Repairability and effectiveness in direct energy deposition of 316L stainless steel grooves: A comparative study on varying laser strategy

Direct energy deposition (DED) has gained attention in the field of metal repair because of its ability to integrate additively deposited material with preexisting components. Having the beneficial aspects of depositing right material, DED is evaluated the best option for repair deposition. Machining grooves in damaged components is the common first to repair, which is necessary to remove cracked or damaged material and provide suitable geometry for deposition. Preprocessing as grooving is commonly applied to prevent the propagation cracks or tears. However, challenges such as dimensional error and crack induced by residual stress emerge owning to complex interactions between the DED parameters and groove geometry during repair deposition. This study investigates effective deposition strategies for repairing 316L stainless steel grooves with wall-angles of 90° and 135° by exploring the relationship between the repair integrity and parameters such as groove angles, laser energy input, and powder supply, all with reference to the underlying mechanism of metallurgical bonding in angled areas. Based thereon, a modified effective repair strategy is proposed, using enhanced dual laser power to address bonding issues in the angled areas. Samples repaired using this method exhibit a defect-free groove–deposit interface and a continuous columnar-grained microstructure with abrupt changes in grain size between the repaired area and groove. This microstructural heterogeneity results in an exceptional combination of strength and ductility when compared to the base material and samples repaired using a single laser strategy. The findings of this study provide insights into the optimization of DED strategies for achieving robust metallurgical bonding within grooves, thereby advancing technological maturity in the field of metal repair. [Display omitted] •Repair depositions into groove with angle of 90° and 135° were conducted by DED process with SS316L materials.•Repair deposition for both groove angles exhibits an unfused area and few defects at the interface.•Modified strategy was proposed to address defects for 135° groove with enhanced laser power at angle area.•Proposed strategy proved its effectiveness via eliminating defects, achieving exceptional tensile properties.