Available online at www.sciencedirect.com *--0 **S‘ ScienceDirect JOURNAL OF IRON AND STEEL RESEARCH, INTERNATIONAL. 2012, 19(6): 42-46 Magnetic State of Deformed Austenite Before and After Martensite Nucleation in Austenitic Stainless Steels Gennadii V Snizhnoi’ , Mariya S Rasshchupkyna”‘ ( 1. Department of Micro- and Nanoelectronics, Faculty of Radio Device Engineering, Zaporizhzhya National Technical University, Zaporizhzhya 69063, Ukraine; Planck Institute for Intelligent Systems, Stuttgart 70569, Germany) 2. Department of Low-Dimensional and Metastable Materials, Max Abstract: The effect of the increase in the paramagnetic susceptibility of austenite up to the true value of the deforma- tion-induced martensite transition point E. has been experimentally established in steels X6CrNiTil8-10 (correspond- ing to AISI 321 steels). At this point nucleation and accumulation of martensite with the increase in the extent of de- formation but at a constant magnetic state of austenite takes place. Key words: magnetic measurement; austenitic stainless steel; plastic deformation; deformation-induced martensite One of the main features of austenitic stainless steels used in chemical industry, heat and atomic en- ergy industry is a possibility for realization of mar- tensitic 7- a transition in such steels under certain temperature-power conditions. Many of the indus- trial austenitic stainless steels are metastable and their main feature is that under conditions of plastic deformation martensitic 7-a’ transition takes place, where a’ is deformation-induced martensite having bcc structure“’. Numerous experiments have shown that nuclea- tion and accumulation of a’ martensite under condi- tions of plastic deformation begins on reaching some certain critical values of deformations ( strains ). Thus in various reference sources even for the same steel grade these critical values of deformations are ambiguous due to the fact that various methods for detecting martensite content, including magnetic ones, are not able to detect in paramagnetic austen- ite the amount of ferromagnetic martensite that is lower than 0. 5%. Therefore results obtained in the low concentration range should be considered ~arefull~’-~’. Despite thorough study of articles from multiple sources the authors did not success to find any infor- mation concerning a reliable method for measuring such low content of martensite described by other authors thanC6’. Quantitative content analysis of nucleating de- formation-induced martensite shows that the influ- ence of the magnetic moment of paramagnetic aus- tenite on determination of very low volume concen- trations of ferromagnetic martensite should be taken into accountC6’. This allows avoiding considerable errors since e. g. neglect of magnetization of para- magnetic austenite would cause an error value higher than 1000% at the a-phase content of 0.005% (in volume percent), the error value of 80% at 0.1% (in volume percent), and only when the a-phase content is in the range from 2. 5 , % to 3 % (in volume percent) the error value is about 3%. In the present study the authors used a sensitive magnetometric method that allows taking into ac- count magnetization of austeniteC6I. In this paper results concerning investigation of magnetic susceptibility of deformed austenite in fully pre-austenitized metastable chrome-nickel steel XGCrNiTil8-10 (analog of AISI 321) before nuclea- tion and after formation of the first and of the fol- lowing portions of deformation-induced martensite are presented. 1 Specimens Preparation and Experimental Technique The object of the present research is the indus- Bi0graphy:Gennadii V Snizhnoi(l966-), Male, Doctor, Senior Lectureship; Received Date: February 12, 2011 E-mail: rasshchupkynaBis. mpg. de;