A method for evaluating the stress–strain relationship of materials in the microstructural region using a triangular pyramidal indenter

^1. Presented at the Welding Structure Symposium, 18 November 2006.

Abstract

A method for evaluating the microstructural stress–strain relationship of materials, using a triangular pyramidal indenter, is proposed in order to investigate the mechanical properties of steels and weld zones. An existing evaluation method, using a ball indenter, is correspondingly applied to the evaluation method using a triangular pyramidal indenter because the strain distribution under the indenter or the indentation curve on the unloading process between the ball and pyramidal indentation has a similarity. A corresponding ball indenter whose projection area is equal to that of the triangular pyramidal indenter is used to replace the triangular pyramidal indentation with the ball indentation, and the representative stress and strain that express the complicated deformation under the indenter are determined. The stress–strain relationships of single-phase steels in microstructural size are estimated by the proposed method, and on average correspond with those measured by macro-tensile tests. The difference in the stress–strain relationships due to the difference of the crystal orientation of each grain is possibly negligible with this method. It is expected to clearly estimate the difference in the stress–strain relationship of each phase in, for example, dual-phase steels by the proposed method.

Keywords:

• indentation test
• triangular pyramidal indenter
• ball indenter
• indentation curve
• stress–strain relationship
• microscopic heterogeneity

Notes

^2. Present address: Sumitomo Metal Industries, Ltd.

^1. Presented at the Welding Structure Symposium, 18 November 2006.

Additional information

Notes on contributors

Ryota Higuchi

2. 2. Present address: Sumitomo Metal Industries, Ltd.