Elastic property of aged duplex stainless steel

We have measured the elastic constants of duplex stainless steel, JIS-SCS14A (CF8M), aged isothermally at 400 C up to 10,000 h, using resonant ultrasound spectroscopy method. The elastic constant c11 (¼ k þ 2l) increases monotonically with the aging time, but c44 (¼ l) remains virtually unchanged. Using a micromechanics model, we have deduced the elastic constants of a-phase on the assumption that those of c-phase are unchanged with the aging. The increase of the a-phase elastic constants reflects the spinodal decomposition of a-phase. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.