The corrosion properties of grain-refined titanium (Ti) after adding yttrium (Y) were characterized to determine how the added Y and the resulting refined grains affected the corrosion resistance of commercially pure Ti (CP-Ti). Microstructural changes, such as grain refinement and Y precipitation, altered corrosion potential, open circuit potential (OCP), and corrosion resistance. Based on the mixed potential theory, adding Y to Ti caused anodic movement of the corrosion potential and OCP and the resultant Y precipitates over 1 μm placed under corrosion. Although Y precipitates larger than 1 μm appeared to be detrimental to the Ti–Y alloys’ corrosion resistance, Y segregation at the grain boundaries and the small Y precipitates in the grains increased the oxide layer’s thickness because of the micro-galvanic effect. Therefore, the grain refinement caused by Y segregation could compensate for the deteriorated corrosion performance coming from the presence of the large Y precipitates when the Y content is limited to 0.1 wt%. Therefore, by controlling the Y content as a grain refiner, not only the desired mechanical properties but the comparative corrosion resistance to CP-Ti could be achieved for plate heat exchangers.

表征了添加钇（Y）后晶粒细化钛（Ti）的腐蚀性能，以确定添加的Y和所得的细化晶粒如何影响商业纯钛（CP-Ti）的耐腐蚀性。微观结构的变化，例如晶粒细化和Y析出，改变的腐蚀电位，开路电位（OCP）和耐腐蚀性。根据混合电势理论，在Ti中添加Y会引起腐蚀电势和OCP的阳极运动，并且在腐蚀下超过1 µm的Y析出。尽管大于1 µm的Y析出物似乎对Ti-Y合金的耐蚀性有害，但由于微电流效应，晶界处的Y偏析和晶粒中小的Y析出物增加了氧化层的厚度。因此，当Y含量限制在0.1 wt％时，由Y偏析引起的晶粒细化可以补偿由于大的Y析出物而导致的腐蚀性能下降。因此，通过控制Y含量作为晶粒细化剂，对于板式热交换器而言，不仅可以实现所需的机械性能，而且可以获得对CP-Ti的比较耐蚀性。