Effect of Retained Austenite on Impact Toughness of the Multi-Phase Bainitic-Martensitic Steel
Effect of Retained Austenite on Impact Toughness of the Multi-Phase Bainitic-Martensitic Steel
复制标题
残余奥氏体对多相贝氏体-马氏体钢冲击韧性的影响
DOI：
10.4028/www.scientific.net/amr.922.298
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
D. Santos
中科院分区：
文献类型：
--
作者：
José A. da Cruz;J. J. Vilela;B. M. Gonzalez;D. Santos
新型贝氏体钢在室温下的韧性比传统的淬火和回火马氏体钢更高。这是因为高硅钢（≤ 1.5wt%）的贝氏体相变组织是由细小的贝氏体铁素体片和残余奥氏体分隔而成的。抑制了铁素体的析出，提高了韧性。磷灰石的存在促进了裂纹的成核。此外，残留奥氏体的块状物是不期望的。这种形态是相当不稳定的，并且在小应力的影响下倾向于转变成硬而脆的未回火马氏体，导致低韧性。然而，在这项工作中观察到，残余奥氏体的体积分数越大，多相钢的韧性（10-24 J）越大。韧性的值是独立的是否存在膜或块形式的残余奥氏体。贝氏体相变后回火试样的韧性值（10-14 J）下降。这是因为残余奥氏体块分解成碳化物、马氏体和/或贝氏体。
The new class of bainitic steels can present toughness at room temperature greater than traditional quenched and tempered martensitic steel. This is because the microstructure of steel with high Si content (≈1.5wt%) submitted to bainitic transformation is compose of fine plates of bainitic ferrite separated by retained austenite. The inhibition of cementite precipitation leads to the improvement of toughness. The presence of cementite facilitates the nucleation of cracks. Moreover, the blocks of retained austenite are undesirable. This morphology is rather unstable and tends to transform into hard and brittle untempered martensite under the influence of small stress, contributing to a low toughness. However, it was observed in this work that the greater the volume fraction of retained austenite, the greater is the toughness (10-24 J) for multi-phase steel. The values of toughness were independent whether the retained austenite is present on film or block forms. The decrease of toughness values was observed by the tempered samples after the bainitic transformation (10-14 J). This occurred because the blocks of retained austenite decomposed into carbides, martensite and/or bainite.