Version 1
: Received: 27 June 2024 / Approved: 1 July 2024 / Online: 1 July 2024 (14:46:37 CEST)
How to cite:
Altshuler, T. L. Brittle Fracture of Iron and Steel and the Sharp Upper Yield Point are Caused by Cementite Grain Boundary Walls. Preprints2024, 2024070072. https://doi.org/10.20944/preprints202407.0072.v1
Altshuler, T. L. Brittle Fracture of Iron and Steel and the Sharp Upper Yield Point are Caused by Cementite Grain Boundary Walls. Preprints 2024, 2024070072. https://doi.org/10.20944/preprints202407.0072.v1
Altshuler, T. L. Brittle Fracture of Iron and Steel and the Sharp Upper Yield Point are Caused by Cementite Grain Boundary Walls. Preprints2024, 2024070072. https://doi.org/10.20944/preprints202407.0072.v1
APA Style
Altshuler, T. L. (2024). Brittle Fracture of Iron and Steel and the Sharp Upper Yield Point are Caused by Cementite Grain Boundary Walls. Preprints. https://doi.org/10.20944/preprints202407.0072.v1
Chicago/Turabian Style
Altshuler, T. L. 2024 "Brittle Fracture of Iron and Steel and the Sharp Upper Yield Point are Caused by Cementite Grain Boundary Walls" Preprints. https://doi.org/10.20944/preprints202407.0072.v1
Abstract
Brittle fracture of iron and steel above twinning temperatures are caused by cementite grain boundary wall cracks. These were revealed by an Atomic Force Microscope. At temperatures below the Ductile-Brittle Transition, cracks must propagate longitudinally within the cementite walls until the stress is sufficient high for the cracks to propagate across ferrite grains. Calculations using these concepts correctly predict the stress and temperature at the Ductile-Brittle Transition required for fracture to occur. At temperatures above the Ductile-Brittle Transition for hypoeutectoid ferritic steels, dislocations must fracture these walls transversely for plastic deformation to continue. This is responsible for the upper yield point at the elastic limit in these steels followed by a large drop in stress to the lower yield point. Here the walls surround completely all of the grains. Where the walls are segmented such as in iron, dislocations can pass around the walls resulting in a gradual change from elastic to plastic deformation. The Cottrell atmosphere theory of yielding is not supported experimentally. It was the best available until later experiments including those using the Atomic Force Microscope were obtained. Methods are presented here giving yield strength versus temperature and also the parameters for the Hall-Petch and Griffith equations.
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
