Study on mechanical behaviour and microstructure evolution of wire-arc directed energy deposition Co-free maraging steel under dynamic compression

Abstract

The dynamic compression property of maraging steel is an important basis for determining the impact resistance of the structure, and the related studies are few. To enrich the relevant data and elucidate the relevant mechanisms, in this work, a new Co-free maraging steel component is fabricated by wire-arc direct energy deposition (DED), and the quasi-static tensile properties and dynamic compression properties are tested. The results show that the deposition direction exhibits the highest quasi-static tensile properties. Strain rate strengthening effect, grain refinement and grain boundary strengthening are the main strengthening mechanisms during dynamic compression. With the increase of strain rate, dynamic recrystallization intensifies, causing the grain size and dislocation density to decrease. Under dynamic condition, strain-induced martensite phase transformation reduces the austenite content; temperature rise and dynamic recrystallization limit the degree of martensite phase transformation. Strain rate sensitivity of the strength is independent of the direction.

Keywords

• Wire-arc directed energy deposition
• maraging steel
• dynamic mechanical behaviour
• microstructure evolution