Material volume reduction for creep testing using composite cantilevers and its application for residual life assessment

Hijazi, F and Pavan, AHV and Jayaram, V and Kumar, P (2024) Material volume reduction for creep testing using composite cantilevers and its application for residual life assessment. In: Materials Science and Engineering: A, 918 .

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Abstract

Digital image correlation (DIC) and finite element analysis (FEA) demonstrate that creep deformation in bending occurs primarily in �30 of the cantilever volume near the fixed end, especially when the creep stress exponent ranges from 5 to 7. As an alternative approach to minimize the material volume required for testing, the concept of fabricating composite cantilevers is proposed and validated in this study. A composite cantilever sample consists of an �active� creeping portion (e.g., T22 boiler steel) and an additively extended �passive� non-creeping portion (e.g., IN718). The volume reduction process involved varying the length of the �active� section, a, while keeping the total length of the cantilever, L, constant. The DIC measurements conducted at 600 °C to assess the creep behavior of T22 steel revealed that analytical expressions for monolithic cantilevers could aptly predict the constitutive steady-state creep laws from the composite cantilevers if measurements are made in a region at a critical distance away from the interface. FEA indicates that accurate stress estimation enables predicting monolithic creep behavior using composite samples with �a/L� ratios of as small as 5 . Using the developed approach, the loss of creep resistance of T11 boiler steel that was in service for � 240,000 h was ascertained in high throughput fashion using a composite cantilever having only 30 vol of the �active� material. Guidelines to minimize the volume fraction of the �active� portion in the composite cantilever and the implications of the observations for estimating the residual life of in-service high-temperature components are discussed. © 2024 Elsevier B.V.

Item Type:	Journal Article
Publication:	Materials Science and Engineering: A
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to the Publisher.
Keywords:	Image correlation, Bending creep; Composite cantilever; Composite cantilever sample; Digital image correlations; High-throughput; High-throughput creep testing; Life assessment; Residual life; Residual life assessment; Volume reductions, Creep testing
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	21 Nov 2024 01:21
Last Modified:	21 Nov 2024 01:21
URI:	http://eprints.iisc.ac.in/id/eprint/86817

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