Cabrini Marina, Lorenzi Sergio, Testa Cristian, Brevi Fabio, Biamino Sara, Fino Paolo, Manfredi Diego, Marchese Giulio, Calignano Flaviana, Pastore Tommaso
Consorzio INSTM, via G. Giusti, 9, 50121 Firenze, Italy.
University of Bergamo, Department of Engineering and Applied Sciences, Viale Marconi 5, 24044 Dalmine, Italy.
Materials (Basel). 2019 May 29;12(11):1742. doi: 10.3390/ma12111742.
The effect of microstructure on the susceptibility to selective corrosion of Alloy 625 produced by laser powder bed fusion (LPBF) process was investigated through intergranular corrosion tests according to ASTM G28 standard. The effect of heat treatment on selective corrosion susceptibility was also evaluated. The behavior was compared to commercial hot-worked, heat treated Grade 1 Alloy 625. The morphology of attack after boiling ferric sulfate-sulfuric acid test according to ASTM G28 standard is less penetrating for LPBF 625 alloy compared to hot-worked and heat-treated alloy both in as-built condition and after heat treatment. The different attack morphology can be ascribed to the oversaturation of the alloying elements in the nickel austenitic matrix obtained due to the very high cooling rate. On as-built specimens, a shallow selective attack of the border of the melt pools was observed, which disappeared after the heat treatment. The results confirmed similar intergranular corrosion susceptibility, but different corrosion morphologies were detected. The results are discussed in relation to the unique microstructures of LPBF manufactured alloys.
通过按照ASTM G28标准进行的晶间腐蚀试验，研究了微观结构对激光粉末床熔融（LPBF）工艺生产的625合金选择性腐蚀敏感性的影响。还评估了热处理对选择性腐蚀敏感性的影响。将该行为与商业热加工、热处理的1级625合金进行了比较。根据ASTM G28标准进行的沸腾硫酸铁-硫酸试验后，LPBF 625合金在原始状态和热处理后的侵蚀形态与热加工和热处理合金相比，穿透性较小。不同的侵蚀形态可归因于由于极高的冷却速率，镍奥氏体基体中合金元素的过饱和。在原始试样上，观察到熔池边缘的浅选择性侵蚀，热处理后这种侵蚀消失。结果证实了类似的晶间腐蚀敏感性，但检测到了不同的腐蚀形态。结合LPBF制造合金独特的微观结构对结果进行了讨论。
