Research progress on residual stress and microcrack control of tungsten fabricated via additive manufacturing

Abstract

This paper systematically investigates the critical challenges in metal additive manufacturing (AM) technology for producing tungsten first wall components in nuclear fusion reactors—namely, residual stress and microcrack control. Research indicates that tungsten's high melting point (3422 °C) combined with AM's rapid cooling characteristics (10³-10⁴ K/s) results in melt pool temperature gradients exceeding 10⁶ K/m, inducing significant residual stresses. while the material exhibits a sharp decline in plasticity within the brittle-to-ductile transition temperature range of 450–650 K, making residual tensile stresses (>100 MPa) prone to triggering microcracks. Synergistic regulation through optimized scanning strategies (e.g., adjusting scan paths and energy distribution) and post-processing techniques achieves the following: Surface strengthening techniques (e.g., laser shock peening) form a 100–300 μm compressive stress layer, significantly reducing microcrack density; High-temperature heat treatment (1200–1400 °C) promotes crack healing through grain boundary migration. Data-driven machine learning methods enable real-time residual stress prediction, supporting intelligent process optimization. Future efforts should integrate multiscale simulations with irradiation experiments to validate and advance the engineering application of tungsten components in fusion reactors.