Mechanical Behavior of Additively-Manufactured Gyroid Lattice Structure under Different Heat Treatments

Gyroid lattice structures, known for high stiffness and specific strength, are gaining attention for their energy absorption ability. However, energy absorption and strength of the gyroids are two desired properties, which vary contradictory. This study investigates manipulating properties on lattices using post-processing operation instead of modifying dimensions with consequent changes in weight and production cost. The challenge is that a particular post-processing heat treatment may improve one property, while it may be detrimental to other ones. The compressive properties of 17-4 PH stainless steel gyroid lattice structures fabricated using laser beam powder bed fusion (LB-PBF) method is investigated. Compressive properties such as load bearing capacity, crashing strength, and energy absorption are determined and the trends in their variation are discussed. Based on the experimental results, heat treating lattices with CA H900 procedure improves energy absorption and strength considerably, while increases crashing force, as well.