Advanced alloy surface modification using ultrasonic pulsed waterjets

金属合金的表面改性是提高合金疲劳、耐磨性、耐蚀性等性能的重要方法。传统上，这可以通过喷丸或喷砂来实现，而激光冲击喷丸技术现在也可用。最近，VLN先进技术公司（渥太华，ON）开发了一种新的超声脉冲水射流制造技术。这种方法允许精密金属切割和控制表面涂层的去除（例如，镀硬铬）。然而，也证明了表面喷丸是可能的，与传统的喷丸技术相比，水射流技术更环保，物理上更清洁。与VLN和GKN Sinter Metals （St. Thomas， ON）合作进行的拟议研究将研究超声波水射流强化过程中的基本物理机制，特别是潜在的空化现象以及相关材料的相互作用。将研究水射流强化对各种铝、铁和钛合金的影响，这些合金采用粉末冶金或增材制造制造，并与传统的变形合金进行比较。这些材料对加拿大的航空航天和汽车工业非常重要。通过x射线衍射量化强化后产生的残余表面应力的程度和深度，并研究其对各种物理和化学性能的影响。表面表征将使用几种轮廓术和显微镜技术进行。预喷和后喷的疲劳响应将被评估。喷丸材料的磨损和腐蚀响应将被研究，因为这两者都对冶金表面状况很敏感，而冶金表面状况将受到喷丸处理的强烈影响。再结晶反应也将被评估，使用差示扫描量热法和电子背散射衍射。这个多学科项目的成功完成将为该技术提供科学和工程验证，并为VLN和GKN提供国际竞争优势。

Surface modification of metallic alloys is an important method for improving properties such as fatigue, wear resistance, and even the corrosion susceptibility. Traditionally, this can be achieved by shot peening or grit blasting, while laser shock peening techniques are also now available. Recently, a novel ultrasonic pulsed waterjet manufacturing technique has been developed by VLN Advanced Technologies (Ottawa, ON). This method allows precision metal cutting and controlled removal of surface coatings (e.g., hard chromium plating). However, it has also been demonstrated that surface peening may be possible, with the waterjet technique being much more environmentally friendly, and physically cleaner, than conventional shot peening. The proposed research, in collaboration with both VLN and GKN Sinter Metals (St. Thomas, ON), will investigate the fundamental physical mechanisms operating during ultrasonic waterjet peening, particularly in terms of potential cavitation phenomena, and the associated materials interactions. The effects of waterjet peening will be investigated for various aluminium, iron and titanium alloys, fabricated using either powder metallurgy or additive manufacturing, and compared to conventional wrought alloy variants. These materials are of great importance to the aerospace and automotive industries within Canada. The degree and depth of residual surface stress generated following peening will be quantified through X-ray diffraction, and the effects on a variety of physical and chemical properties will be investigated. Surface characterisation will be conducted using several profilometry and microscopy techniques. The pre- and post-peened fatigue response will be assessed. The wear and corrosion response of the peened materials will be investigated, as both are sensitive to the metallurgical surface condition, which will be strongly affected through peening treatments. The recrystallization response will also be assessed, using differential scanning calorimetry and electron back scatter diffraction. Successful completion of this multi-disciplinary project will provide a scientific and engineering validation of the technique, and an international competitive advantage for both VLN and GKN.