Effect of Heat Treatment on Mechanical Properties and Fatigue Behaviors of a Selective Laser Melting Nickel-Based Superalloy
Source abstract
Abstract
This investigation elucidates the elevated-temperature (650 °C) monotonic mechanical response and very-high-cycle fatigue (VHCF) characteristics of Inconel 718 superalloys additively manufactured via selective laser melting (SLM), with a comparative assessment between the as-built and post-process heat-treated states. The results indicate that mechanical performance improves after heat treatment, primarily due to the formation of γ′ and γ″ precipitates, which interact with dislocations to strengthen the alloy. Relative to the as-built specimens, the fatigue strength of the specimen after heat treatment has increased by more than twice. For the as-built specimen, fatigue cracks nucleate at the specimen surface. However, in the high stress range, crack initiation in the heat-treated specimens consistently occurs at the free surface, whereas under low stress conditions, the crack initiation site transitions to the subsurface region encompassing internal defects. Post heat treatment, the fatigue crack trajectory adopts a markedly ductile and tortuous morphology, engendered by the concerted influence of grain-boundary (Laves/δ) precipitates that enforce repeated crack deflection, matrix-strengthening phases that homogenize plastic strain and the attendant reduction in local strain accumulation under the effect of cyclic load.
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Research context
OpenAlex topics: Additive Manufacturing Materials and Processes · Cellular and Composite Structures · High Temperature Alloys and Creep
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
School of Aeronautics and Astronautics, Tianjin Sino-German University of Applied Sciences, Tianjin 300350, China
Tianjin Key Laboratory of High Performance Precision Forming Manufacturing Technology and Equipment, School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin 300222, China
Wheel Rail Center, Tianjin Research Institute for Advanced Equipment, Tsinghua University, Tianjin 300300, China
School of Control and Mechanical Engineering, Tianjin Chengjian University, Tianjin 300384, China
School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
Funding
Tianjin Natural Science Foundation
References (43)
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