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在 17-4PH不锈钢上热浸镀铝,然后进行扩散退火处理。研究了热浸镀铝层的显微组织和显微硬度的变化,并考察了其高温耐氧化性能。结果表明:17-4PH 不锈钢热浸镀铝后表面分为富铝层、合金层、基体层等3层,合金层主要相为Fe2Al5。经 950 °C、1 h的扩散处理后,富铝层全部转变为合金层,厚度约为100 μm,且分为内扩散层与外扩散层。内扩散层厚度约为40 μm,主要相为 Fe3Al;外扩散层主要相为FeAl。合金层的显微硬度从表面到基体逐渐降低,表面显微硬度最高达到714 HV。17-4PH 不锈钢经热浸镀铝后,其高温耐氧化性能显著提高。在1000 °C,热浸镀铝件的高温耐氧化性能约是未镀铝件的 7 倍。在氧化过程中,表层致密的γ-Al2O3氧化膜和金属间化合物FeAl、Fe3Al起到高温耐氧化的作用。
Hot-dip aluminized on 17-4PH stainless steel and then diffusion-annealed. The microstructure and microhardness of the hot-dipped aluminum layer were investigated. The high-temperature oxidation resistance was also investigated. The results show that the surface of 17-4PH stainless steel after hot-dip aluminizing is divided into three layers of aluminum-rich layer, alloy layer and matrix layer. The main phase of alloy layer is Fe2Al5. After 950 ° C, 1 h diffusion treatment, the Al-rich layer was all transformed into an alloy layer with a thickness of about 100 μm and was divided into an inner diffusion layer and an outer diffusion layer. The thickness of the inner diffusion layer is about 40 μm, the main phase is Fe3Al, and the main phase of the outer diffusion layer is FeAl. The microhardness of the alloy layer gradually decreases from the surface to the substrate, and the surface microhardness reaches up to 714 HV. 17-4PH stainless steel by hot dip aluminum, the high temperature oxidation resistance was significantly improved. At 1000 ° C, hot-dip aluminized pieces of high temperature oxidation resistance is about 7 times that of un-plated pieces. In the oxidation process, the surface dense γ-Al2O3 oxide film and intermetallic compounds FeAl, Fe3Al play a role of high temperature oxidation resistance.