ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 3 September 2009
Page Count: 13

Determination of ΔK_th by Compression Pre-Cracking in a Structural Steel

Carboni, M.
Dept. of Mechanical Engineering, Politecnico di Milano, Milano,

Patriarca, L.
Dept. of Mechanical Engineering, Politecnico di Milano, Milano,

Regazzi, D.
Dept. of Mechanical Engineering, Politecnico di Milano, Milano,

(Received 15 June 2009; accepted 4 August 2009)

Abstract

The traditional experimental procedures used to generate thresholds (known as “ΔK-decreasing” and “constant K_max”) have been challenged because it seems they affect the experimental results, sometimes in a non conservative way. In order to fix this problem, different experimental procedures (“compression pre-cracking constant amplitude” and “compression pre-cracking load reduction” (CPLR)) based on a compression-compression pre-cracking of fracture mechanics specimens have been proposed. Up till now, such procedures are not yet wide-spread between fracture mechanics experimentalists. In particular, due to the recent introduction, CPLR has been applied only to few cases: Al alloys, Ti alloys, and high strength steels (ultimate tensile strength>1300 MPa), all in the shape of M(T) or C(T) specimens subjected to positive stress ratios. The present paper deals with the application of these novel “compression pre-cracking” procedures, with particular attention to CPLR, to the unexplored and technically very important case of the structurally mild A1N steel grade (very commonly used to produce European railway axles) in the shape of SE(B) specimens subjected to stress ratios varying between −2 and 0.85.

Keywords:
threshold stress intensity factor range, compression pre-cracking, A1N steel grade

Paper ID: JAI102617
DOI: 10.1520/JAI102617
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