Magnetic Properties of Cyclically Tensile-Deformed Steel 09G2S Manufactured by Selective Laser Melting

Abstract

Tests for low-cycle fatigue in the elastic-plastic deformation region of samples made of 09G2S steel prepared on a 3D laser printer by selective laser Melting (SLM-steel) were carried out. The major hysteresis loops and field dependences of the reversible magnetic permeability were measured. It was found that normalization at 980°C (1 h) reduces the tensile strength of SLM steel 09G2S by 2 times (${{\sigma }_{{\text{u}}}} = 502$ MPa) and increases the elongation by almost 6 times ($\delta = 34.6\%$), bringing this steel closer to cast steel 09G2S. The magnetic properties (${{H}_{{\text{c}}}},\;{{B}_{{\text{r}}}},\;{{\mu }_{{\max }}}$) of cast and SLM-normalized steel before and after cyclic tests are similar. The main changes in these properties of both cast and SLM steel are observed at the initial stage of low-cycle tests; a further increase in the number of cycles (up to the destruction of the test samples) does not lead to any considerable change in them. The nature of the change in the magnetoelastic field ${{H}_{\sigma }}$ determined from the experimental field dependences of reversible magnetic permeability during low-cycle tests for cast and SLM steels is radically different: for cast steel 09G2S, the magnetoelastic field ${{H}_{\sigma }}$ practically does not change with increasing the number of cycles, whereas for steel 09G2S manufactured using selective laser melting, there is a sharp increase in the value of ${{H}_{\sigma }}$ by 30% during the first test cycles that is most likely due to an increase in residual stresses.