Quality control of large-sized alloy steel parts fabricated by multi-laser selective laser melting (ML-SLM)

• Published in: Materials & design 2022-11, Vol.223, p.111209, Article 111209
• Main Authors: Liu, Jue, Dong, Shiyun, Jin, Xin, Wu, Pengyue, Yan, Shixing, Liu, Xiaoting, Tan, Yonghao, Li, Chaojiang, Xu, Binshi
• Format: Article
• Language: English
• Subjects: Alloy steel; Bench test; Brake disc; Large-sized part; Multi-laser selective laser melting
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.111209

[Display omitted] •An integrated method is proposed to improve the forming quality of large-size alloy steel parts fabricated by ML-SLM.•Optimize process parameters of 24CrNiMo taking into account forming quality and productivity of large-sized parts.•Specimens in different regions and statuses have good consistency in the mechanical properties for ML-SLM.•Bench test reveals SLM-disc meets harsh working conditions due to better tribological properties and more uniform temperature distribution. Additive manufacturing of large-sized parts remains challenging due to large residual stress and performance consistency. In this paper, a method of combining process, structure and performance was proposed to control the forming quality, and the brake disc for high-speed railways was chosen as a validation example. Meanwhile, multi-laser selective laser melting (ML-SLM) was adopted to prepare large-sized products. Research mainly includes process parameters optimization, mechanical properties distribution, and structural design. Process parameters of 24CrNiMo were optimized by exploring the influence of laser power and scanning speed on porosity, pore characteristics, and forming efficiency. Results show excessive heat input could reduce forming quality, causing an increase in either porosity or pore size. Mechanical properties research reveals that 24CrNiMo parts fabricated by ML-SLM have good consistency and overcome the strength-toughness tradeoff. The ultimate tensile strength reached 1255.25 MPa and impact energy was 101 J for single-laser regions. Furthermore, the new brake disc was redesigned with an innovative hollow self-supporting heat rib structure to enable a lightweight design and simplify post-processing. Finally, the qualified product was produced, and bench tests showed SLM-disc had higher performance. The work shows this method is effective and provides an engineering example for large-sized parts fabricated by ML-SLM.