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研究了硼元素含量对Ti-1023合金高周疲劳性能的影响.无硼的Ti-1023合金高周疲劳S-N曲线位置最低,添加0.05％的硼元素后,合金的疲劳极限仅增加了2 MPa,但高周疲劳S-N曲线高应力段明显上移.当硼元素含量为0.1％时,Ti-1023合金的疲劳极限提高10％以上,S-N曲线的位置最高,其疲劳性能得到全面提高.进一步添加硼元素后,S-N曲线位置基本不变.无硼的Ti-1023合金疲劳条带较为清晰,添加硼元素后,Ti-1023合金疲劳试样裂纹源全部位于表面,裂纹前沿区域脆断痕迹明显,解理断面趋于平整,疲劳条带越来越模糊.这是由于添加硼元素后,Ti-1023合金内部的临界裂纹尺寸会减小,使其抵抗疲劳裂纹失稳扩展的能力降低,综合考虑,Ti-1023合金中硼元素的添加量不宜超过0.1％.

The effect of boron on the high-cycle fatigue properties of Ti-1023 alloy was studied.The S-N curve of Ti1023 alloy without boron is the lowest.After addition of 0.05％ boron the σ-1 of the alloy increases only 2 MPa,but its high-stress section of S-N curve is shifted upward significantly.When the boron content is 0.1％,the σ-1 of the alloy increases 10％ and its S-N curve is the highest,which means that the high-cycle fatigue properties is well improved.After further addition of boron the alloy's S-N curve stays nearly same.Ti-1023 alloy's fatigue striations are clear.With the boron added and plasticity reduced,brittle fracture occurs in crack front,cleavage plane tends to be rate and fatigue striations are less and less obvious.However,boron can reduce the critical crack size in the alloy,and reduce the ability of the alloy to resist fatigue crack growth,and the best boron content should not exceed 0.1％.