Fracture Areas Quantitative Investigating of Bending-Torsion Fatigued Low-Alloy High-Strength Steel

Wojciech Macek

doi:10.3390/met11101620

Abstract

In this study, the impact of pseudo-random non-proportional bending-torsion fatigue loadings proportion on the fatigue life and the fracture surface topography was analyzed. Investigation was carried out for 24 specimens made of S355J2 steel with 11 different ratios of maximum stresses λ. For these cases, after the fatigue tests, the surface topography measurements were carried out using an optical profilometer, using the focus variation method. Three fracture zones were analyzed for each specimen: (1) total; (2) propagation; (3) rupture, taking into account the root average square height Sq and void volume Vv parameters. The results pointed that ratio of maximum stresses λ is the most influenced on volume surface parameters represented by void volume at a given height Vv, in the rupture area. A new fatigue loading parameter P was used, depending on fatigue life T and ratio of maximum stresses λ, which shows very good correlation in 4th degree type of fit, to void volume Vv parameter for the rupture area.

Highlights

High-strength low-alloyed (HSLA) steels are often the optimal material due to their balanced economic properties and technical properties [1]
Cruces et al [3] as well as Pawliczek and Rozumek [4] studied multiaxial fatigue and fracture of this type of steel in their research. The importance of this issue is indicated by a large number of publications on fatigue and fracture of HSLA steels subjected to various kind treatments [5,6]
In previous research by most of the Researchers, areal surface topography was used for the manufacturing material measures [12,13,14,15]

Summary

Introduction

High-strength low-alloyed (HSLA) steels are often the optimal material due to their balanced economic properties and technical properties [1]. To present the classification of 11 combinations of loading levels, a scatter plot of maximum normal stress σmax and maximum shear stress τmax, grouped by 24 results of fatigue life T was generated (see Figure 3).

Results

Conclusion