To research the crack growth characteristics of diffusion bonded laminates with localized no-welded region of TC4 titanium alloy, the fatigue tests for 8mm thick TC4 three-layer diffusion bonded laminates with localized φ15mm and φ15mm no-welded area were conducted under the constant amplitude fatigue stress of R =0.093 inserted with marker load of R =0.7. The crack growth (a, N) data were obtained by QF. The analysis on the failure surface shows the crack growth could be divided into three phases. The contrast on the da/dN-α curves of those coupons shows that the crack growth characteristic in the no-welded area has no difference, the crack growth rate of the φ15mm no-welded area is lower than that of φ12mm no-welded area in the welded boundary area.%带有局部圆形止焊区的钛合金扩散连接层合板能够改善层合板在拉-拉疲劳载荷作用下的裂纹扩展性能,为了研究止焊区尺寸对裂纹扩展寿命的影响,采用3mm,2mm,3mm厚钛合金板材通过扩散连接成8mm厚层合板,层合前预留Φ12mm,Φ15mm止焊区,并加工成含中心Φ6mm孔的板状试件,进行了两类试件在含标识载荷的等幅载荷下的疲劳试验.通过断口判读裂纹形态和尺寸,得到裂纹扩展(a,N)数据,建立了裂纹扩展da/dN-a曲线,对裂纹扩展行为进行了对比.结果表明,裂纹扩展可分为3个阶段；止焊区尺寸对止焊区内裂纹扩展行为无明显影响,但随着止焊区尺寸的增加,止焊区边界附近和越过边界后的裂纹扩展速率有减缓趋势.
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