This study investigated the effect of the hatch spacing parameter on the microstructure and mechanical properties of SA508 Gr.3 steel manufactured by laser powder bed fusion (L-PBF) for a nuclear pressure vessel. Materials were prepared with varying hatch spacing (0.04 mm [H4] and 0.06 mm [H6]). The H4 exhibited finer and more uniformly distributed grains, while the H6 showed less porosity and a lower defect fraction. The yield strength of the H4 material was higher than that of the H6 material, but there was a smaller difference between the materials in tensile strength. The measured elongation was 5.65% for the H4 material and 10.41% for the H6 material, showing a significantly higher value for H6. An explanation for this is that although the H4 material had a microstructure of small and uniform grains, it contained larger and more numerous pore defects than the H6 material, facilitating stress concentration and the initiation of microcracks.

1. Introduction
2. Experimental Section
3. Results and Discussion
4. Conclusion
Funding
Conflict of Interest
Data Availability Statement
Author Information and Contribution
Acknowledgments
References

• 황원구(인하대학교 신소재공학과) | Yuanjiu Huang (Department of Materials Science and Engineering, Inha University, Incheon 22212, Republic of Korea)
• 이기안(인하대학교 신소재공학과) | Kee-Ahn Lee (Department of Materials Science and Engineering, Inha University, Incheon 22212, Republic of Korea) Corresponding author
• 류호진(한국과학기술원 원자력 및 양자공학과) | Ho Jin Ryu (Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon, 34141, Republic of Korea)