OPTIMIZATION OF HEAT TREATMENT OF CLOSED-DIE FORGINGS OF 2.5% MN STEEL

1 Bublíková Dagmar
Co-authors:
1 Jirková Hana 1 Jeníček Štěpán 1 Janda Tomáš
Institution:
1 University of West Bohemia, RTI – Regional Technological Institute, Univerzitní 22, 06 14 Pilsen, Czech Republic, EU, natasha@rti.zcu.cza, hstankov@rti.zcu.czb, jeniceks@rti.zcu.czc, jandat@rti.zcu.czd
Conference:
27th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 23rd - 25th 2018
Proceedings:
Proceedings 27th International Conference on Metallurgy and Materials
Pages:
634-640
ISBN:
978-80-87294-84-0
ISSN:
2694-9296
Published:
24th October 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
30 views / 8 downloads
Abstract

The forging industry seeks ways to improve mechanical properties of forged parts without using costly alloyed steels or complicated and time-consuming post-forge heat treatment. One of the available options is Q&P processing (Quenching and Partitioning) of advanced high-strength martensitic steels. The Q&P process is characterized by rapid cooling from the soaking temperature to a quenching temperature which is between the Ms and the Mf, and subsequent reheating to and holding at a partitioning temperature. Strength levels of more than 2000 MPa and elongation above 10 % can be obtained. Since the quench needs to be interrupted between the Ms and the Mf, new alloying strategies are being developed in order to depress the Mf below 100°C. With such steels, plain quenchants could be used, including boiling water.Using material-technological modelling, several heat treatment routes involving various cooling profiles were tested on three high-strength 2.5 % Mn steels with different Ni and Mo levels. The data for constructing the first model were acquired from a real-world treatment of a forged part. Quenching the forged part in boiling water and subsequent partitioning led to a strength of 2130 MPa and elongation of 12 %. Metallographic examination and measurement of mechanical properties were carried out on the experimental steels after the treatments.

Keywords: closed-die forgings, Q&P process, retained austenite, material-technological modelling
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