Materials and Fracture Mechanics Assessments of Railroad Tank Cars

Published

September 1, 1998

Author(s)

A Zahoor, G E. Hicho

Abstract

This report presents a review of fracture mechanics assessments and the mechanical and fracture toughness data for four steels used in the manufacture of railroad tank cars that carry hazardous materials. Thirteen reports developed between 1975 and 1995 by the National Institute of Standards and Technology (NIST, formerly NBS), Association of American Railroads (AAR) and Railroad Progress Institute (RPI)-AAR were reviewed and these are listed as References 1 through 13. These reports cover accidents and their investigations and analyses going back to the 1960's. Specifically, this report covers the review for the A212 steel, AAR TC 128 grade B, A515 grade 70, and an experimental steel A 8XX, a control-rolled steel. The materials data reviewed were the tensile strength and stress rupture data, CVN, DT, NDT, DWTT, FATT, J_Ic, CTOD, K_Ic, and K_Ia at tank car operating and accident temperatures. Where possible, the mechanical and fracture toughness data are organized in a tabular or graphical format to allow a quick comparison of properties for the four steels. The format can be useful in the developlment of materials data guidelines for use by the FRA staff.This report is organized primarily from a fracture mechanics evaluation perspective. A fracture mechanics evaluation involves calculation, estimation and availablility of two major elements: the crack driving potential of the structure and the crack resisting properties of the material. When the former exceeds the latter, the initiation of crack extension occurs. The crack will continue to extend if the crack driving potential is maintained above the material's resistance to crack extension. In some structures, the crack driving potential cannot be maintained due to inherent design features or some other flaw growth mechanism such as leak-before-break.

Citation

NIST Interagency/Internal Report (NISTIR) - 6266

Report Number

6266

NIST Pub Series

NIST Interagency/Internal Report (NISTIR)

Pub Type

NIST Pubs

Keywords

critical crack size, fracture, fracture mechanics, fracture toughness, mechanical properties, railroad, steel, tank car

Citation

Zahoor, A. and Hicho, G. (1998), Materials and Fracture Mechanics Assessments of Railroad Tank Cars, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed July 27, 2024)