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Morphology and mechanisms of cavitation damage on lamellar gray iron surfaces
Wear ( IF 5.3 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.wear.2020.203324
Marcio Abreu , Jill Sundberg , Jessica Elfsberg , Stefan Jonsson

Abstract Engine parts in contact with liquids may suffer cavitation erosion damage. Understanding its mechanisms in realistic operating environments is necessary for improvements in the service life and durability of materials for heavy-duty diesel engines. This work illustrates the cavitation erosion behavior of a cylinder liner material with a follow-up of detailed, high-magnification SEM images of damaged sites on the surface. The cylinder liner encloses the piston and combustion chamber in the engine of large trucks and its material of choice is usually a lamellar gray cast iron, its microstructure consisting of flake-shaped graphite, a pearlitic matrix and some steadite. Testing was carried out using an ultrasonic vibratory apparatus, and the liquid of choice was a commercial engine coolant composed of water, glycol and inhibitors. Based on observations of tested surfaces, a sequence of damage patterns is proposed as an explanation of the material’s cavitation erosion behavior. Initiation consists of: chipping at graphite cluster centers, graphite flake removal, pitting along graphite flakes and direct matrix pitting. Development consists of: evolution of chipped spots into matrix-damaging pits, radial pit expansion, pit merging and surface roughening. It can be concluded that presence and morphology of graphite are critical to the cavitation erosion behavior of LGI.

中文翻译:

层状灰口铸铁表面空化损伤的形态和机制

摘要 与液体接触的发动机部件可能会遭受气蚀损坏。了解其在现实操作环境中的机制对于提高重型柴油发动机材料的使用寿命和耐用性是必要的。这项工作说明了汽缸套材料的气穴侵蚀行为,并附有表面损坏部位的详细、高倍放大 SEM 图像。汽缸套包围着大型卡车发动机的活塞和燃烧室,其材料通常为片状灰口铸铁,其微观结构由片状石墨、珠光体基体和一些斯氏体组成。使用超声波振动装置进行测试,选择的液体是由水、乙二醇和抑制剂组成的商用发动机冷却液。基于对测试表面的观察,提出了一系列损坏模式,以解释材料的空化侵蚀行为。引发包括:在石墨簇中心切屑、去除石墨片、沿石墨片形成点蚀和直接基体点蚀。发展包括:缺口演变成破坏基质的坑、径向坑扩展、坑合并和表面粗糙化。可以得出结论,石墨的存在和形态对 LGI 的空蚀行为至关重要。缺口演变成破坏基质的凹坑、径向凹坑扩展、凹坑合并和表面粗糙化。可以得出结论,石墨的存在和形态对 LGI 的空蚀行为至关重要。缺口演变成破坏基质的凹坑、径向凹坑扩展、凹坑合并和表面粗糙化。可以得出结论,石墨的存在和形态对 LGI 的空蚀行为至关重要。
更新日期:2020-09-01
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