Journal Published Online: 08 November 2019
Volume 9, Issue 2

Hot Deformation Studies and Optimization of Hot Working Parameters in Custom 465® Martensitic Precipitation Hardenable Stainless Steel

CODEN: MPCACD

Abstract

Hot deformation studies and optimization of hot working parameters and corresponding microstructure control were explored in Custom 465® ultrahigh-strength precipitation hardenable martensitic stainless steel. Hot compression tests were carried out in the temperature range of 800°C–1,100°C and at five different strain rates (0.001–10 s−1). Processing maps were developed based on the results of hot compression tests, employing principles of the Dynamic Materials Model, and various domains of microstructure evolution (in the austenite phase) were identified. The stable and unstable domains as well as domains indicating dynamic recrystallization (DRx) were identified from the processing map. The domain for DRx was confirmed by detailed microstructural investigations (prior austenite grains) of the respective water-quenched specimens, as well as from the inflections in hardening curves. The optimum conditions for processing Custom 465 steel were suggested as T = 1,075°C and ϵ˙=103s1 and can be used for initial ingot breakdown (cogging) operations and T = 925°C and ϵ˙=103s1 for finish forging operations to obtain grain size control. The value of the activation energy for hot deformation was calculated to be 543.88 kJ/mol for this steel.

Author Information

Anoop, C. R.
Materials and Mechanical Entity, Liquid Propulsion Systems Centre, Valiamala Post Office (ISRO), Thiruvanathapuram, India
Singh, R. K.
Aerospace Materials Lab, Materials and Mechanical Entity, Liquid Propulsion Systems Centre, Valiamala Post Office (ISRO), Thiruvanathapuram, India
Kumar, Ravi Ranjan
Materials and Mechanical Entity, Liquid Propulsion Systems Centre, Valiamala Post Office (ISRO), Thiruvanathapuram, India
Jayalakshmi, M.
Materials and Mechanical Entity, Liquid Propulsion Systems Centre, Valiamala Post Office (ISRO), Thiruvanathapuram, India
Narayana Murty, S. V. S.
Materials and Metallurgy Group, Vikram Sarabhai Space Center (ISRO), Thumba Post Office, Thiruvananthapuram, India
Thomas Tharian, K.
Materials and Metallurgy Group, Vikram Sarabhai Space Center (ISRO), Thumba Post Office, Thiruvananthapuram, India
Pages: 18
Price: $25.00
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Stock #: MPC20190087
ISSN: 2379-1365
DOI: 10.1520/MPC20190087