Creep Life Prediction of 10CrMo9-10 Steel by Larson-Miller Model

Area of Science:

• Materials Science
• Mechanical Engineering
• Metallurgy

Background:

• Creep is permanent material deformation under sustained stress and temperature, leading to fracture.
• Experimental creep testing is time-consuming and expensive, necessitating predictive models.
• Engineering parameters and models are crucial for analyzing creep data and predicting material failure.

Purpose of the Study:

• To analyze and compare numerical algorithms for creep life prediction using the Larson-Miller parameter (LMP) extrapolation model.
• To investigate the impact of different extrapolation functions (linear, polynomial) and parameter C values on LMP predictions.
• To validate the chosen numerical algorithm against experimental creep rupture data for 10CrMo9-10 steel.

Main Methods:

• Calculations using the classical LMP equation with varying constant parameter C values.
• Application of a modified LMP equation with stress-dependent parameter C(σ).
• Investigation of linear and polynomial extrapolation and correlation functions for fitting the LMP model.
• Validation using creep rupture testing of 10CrMo9-10 steel at 600 °C and 80 MPa.

Main Results:

• Different values of parameter C significantly alter predicted time to rupture.
• Polynomial dependency with C=18 showed excellent LMP model response for temperatures 773-873 K.
• Stress-dependent C(σ) with linear fitting yielded promising but inconclusive results.
• Linear extrapolation with a constant C provided adequate time-to-rupture prediction at the validation stage.

Conclusions:

• Linear extrapolation with a constant parameter C is the most reliable method for predicting time to rupture in the validated conditions.
• For C=18, time to rupture was overestimated by ~8%; for C=20, it was underestimated by 27%.
• Other parameter C values and extrapolation methods resulted in prediction errors exceeding 50%.