海洋环境下不同低膨胀高温合金腐蚀抗力的比较研究

Comparison and Research on Corrosion Resistance Behavior of Various Low Thermal Expansion Superalloys Under Simulated Marine Environment

研究比较了不同低膨胀高温合金在模拟海洋盐雾环境中的耐腐蚀性能和表面沉积盐对不同低膨胀高温合金高温抗氧化性能和力学性能的影响。试验结果发现:在35℃模拟海洋盐雾环境下,GH907、GH909和GH929C低膨胀高温合金的耐腐蚀性能比较差,在16小时开始锈蚀,到258小时的平均腐蚀速率约为0.01-0.05 g/m2·h。GH783合金在50小时开始出锈,且为点蚀,到500小时的平均腐蚀速率在0.009-0.011 g/m2·h之间。GH242合金到550小时后仍不出锈。盐雾环境在合金表面产生的沉积盐对Fe-Ni-Co基低膨胀高温合金的高温氧化速率有显著的促进作用。在550-700℃,表面沉积盐使GH907和GH909合金高温氧化速率的提高为GH783和GH242合金的2-4倍。表面沉积盐引起合金表面氧化速率的提高使GH907和GH909合金在650℃的拉伸强度和持久寿命显著降低。

Research and comparison were made on corrosion resistance of various low thermal expansion superalloys under simulated marine salt fog environment and the effect of surface deposited salt on oxidation resistance and mechanical properties at elevated temperature. The results were found that GH907,GH909 and GH9292 C displayed very bad corrosion resistance under marine salt fog environment at 35℃, rust had appeared after exposure for 16 hrs, and the average corrosion rate was 0.01-0.05 g/m2·h for exposure of 258 hrs. Rust began appearing on the surface of GH783 alloy after exposure of 50 hrs, some pitting was also found on the exposure surface, and the average corrosion rate was about 0.009-0.011 g/m2·h for exposure of 500 hrs. GH242 alloy displayed excellent corrosion resistance under the salt fog environment, no evidence of rust was found on the surface after exposure of 550 hrs. It is found that the deposited salt produced in the salt fog environment on alloy surface promoted oxidation at elevated temperatures obviously for such Fe-Ni-Co base LTE superalloys. The oxidation rate at elevated temperature was increased 2-4 times by the deposited salt for GH907 and GH909 alloy comparing with GH783 and GH242 alloy, which further reduced tensile strength and stress rupture life of GH907 and GH909 alloy at 650℃ obviously.