Ambient and high-temperature rotating bending fatigue of as-built and hot isostatic pressed additively manufactured 316L stainless steel
Bibliographic record
Abstract
• HIP removed porosity and raised Σ3 twins in PBF-LB_SS316L from 2.4 % to 33 %. • At 450 °C, HIP improved fatigue endurance (170 MPa vs. 130 MPa as-built). • HIP increased ductility but lowered the fatigue limit to 220 MPa from 240 MPa. • As-built formed many cracks, while HIP formed a single stable crack. • EBSD showed grain coarsening at 450 °C; HIP preserved microstructural stability. This study investigates the effects of Hot Isostatic Pressing (HIP) on the rotating bending fatigue (RBF) performance of Powder Bed Fused-Laser Beam (PBF-LB) 316L stainless steel (SS316L) at both room (25 °C) and elevated temperatures (450 °C). HIP was applied at 1150 °C and 100 MPa for 4 h following stress relief to eliminate porosity and homogenize the microstructure. Advanced microstructural characterization revealed that HIP reduced porosity below detection limits and transformed the melt-pool structure into an equiaxed grain morphology with a significant increase in Σ3 twin boundary fraction (∼2.4 % to 33 %). These changes were accompanied by reduced dislocation density and internal strain. Fatigue testing showed that HIP specimens exhibited superior high-temperature fatigue endurance (170 MPa) compared to as-built samples (130 MPa), due to defect elimination and microstructural stabilization. However, at 25 °C, as-built specimens outperformed HIP ones (240 MPa vs. 220 MPa) owing to retained work-hardened microstructures. Fractographic analysis confirmed these trends: multiple crack initiation sites dominated as-built failures, while HIP fractures showed single-origin cracks with striation growth. Post-fatigue electron backscatter diffraction maps revealed temperature-dependent grain coarsening and dislocation accumulation, particularly in the as-built samples. Overall, HIP significantly enhanced the high-temperature fatigue resistance of PBF-LB_SS316L by improving microstructural integrity and delaying crack initiation, highlighting the importance of post-processing in AM components.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".