region is intergranular. Furthermore, the effect of WDP on SCC is greater than that of CP when the total time immersed in solution before an SSRT is the same with each other. In fact, each single wetdry cycle can be divided into three processes with respect to the change of solution on samples’ surface. Volatilization of water on the surface results in an increase in solute concentration, thus accelerating corrosion.展开更多
Weathering steel is widely used in various fields due to its excellent mechanical properties and high corrosion resistance. The effect of chromium content on the S450 EW weathering steel in cyclic immersion test was s...Weathering steel is widely used in various fields due to its excellent mechanical properties and high corrosion resistance. The effect of chromium content on the S450 EW weathering steel in cyclic immersion test was studied. The results indicated that the corrosion resistance of S450 EW weathering steel is closely related to chromium content. The addition of chromium significantly inhibited the weathering steel corrosion. The corrosion rate of experimental steel after 96 h immersion was 1.101 g·m-2·h-1. The rust of S450 EW weathering steel was mainly constituted of Fe OOH and Fe3O4 phase, and the elevation of chromium content promoted the formation of α-Fe OOH. The fine precipitates of the two phases contributed to the formation of dense dust layer of test steel. Furthermore, the increase of chromium is beneficial for the cure of original defects and cracks of the rust layer via the enrichment of chromium. The corrosion potential and the resistance of corrosion process were thus increased, protecting the experimental steel from further corrosion. A S450 EW steel with corrosion resistance more than 1.5 times of Q450NQR1 steel was prepared.展开更多
基金co-supported by the National Natural Science Foundation of China (No. 51671013)the Beijing Nova Program of China (No. Z161100004916061)
文摘The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the effects of dry/wet ratio(DWR) and pre-immersion on SCC.Fracture and side surface characterizations were observed by scanning electron microscopy(SEM).The results demonstrate that SCC susceptibility decreases with an increase of the DWR. With an increase of the pre-immersion time, both continuous pre-immersion(CP) and wet-dry cyclic preimmersion(WDP) samples are more sensitive to SCC, and the cracking mode in the SCC fracture region is intergranular. Furthermore, the effect of WDP on SCC is greater than that of CP when the total time immersed in solution before an SSRT is the same with each other. In fact, each single wetdry cycle can be divided into three processes with respect to the change of solution on samples’ surface. Volatilization of water on the surface results in an increase in solute concentration, thus accelerating corrosion.
基金Item Sponsored by National Natural Science Foundation of China(51104039)Fundamental Research Funds for the National Key Basic Research Program of China(2012CB626812)
文摘Weathering steel is widely used in various fields due to its excellent mechanical properties and high corrosion resistance. The effect of chromium content on the S450 EW weathering steel in cyclic immersion test was studied. The results indicated that the corrosion resistance of S450 EW weathering steel is closely related to chromium content. The addition of chromium significantly inhibited the weathering steel corrosion. The corrosion rate of experimental steel after 96 h immersion was 1.101 g·m-2·h-1. The rust of S450 EW weathering steel was mainly constituted of Fe OOH and Fe3O4 phase, and the elevation of chromium content promoted the formation of α-Fe OOH. The fine precipitates of the two phases contributed to the formation of dense dust layer of test steel. Furthermore, the increase of chromium is beneficial for the cure of original defects and cracks of the rust layer via the enrichment of chromium. The corrosion potential and the resistance of corrosion process were thus increased, protecting the experimental steel from further corrosion. A S450 EW steel with corrosion resistance more than 1.5 times of Q450NQR1 steel was prepared.
