Evaluation of residual creep life of steels using macro-pillar creep testing and Omega method

• Published in: Measurement : journal of the International Measurement Confederation 2021-04, Vol.174, p.108991, Article 108991
• Main Authors: Zhang, Xiaocheng, Chen, Guoyao, Wang, Wulin, Zhong, Jiru, Wang, Qiongqi, Xu, Tong, Guan, Kaishu
• Format: Article
• Language: English
• Subjects: Creep life; Indentation; Omega method; Pillar
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2021.108991

[Display omitted] •An in-site test method for evaluating residual creep life of steels.•A less destructive test method than small sample methods.•Correction for barreling effect of a pillar under compression load.•Development of a creep testing machine. Residual creep life evaluation is an essential part of Fitness-For-Service (FFS) assessment for engineering components operating at elevated temperatures. This paper elaborates a new evaluation approach based on macro-pillar compression testing (MPCT) and Omega method. The MPCT creep test was performed at the same stress level as the tensile creep test by adjusting the testing load using an algorithm, which is also provided in this paper. The barreling effect of MPCT creep test was corrected by two proposed parameters, which were calibrated using finite element method with 6 types of Cr-Mo alloys from API 579. Finally, a 1.25Cr-0.5Mo-Si steel was prepared for both MPCT and round bar tensile creep tests at 550 ℃ and different initial stress levels. The predicted residual creep life by MPCT has an error of 2.2% at 140 MPa, 6.4% at 160 MPa and 13.5% at 180 MPa.