Analysis of test results under static load conditions of 316L steel

Abstract

Metal powder 3D printing technology is gaining popularity due to the possibility of producing structural elements of complex geometry, which production with the methods used so far is difficult or impossible to obtain. An example of a material used in the parts production by the additive method is 316L steel, which is used in the production of bone support screws, surgical tools and needles, or in other industries for the production of exhaust manifolds, parts of furnaces or heat exchangers. The study investigated the mechanical properties, hardness and microstructure of 316L steel produced in the selective laser melting process (SLM). Based on the tests, the following mechanical properties of 316L steel were obtained: Su = 566.7MPa, Sp0.2 = 484MPa, E = 113820MPa, A = 79.5%, Z = 72.3%. The hardness test results show a significant increase in hardness as the tensile test approaches the sample fracture. The structure of 316L steel in the grip part is characterized by the formation of visible semi-elliptical zones of the material alloy, the pools with crystallized grains with a cell-column structure oriented in the direction of the thermal gradient. This type of microstructure is characteristic of technology in which, after solidification, the cooling process takes place at high speed.

Diagnosis of fatigue cracks in structural elements manufactured by additive manufacturing

“…The cracking pattern of samples subjected to static loads and the microstructure of the Ti6Al4V alloy produced in AM were described in earlier works [4,7]. In paper [8], defects in the microstructure of additively manufactured 316L steel were described. The defects occurring in the structural elements produced by AM affect the early appearance of fatigue cracks.…”