Ko Kwang Kyu, Jang Jin Ho, Tiwari Saurabh, Bae Hyo Ju, Sung Hyo Kyung, Kim Jung Gi, Seol Jae Bok
Department of Materials Engineering and Convergence Technology, Gyeongsang National University (GNU), Jinju, 52828, Republic of Korea.
Department of Materials Engineering and Convergence Technology, Center for K-metal, Gyeongsang National University (GNU), Jinju, 52828, South Korea.
Appl Microsc. 2022 Jun 18;52(1):5. doi: 10.1186/s42649-022-00074-1.
The use of Pipelines for long-distance transportation of crude oil, natural gas and similar applications is increasing and has pivotal importance in recent times. High specific strength plays a crucial role in improving transport efficiency through increased pressure and improved laying efficiency through reduced diameter and weight of line pipes. TRIP-based high-strength and high-ductility alloys comprise a mixture of ferrite, bainite, and retained austenite that provide excellent mechanical properties such as dimensional stability, fatigue strength, and impact toughness. This study performs microstructure analysis using both Nital etching and LePera etching methods. At the time of Nital etching, it is difficult to distinctly observe second phase. However, using LePera etching conditions it is possible to distinctly measure the M/A phase and ferrite matrix. The fraction measurement was done using OM and SEM images which give similar results for the average volume fraction of the phases. Although it is possible to distinguish the M/A phase from the SEM image of the sample subjected to LePera etching. However, using Nital etching is nearly impossible. Nital etching is good at specific phase analysis than LePera etching when using SEM images.
管道用于原油、天然气的长途运输及类似应用的情况日益增多，且在当下具有至关重要的意义。高比强度对于通过提高压力来提升运输效率以及通过减小管道直径和重量来提高铺设效率起着关键作用。基于相变诱发塑性的高强度高延展性合金由铁素体、贝氏体和残余奥氏体混合而成，具备诸如尺寸稳定性、疲劳强度和冲击韧性等优异的机械性能。本研究采用硝酸酒精腐蚀和莱佩拉腐蚀两种方法进行微观结构分析。在硝酸酒精腐蚀时，难以清晰观察到第二相。然而，采用莱佩拉腐蚀条件时，能够清晰测量M/A相和铁素体基体。相分数测量是使用金相显微镜（OM）和扫描电子显微镜（SEM）图像完成的，二者给出的相平均体积分数结果相似。尽管从经莱佩拉腐蚀的样品的扫描电子显微镜图像中能够区分出M/A相。然而，使用硝酸酒精腐蚀几乎无法做到。当使用扫描电子显微镜图像时，硝酸酒精腐蚀在特定相分析方面比莱佩拉腐蚀更具优势。
