激光温喷丸强化Inconel718镍基合金热腐蚀性能研究

Research on Hot-Corrosion of Inconel718 Nickel-Based Alloy Treated by Warm Laser Shock Peening

利用Spit Light2000型纳秒激光器对Inconel718镍基合金进行激光温喷丸(WLSP)强化实验,将WLSP强化试样置于700℃混合熔盐(75%Na2SO4+25%Na Cl,百分数指质量分数)中进行热腐蚀实验,对腐蚀前后的WLSP强化试样进行质量损失检测、X射线衍射(XRD)分析以及腐蚀形貌观察,探索了WLSP改善Inconel718镍基合金耐热腐蚀性的机理。结果表明,腐蚀10 h与25 h后260℃-WLSP试样的质量损失分别为未处理试样的18.9%与17.9%。WLSP热腐蚀10 h后试样表面的Cr2O3氧化膜未出现明显剥落,且没有Cr S、Ni O产物生成,说明WLSP处理后的试样表面没有受到S的侵蚀,故能有效抑制材料热腐蚀行为的发生,分析认为WLSP试样表面微观组织的晶粒细化及γ″相析出物能有效减缓O、S的侵入,进而有效提高Inconel718镍基合金的耐热腐蚀性能。

A Spit Light2000 nanosecond laser is used to conduct warm laser shock peening（WLSP） experiment on Inconel718 nickel-based alloys. Thermal corrosion test is conducted on the WLSP-samples and untreated samples in mixed molten salt（75%Na）2SO_4＋25% Na Cl, percentage mentioned above denotes mass fraction） at 700 ℃. Then the mechanism of WLSP to improve the corrosion resistance of Inconel718 nickel-based alloys is researched by quality detection, X-ray diffraction（XRD） diffraction analysis and corrosion morphology observation. The results show that quality losses in 260 ℃-WLSP-samples after 10 h and 25 h are 18.9% and 17.9% of that in untreated samples. In addition, after thermal corrosion for 10 h, Cr_2O_3 oxidation doesn′t peel obviously on the corrosion surface of WLSP-samples and thus Cr S or Ni O is not formed. It is indicated that WLSP-samples can prevent implantation of S and thus effectively suppresses thermal corrosion of materials. The reason is that WLSP can lead to grain refinement and γ″-phase precipitates, which effectively prevents invasion of O and S, and thus improves thermal corrosion resistance of Inconel718 nickel-based alloys.