激光定向生长修复DZ125L柱状晶叶片力学性能研究

Research on Mechanical Properties of DZ125L Columnar Crystal Blade Directionally Repaired by Laser Direct Forming

在DZ125L定向基材上进行激光直接成形同种材料的定向生长修复，对修复后的DZ125L熔覆组织进行了微观分析和常温力学性能测试，并对熔覆组织与定向基材的结合面强度进行了测试。结果表明：激光直接成形DZ125L的组织为外延生长的柱状晶组织，其一次枝晶间距为8～12μm，二次枝晶退化，热处理后柱状晶尺寸增大为30～90μm，柱状晶基体上析出大量均匀分布的γ′强化相；沉积态柱状晶组织的纵向抗拉强度为1312MPa，延伸率为5．27％，热处理后柱状晶组织的纵向抗拉强度降低为1201MPa，延伸率达到6．69％，均满足国家标准；熔覆层柱状晶组织与定向基材的结合面力学性能良好，定向生长满足使用要求。

Directional repair of the same material by laser direct forming is performed on the columnar crystal substrate of DZ125L. Microstructure and normal mechanical properties of cladding layers are analyzed and tested. Besides, the mechanical properties of the interface between cladding layers and directional substrate are tested. The results show that the microstructure of laser direct forming DZ125L is columnar crystal with the primary dendrite arm spacing of 8-12μm and the deterioration of secondary dendrite arm. The size of columnar crystal after heat treatment rises to 30-90μm and γ′ strengthening phases separate out on the matrixes of columnar crystals in quantity and uniformly; The longitudinal tensile strength of as-deposited columnar crystal is 1312 MPa, while the elongation is 5.27%. After heat treatment, the longitudinal tensile strength and elongation are 1201 MPa and 6.69%, respectively, which both meet the national standards. The interface between cladding layers and directional substrate shows good mechanical property, which can meet the operation requirements.