Up to now interlaboratory studies on determination of T0,X at elevated loading rates were conducted using Precracked Charpy (PCC) specimens ( ASTM E1820, Annex A17) using Charpy machines with reduced velocity, ending up with loading rates of about dK/dt = 3x10^5 MPam s-1. Caused by the small specimen size and limitations coming from the 3- criterion for the force measurement, the possible temperature range is much smaller than the maximum of +- 50 C given by ASTM E1921. There are indications from various published results from larger specimens that there might be an impact of the loading rate on the threshold value Kmin, the real shape of the mastercurve and the statistical distribution, at least for some materials.In this case the determined T0,x might be shifted, if the chosen test temperatures differ much from T0,X. This is the motivation to start an ILS testing specimens with size of about 1 inch at elevated loading rates as contribution to the precision and bias statement of Annex A1 of ASTM E1921 Special Requirements for Determining the Reference Temperature, T0,X at Elevated Loading Rates.
Draft Under Development