Additive Manufacturing of Nickel-Based Superalloys for Aerospace Propulsion: Grain Boundary Engineering and Hot Isostatic Pressing Protocols in Chinese Aerospace R&D

• LPBF of non-weldable gamma-prime superalloys (CM247LC, IN738LC) requires build platform preheating to 800°C to suppress solidification cracking; without preheat, crack density exceeds 10 cm/cm². • Multi-stage HIP at 1,200°C/150 MPa for 4 hours, followed by rapid argon quenching, reduces porosity to <0.1% and transforms gamma-prime into a uniform cuboidal morphology, improving creep life by 3–5x over As-Built. • Optimized LPBF+HIP IN718/GH4169 achieves 1,050 MPa tensile yield strength and 18% elongation, matching cast-wrought properties; creep-rupture life at 950°C/150 MPa reaches 120 hours, versus 150 hours for conventionally cast. • HIP adds 30–40% component cost and 2–3 weeks lead time, but reduces scrap rates from 25% to <5% in pilot production runs. • Chinese aerospace R&D is prioritizing in-situ process monitoring and machine learning for defect prediction, aiming to reduce HIP dependency by 50% by 2026.