An Evaluation on Fracture Toughness in SUS304 at High Strain Rate Considering Process Zone

Shiguma Yoshida,Takeshi Iwamoto,F Gálvez Díaz-Rubio,D.A Cendón Franco

doi:10.1051/epjconf/202125003013

Abstract

Some research works report the relationships between transformation toughening and process zone. In SUS304, the reduction of transformation toughening at high strain rate is expected from the result of a small punch test. Currently, the process zone in SUS304 is fuzzily defined. Therefore, a consideration of damaging process is necessary in order to understand a fracture mechanism associated with transformation toughening and process zone. In this study, at first, tensile tests of pre-cracked sheet specimens made of SUS304 are conducted by the split Hopkinson pressure bar in order to understand the fracture mechanism phenomenologically at high deformation rate. During the test, a DC potential difference method is introduced to capture onset time of fracture.

Highlights

A mechanism of transformation toughening in ceramics is studied in the past
Sigl et al [1] simulate the relationship between a size of process zone and stress intensity factor in WC by introducing ductile phase around crack tip
It is considered that the transformation toughening induces the reduction of stress concentration around crack tip by an increase in a shielding effect

Summary

Introduction

Sigl et al [1] simulate the relationship between a size of process zone and stress intensity factor in WC by introducing ductile phase around crack tip From this result, it is considered that the transformation toughening induces the reduction of stress concentration around crack tip by an increase in a shielding effect. Talonen et al [3] report that martensitic phase is suppressed at high strain rate by conducting tensile tests targeted on a smooth specimen of SUS304 in a wide range of strain rate. Their results tell us that rate sensitivity of its fracture toughness gets negative because of heat generation. A DC potential difference method is introduced to capture onset time of fracture

Experimental principle and procedure

Detecting onset time of fracture

Experimental procedure

Result and discussion

Summary