Relationship between Charpy V-notch Impact Characteristics and Brittle Fracture Initiation Temperature in Deep Notch Test

Abstract

The relationship between Charpy V-notch impact characteristics and brittle fracture initiation characteristics in Deep Notch Test has been investigated.
The summary is as follows:
(1) Brittle fracture initiation temperature [Ti]C=40, when the applied stress becomes equal to the half value of yield strength and the crack length is 80mm, is related to Charpy V-notch 50% crystallinity transition temperature in the equation: [Ti]C=40=0.687α⋅Trs+7.83 √t -54(°K) where α is yield ratio and t is plate thickness.
The coefficient of correlation between measured values of [Ti]C=40 and estimated ones is 0.92.
(2) The required vTrs becomes more stringent with increasing strength and thickness when [Ti]c=40 is constant.
(3) For preventing brittle fracture in the weldment at-15°C, the estimated maximum heat input is 170 KJ/cm for 60 Kg/mm² class high strength steel, while it is 50 KJ/cm for 80 Kg/mm² class high strength steel.