Sensitivity to Mn content mechanical properties of phase composition of ADI

Abstract

The effect of manganese content on the phase composition and mechanical properties was studied on ADI materials that are isothermally quenchеd at different temperatures. ADI samples with Mn content of 0.78% and 0.24% were analyzed. The final structure of the cast iron was created by austenitizing heating at 900 ° C for 30 minutes. and subsequent isothermal quenching in liquid tin at temperatures of 310, 330, 350, 380 ° C for samples with high manganese content and at 350, 370 ° C for samples with low content.  It is shown that increasing the manganese content increases the amount of residual austenite under the same quenching conditions. This enhances the positive role of the TRIP effect on the hardening processes. In particular, ADI with a high content of Mn show a higher rate of strengthening at the initial region of loading diagram, higher hardness and increased damping capacity. Instead, due to the embrittlement action of manganese, such materials have lower mechanical characteristics, which determined fracture moment. It was found that for the same quenching conditions, deformation to fracture and toughness are reduced by half on samples with higher manganese content. The negative effect of manganese on the fatigue is less significant, because the embrittlement action is compensated by phase transformations in the crack head, which inhibits its spread under cyclic loading. Due to the fact that manganese enhances the positive role of the TRIP effect but decrease fracture résistance, it is proposed to use ADI materials with high Mn content in products that operate in conditions of wear but are not subject to extreme stress.