Validation and improvement in metallic material tensile models for small punch tests

The small punch (SP) test has been widely used in applications where conventional mechanical tests cannot be performed; this paper predicts the material strength from the SP test results by empirical correlations method. The yield strength (YS) and ultimate tensile strength (UTS) models serve to associate the load-displacement (LD) curves of SP tests with the stress-strain data of uniaxial tensile tests, and then, the feasibility of these models at different temperatures is investigated. Using the Pearson's correlation coefficient (PCC) method, the ideal strength equations are accessed from past studies for the cast superalloys, including ZG15Cr2Mo1, P91, 316H, and Hastelloy X, whereas the validation results of the additively manufactured (AM) GH4169 alloy are not satisfactory. As a result, considering the unique manufacturing process of AM GH4169, this paper develops a YS model with correlation coefficients higher than 90% between the calculated and actual values and proposes a UTS formula with estimation errors less than 3.5%. Furthermore, with the purpose of superior strength prediction results, the discussion of the SP test velocity reveals that 0.50 mm min(-1) had wide adaptability to various strength models and operating temperatures.