In-process optical monitoring of contamination in an additively manufactured titanium alloy
In-process optical monitoring of contamination in an additively manufactured titanium alloy
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DOI：
10.1117/12.2666339
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发表时间：
2023-05
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影响因子：
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通讯作者：
Nina Binaei;J. Hodgkinson;K. Mullaney;E. Chehura;Stewart Williams;R. Tatam
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作者：
Nina Binaei;J. Hodgkinson;K. Mullaney;E. Chehura;Stewart Williams;R. Tatam
在线光学监测已经在通过线和电弧增材制造（WAAM）制造的金属零件的质量控制方面取得了令人印象深刻的增强。在WAAM工艺期间识别材料缺陷提供了减少工艺后检查、暂停沉积以解决缺陷问题或终止工艺以节省资源的机会。这在航空航天领域非常重要，因为劣质部件可能会带来重大的成本损失。许多工艺因素，包括沉积参数、WAAM设备、原料、周围大气和污染物，都可能导致部件中产生缺陷。污染物可以作为来自沉积气氛、WAAM系统本身或原料的有机物（油/油脂）或无机元素引入。钨的污染（源自等离子体炬电极）是一个特别值得关注的问题，因为其熔点为3422 ° C，远高于钛合金（Ti-6Al-4V为1674 ° C）[1]。在WAAM熔池内，钨的凝固液滴可能保持溶解状态，这可能导致拉伸载荷下最终部件的缺陷。在这里，我们展示了一个光学发射光谱系统的发展，以确定钨作为污染物。在该过程期间使用具有110 ms的积分时间的光谱仪从等离子体获得光谱。进行数据分析以在较长的时间尺度上求平均值，并明确识别污染钨的发射线。
In-process optical monitoring has led to impressive enhancements in the quality control of metallic parts made by wire and arc additive manufacturing (WAAM). Identification of material defects during a WAAM process gives an opportunity to reduce post-process inspection, to pause the deposition to address the defect problem or terminate the process to save resources. This is of importance in the aerospace sector, where inferior quality components can have significant cost penalties. Many process factors, including deposition parameters, WAAM equipment, feedstock, the surrounding atmosphere and contaminants can all contribute to create a defect in the component. The contaminants can be introduced as organics (oils / grease) or inorganic elements coming from the deposition atmosphere, the WAAM system itself or the feedstock material. Contamination by tungsten (originating in the plasma torch electrode) is a particular concern as its melting point, 3422C, is much higher than that of titanium alloy (1674C for Ti-6Al-4V)[1]. Within the WAAM melt pool, a solidified drop of tungsten can remain dissolved which could result in a defect in the final part under tensile loading. Here, we demonstrate the development of an optical emission spectroscopy system to identify tungsten as a contaminant. Spectra were obtained from the plasma during the process using a spectrometer with an integration time of 110ms. Data analysis was undertaken to average over longer timescales, and unambiguously identify the emission lines of contaminating tungsten.