Microstructure, mechanical properties and corrosion behavior of NbC modified AISI 440C stainless steel by vacuum sintering and heat treatments
Microstructure, mechanical properties and corrosion behavior of NbC modified AISI 440C stainless steel by vacuum sintering and heat treatments
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DOI：
10.1016/j.jallcom.2017.04.125
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发表时间：
2017-07
影响因子：
6.2
通讯作者：
K. Huang;Shih-Hsien Chang;Pei-Chung Hsieh
中科院分区：
文献类型：
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作者：
K. Huang;Shih-Hsien Chang;Pei-Chung Hsieh
将不同量的碳化铌 (NbC) 粉末（5、10 和 15 wt%）混合并添加到 440C 不锈钢粉末中。复合粉末分别在 1260、1270、1280 和 1290°C 下烧结 1 小时。实验结果表明，440C-NbC复合材料的最佳烧结温度为1270℃。同时，添加5%NbC的440C试件具有最佳横向断裂强度（TRS）值为1985.2MPa，以及最高极化电阻1.01×102Ωcm2。而含有或含有 15 wt% NbC 的 440C 样品在 1280 °C 烧结后显示出 HRA 80.9 的最高硬度值。此外，显微组织评价表明，添加NbC颗粒后，位于晶界的棒状M7C3碳化物逐渐减少，球状M7C3碳化物析出并分散在基体中。热处理后，初级 M7C3 碳化物转化为 M23C6 碳化物，从而导致二次硬化。结果清楚地表明，热处理有效地改善了碳化物的粒径并强化了440C-NbC复合材料的基体。
Different amounts of niobium carbide (NbC) powder (5, 10 and 15 wt%) are mixed and added to 440C stainless steel powder. The composite powders are sintered at 1260, 1270, 1280 and 1290 °C for 1 h, respectively. The experimental results show that the optimal sintering temperature for the 440C-NbC composites is 1270 °C. Meanwhile, the 440C specimens with 5% NbC addition possess the optimal transverse rupture strength (TRS) value of 1985.2 MPa, as well as the highest polarization resistance of 1.01 × 102Ω cm2. While the 440C specimens contain or with 15 wt% NbC show the highest hardness value of HRA 80.9 after sintering at 1280 °C. Furthermore, the microstructural evaluation reveals that the rod-shaped M7C3carbides located on the grain boundaries are gradually reduced after NbC particles are added, and the spherical-shaped M7C3carbides are precipitated and dispersed in the matrix. After heat treatment, the primary M7C3carbides are converted to M23C6carbides, which results in a secondary hardening. The results clearly show that heat treatment effectively improves the particle size of the carbides and strengthens the matrix of the 440C-NbC composites.