Experimental and numerical study on plasma nitriding of AISI P20 mold steel
Experimental and numerical study on plasma nitriding of AISI P20 mold steel
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DOI：
10.1007/s12613-016-1324-y
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
N. Nayebpashaee;H. Vafaeenezhad;S. Kheirandish;M. Soltanieh
中科院分区：
文献类型：
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作者：
N. Nayebpashaee;H. Vafaeenezhad;S. Kheirandish;M. Soltanieh
在本研究中，在三种工艺温度(450°C、500°C和550°C)和一定的时间范围(2.5、5、7.5和10h)下，在固定的氮气：氢气比例为75vol%：25vol%的条件下，采用离子渗氮技术在AISI P20钢表面制备了一层硬质保护层。用光学显微镜和扫描电子显微镜对样品的形貌进行了研究，并用X射线衍射仪确定了每个样品的形成相。用能量色散X射线光谱仪、波长色散光谱仪和辉光色散光谱仪测量了元素的深度分布。确定了样品的硬度分布，并记录了从表面到样品中心的显微硬度分布。结果表明，在所有的渗氮策略中，ε-氮化物是渗氮的主要成分，离子渗氮可使硬度提高3倍以上。结果表明，随着时间的延长和温度的升高，扩散层的硬度和硬度深度显著增加。此外，还利用人工神经网络预测了操作参数对塑料模具钢力学性能的影响。网络输入为等离子体温度、施加时间和靶距，模型的输出为维氏硬度测量。该模型准确地再现了不同操作条件下的实验结果，可用于AISI P20钢离子渗氮过程的有效模拟。
In this study, plasma nitriding was used to fabricate a hard protective layer on AISI P20 steel, at three process temperatures (450°C, 500°C, and 550°C) and over a range of time periods (2.5, 5, 7.5, and 10 h), and at a fixed gas N2:H2ratio of 75vol%:25vol%. The morphology of samples was studied using optical microscopy and scanning electron microscopy, and the formed phase of each sample was determined by X-ray diffraction. The elemental depth profile was measured by energy dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and glow dispersive spectroscopy. The hardness profile of the samples was identified, and the microhardness profile from the surface to the sample center was recorded. The results show that ε-nitride is the dominant species after carrying out plasma nitriding in all strategies and that the plasma nitriding process improves the hardness up to more than three times. It is found that as the time and temperature of the process increase, the hardness and hardness depth of the diffusion zone considerably increase. Furthermore, artificial neural networks were used to predict the effects of operational parameters on the mechanical properties of plastic mold steel. The plasma temperature, running time of imposition, and target distance to the sample surface were all used as network inputs; Vickers hardness measurements were given as the output of the model. The model accurately reproduced the experimental outcomes under different operational conditions; therefore, it can be used in the effective simulation of the plasma nitriding process in AISI P20 steel.