Assessment of Creep Properties of Haynes 282 Weld Using Deformation Mechanism-Based True Stress Model

Creep test is conducted on Haynes 282 weldment in a temperature range from 704 to 788 °C at different stress levels. The creep rupture data obtained from the creep tests are presented in a traditional Larson–Miller parameter (LMP) plot, together with a wide range of test data reported in the literature on both Haynes 282 base metal and weldment. The deformation mechanism-based true stress (DMTS) model is then used to predict the creep life of Haynes 282 weld along with mechanism-partitioning information, which shows a very good agreement (R² > 0.98) with the experimental data. It also infers the fracture mode of each test condition (temperature and stress), which is corroborated by fractographic observations of the creep-tested specimens. Furthermore, the DMTS model is used to construct isothermal LMP versus stress (σ) curves at 700 °C, 760 °C, 788 °C and 927 °C. It is found that these curves deviate from the short-term creep test LMP correlation at large LMPs. The DMTS model challenges the presumption that \(\text{LMP}=T\left({C}_{\text{LM}}+\text{log}{t}_{r}\right)=f(\sigma )\) $\text{LMP}=T\left(C_{\text{LM}},+,\text{log},t_r\right)=f(\sigma )$ is a relation of one-to-one correspondence for creep design, where T is the absolute temperature, t_r is the rupture life, and C_LM is the Larson-Millar constant. This model offers a method of mechanism-informed long-term creep life prediction (> 10⁴ h) of Haynes 282 alloy and its weldment.