The dominating role of austenite stability and martensite transformation mechanism on the toughness and ductile-to-brittle-transition temperature of a quenched and partitioned steel
The dominating role of austenite stability and martensite transformation mechanism on the toughness and ductile-to-brittle-transition temperature of a quenched and partitioned steel
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DOI：
10.1016/j.msea.2021.141517
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
Kai Yang;Yu Li;Zhenjun Hong;Shaofeng Du;Tengyu Ma;Shilong Liu;X. Jin
中科院分区：
文献类型：
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作者：
Kai Yang;Yu Li;Zhenjun Hong;Shaofeng Du;Tengyu Ma;Shilong Liu;X. Jin
研究了Fe-0.3C-2.7Mn-1.7Si(wt.%)淬火分割(Q&P)钢的奥氏体稳定性和马氏体相变(MT)机制对拉伸和冲击性能的影响。根据M-S的γ温度，定量评价了不同淬火温度(2 0℃、12 0℃和2 40℃)下Q&P钢中亚稳态残余奥氏体相(σM)的稳定性。结果表明，γ-M的稳定性主要与碳含量、晶粒度/形貌以及周围马氏体提供的应力屏蔽作用有关。此外，与γM对拉伸性能一贯的正相变诱导塑性效应(TRIP)相反，MT对动态冲击性能具有双向影响，这取决于MT机制和相关的M Sσ温度。在高温下，QP120和QP240中的应变诱发MT通过TRIP效应缓解了局部应力集中，阻碍了裂纹的萌生和扩展，而在低温下的应力辅助MT导致了低的裂纹萌生、扩展能和沿晶断裂模式，从而导致QP240样品的冲击韧性低于几乎没有奥氏体的QP20样品。此外，Q&P样品的韧脆转变温度与M-S的σ温度几乎呈线性关系。最后，在QP120试样中获得了强度和伸长率积大、DBTt低、韧性高的优良组合，这主要归功于γM薄膜在拉伸和冲击试验中具有良好的稳定性。
The effect of austenite stability and martensite transformation (MT) mechanism on the tensile and impact properties has been investigated for Fe-0.3 C-2.7 Mn-1.7 Si (wt.%) quenched and partitioned (Q&P) steel. The stability of metastable retained austenite (γ M) in the Q&P steel samples, which were subjected to different quenching temperatures (20, 120, and 240° C), was quantitatively evaluated according to the M s σ temperature. Results suggest that the stability of γ M was mainly related to the carbon content, grain size/morphology, and stress shielding effects provided by the surrounding martensite. In addition, in contrast to the consistently positive transformation-induced plasticity effect (TRIP) of γ M on the tensile properties, MT had a two-side effect on the dynamic impact properties, depending on the MT mechanism and the related M s σ temperature. At high temperatures, the strain-induced MT in the QP120 and QP240 samples relieved the local stress concentration and impeded the crack initiation and propagation by the TRIP effect, whereas the stress-assisted MT at low temperatures resulted in a low crack initiation, propagation energy, and intergranular fracture mode, thereby resulting in a lower impact toughness of the QP240 sample than that of the almost austenite-free QP20 sample. Furthermore, the ductile-to-brittle transition temperature (DBTT) of the Q&P samples showed an almost linear relationship with their M s σ temperature. Finally, an excellent combination of large product of strength and elongation, low DBTT, and high toughness was obtained in the QP120 sample, which was mainly attributed to the good stability of the film γ M during the tensile or impact tests.