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针对TC4钛合金CO2激光深熔焊接接头具有组织性能非线性大梯度特征,并对其塑性损伤行为产生影响的科学问题,采用多试样拉伸试验法研究其非线性塑性损伤行为,提出采用金相法检测的微孔洞体积分数以表征塑性损伤程度。结果表明:TC4钛合金激光深熔焊接头的塑性损伤过程表现为微孔洞的产生与聚合;微孔洞体积分数沿焊接接头从焊缝、热影响区(HAZ)至母材呈非线性分布;激光焊接接头的焊缝、HAZ和母材的微孔洞长大规律和施加应力与显微组织有关,在应力较小时,粗大的晶粒尺寸使得焊缝损伤大于HAZ损伤,而在应力较大时,晶内微孔洞使得HAZ损伤大于焊缝;而且随着施加应力的增大,HAZ中的微孔洞体积分数增长速度比焊缝快。
Aiming at the scientific problem that TC4 titanium alloy CO2 laser deep fusion welded joint possesses non-linear large gradient characteristic of microstructure and affects its plastic damage behavior, the multi-specimen tensile test is used to study the nonlinear plasticity damage behavior. The metallographic method The volume fraction of micropores detected to characterize the extent of plastic damage. The results show that the plastic damage process of TC4 titanium alloy laser deep-welded joints is the formation and polymerization of micro-holes. The volume fraction of micro-holes along the welded joints is nonlinearly distributed from the weld and HAZ to the base metal ; Welds in laser welding joints, HAZ and base metal micropores grow up regularly and exert stress on the microstructure. When the stress is small, the coarse grain size makes the weld damage greater than the HAZ damage, Large, intracrystalline micro-cavities make the HAZ damage greater than the weld; and with the increase of applied stress, the volume fraction of micro-cavities in the HAZ increases faster than the weld.