Abstract This work shows in details how the γ→α′(e) (austenite (γ), martensite (α′, e)) strain-induced martensitic transformation affects the cavitation erosion behavior of the solution-treated AISI 304 austenitic stainless steel. For this purpose, mirror-polished surface samples initially presenting ~93 vol% γ + ~7 vol% α′ were subjected to cavitation erosion testing according to ASTM G32-10 , being carefully characterized by X-ray diffraction and hardness measurements at the tested surfaces. Under cavitation, the studied steel surface showed total γ→α′ transformation fraction of ~89 vol% (which supposedly is directly related to the needed ~4 vol% expansion for the transformation), with no effective mass loss for 180 min testing time, clearly defining the transition from the incubation period (IP) to the acceleration stage of the cavitation testing. For this transformation condition, initially presenting remaining ~11 vol% γ fraction, successive material removal steps and XRD analysis were carried out aiming at determining the actual depth at which this cavitation-related transformation takes place into the steel austenitic matrix. In this case, ~57 μm depth was found when XRD patterns before testing (leading to ~93 vol% γ results) were obtained. Finally, the variation of the average γ→α′ transformation rate along all IP presented a maximum level of ~0.60% min−1 between 60-120 min, which is attributed to the great difference on the mechanical properties of the γ and α′ phases, whose volume fractions continuously change at the surface under cavitation, thus affecting the evolution of the referred surface transformation.

中文翻译：

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固溶处理AISI 304奥氏体不锈钢空化中马氏体转变与孵化-加速转变的直接相关性

摘要 这项工作详细展示了γ→α'(e) (奥氏体(γ)、马氏体(α', e)) 应变诱导马氏体转变如何影响固溶处理的AISI 304 奥氏体不锈钢的空蚀行为。为此，根据 ASTM G32-10 对最初呈现 ~93 vol% γ + ~7 vol% α' 的镜面抛光表面样品进行空蚀测试，并在测试时通过 X 射线衍射和硬度测量仔细表征表面。在空化作用下，所研究的钢表面显示总 γ→α' 转变分数为 ~89 vol%（据推测，这与转变所需的 ~4 vol% 膨胀直接相关），在 180 分钟的测试时间内没有有效质量损失，明确定义了从潜伏期 (IP) 到空化测试加速阶段的过渡。对于这种转变条件，最初呈现剩余的~11 vol% γ 分数，进行了连续的材料去除步骤和 XRD 分析，旨在确定这种与空化相关的转变发生到钢奥氏体基体中的实际深度。在这种情况下，当获得测试前的 XRD 图案（导致 ~93 vol% γ 结果）时，发现了 ~57 μm 深度。最后，平均γ→α'转化率在60-120分钟之间的最大水平为~0.60% min-1，这是由于γ和α'的力学性能差异很大相，其体积分数在空化作用下在表面连续变化，