The fracture and fragmentation behaviour of additively manufactured stainless steel 316L

Abstract

Abstract.Expanding cylinder experiments using a gas gun technique allow investigations into the ductility of metals and the fracture and fragmentation mechanisms that occur during rapid tensile failure. These experiments allow the radial strain-rate of the expansion to be varied in the range 10 2 to 10 4 s -1 . Presented here is a comparative study of the fracture and fragmentation behaviour of rapidly expanded stainless steel 316L cylinders manufactured from either a wrought bar or additive manufacturing techniques. The results show that in the strain-rate regime studied, an additively manufactured cylinder failed at a higher strain and produced larger fragment widths when compared to cylinders manufactured from a wrought bar. In addition, an investigation into the role of macroscopic elongated voids that were introduced into the cylinder wall, at an angle of 45 to the cylinder radius, was undertaken. A comparison between experimental and simulated results (using the Eulerian hydrocode CTH) was also completed.

Fragmentation studies by non-explosive cylinder expansion technique

“…Fracture strain for AISI 1018 (similar to EN3) has been reported as 46%, at strain-rates of 10 5 s -1 . In another study of stainless steel cylinders by Amott (Amott et al, 2017), failure strain was reported at ca. 25% at a strain-rate of 8.5x10 3 s -1 .…”

“…In subsequent work, experimental and numerical studies on expansion and fragmentation of aluminium and titanium alloy cylinders were presented (Jones et al, 2013) including initial work on the effects of the cylinder temperature (Jones et al, 2014). These and other similar studies (Amott et al, 2017;Stirk et al, 2009) demonstrated the potential of gas-gun approaches. There are other methodologies that investigate cylinder expansion including electromagnetic tube expansion studies where the cylinder exhibits deformation due to the employment of a cylindrical coil (Qiu et al, 2018) Importantly, gas-gun driven cylinder expansion and fragmentation enables greater control over strain rates compared to explosive loading (as the impact velocity of the projectile can be precisely controlled), less risk for deployment of diagnostic instrumentation and the flexibility to carry out experiments in a laboratory environment.…”