Open AccessIdentification of Precipitates in Cr-Mn-N Based Steel After Thermal Exposures
Author(s) -
Michal Ondruška,
Mária Dománková,
Miroslav Jáňa,
Milan Marônek
Publication year - 2014
Publication title -
vedecké práce materiálovotechnologickej fakulty slovenskej technickej univerzity v bratislave so sídlom v trnave/vedecké práce materiálovotechnologickej fakulty slovenskej technickej univerzity v bratislave so sídlom v trnave
Language(s) - English
Resource type - Journals
eISSN - 1338-0532
pISSN - 1336-1589
DOI - 10.2478/rput-2014-0027
Subject(s) - metallurgy , materials science , isothermal process , austenite , precipitation , microstructure , grain boundary , annealing (glass) , welding , austenitic stainless steel , corrosion , thermodynamics , physics , meteorology
The paper deals with the identification of precipitates in the Cr-Mn-N steels after thermal exposure. The purpose of the study is to clarify the M2N precipitation by isothermal annealing at the temperatures of 750 and 900 °C with a holding time of 5, 10, 30 min, 1 hr. and 10 hrs. Microstructure of austenitic steel was characterised by the typical presence of annealing twins. Stepwise etching was observed at the holding time of 5 and 10 minutes, but at the holding time of 30 minutes, secondary particles were precipitated at the grain boundaries. Corrosion tests revealed that holding time significantly affected steel structure. M2N is the dominant precipitate, but the occurrence of σ-phase was occasionally observed especially at the interface of discontinuous precipitation and austenitic matrix. Slight increase of hardness at the grain boundaries was caused due to the precipitation of secondary phases during isothermal holding. The maximum hardness of 294 HV was measured on the sample isothermally annealed at 750 °C and holding for 10 hrs. The research provides theoretical basis for the heat affecting of steels, such as, for example, in welding