Statistical Size Effect in Fatigue Properties for Mini-Specimens.

Tomasz Tomaszewski

doi:10.3390/ma13102384

Abstract

The study verifies the sensitivity of selected construction materials (S235JR structural steel and 1.4301 stainless steel) to the statistical size effect. The P–S–N curves were determined experimentally under high-cycle fatigue conditions for two specimen sizes (mini-specimen and standard specimen). The results were analyzed using a probabilistic model of the three-parameter Weibull cumulative distribution function. The analysis included the evaluation of the technological process effects on the results based on the material microstructure near the surface layer and the macro-fractography. The differences in the susceptibility to the size effect validated the applicability of the test method to mini-specimen and showed different populations of the distribution of critical material defects.

Highlights

Structural and mechanical components under variable loads are susceptible to fatigue crack initiation and propagation
As probability that thethe material testtest results willwill be be distorted by the error due to the effects of the technological process used
The reason for the distorted by the error due to the effects of the technological process used

Summary

Introduction

Structural and mechanical components under variable loads are susceptible to fatigue crack initiation and propagation. Researchers suggest a newly developed test method based on non-standard specimens. The development of procedures to identify fatigue properties, cracking resistance, and propagation of fatigue cracking of materials used in nuclear reactors (small specimen test technique) is aimed at the use of mini-specimens with reduced volume due to limited irradiation volume and material availability [1,2,3]. The specimen miniaturization is required to test the local fatigue strength, allowing for the morphology of thin-walled material grains [4,5], different welded joint areas (seam, heat-affected zone, base metal) [6], limited microstructural properties of the material [7], or the reduction in fatigue test costs [8]. The technical capabilities of the fatigue tests (reduced load range) and the required cooling of the specimens (improved heat transfer) require small-diameter specimens [9]

Methods

Discussion

Conclusion