This paper intends to present the development of a Charpy V-notched (CVN) mastercurve to fit and/or extrapolate the transition curve of ferritic steels (including martensitic, bainitic and ferritic materials).
The purpose of a mastercurve is to define a general mathematical model able to represent the overall behaviour:
• of a material for different test conditions,
• or for a set of materials for given tests conditions.
The role of a mastercurve is then to allow extrapolating or interpolating values from other data on the basis of a robust model, thereby permitting to avoid execution of new tests. It is in general based on practical general observations and research for a common behaviour through a large database of experimental results.
This kind of approach is largely used to fit fracture mechanics data and can also be used in the case of Charpy toughness. Some changes have to be performed in order to take into account specificities of Charpy (such as dependence of transition slope with strength of materials) as well as some verifications linked to statistical distribution of failure probability.
This work is based on the assessment of a very large database collected for years at Industeel’s Research Center (tensile results, Charpy transition curves). This database represents 286 Charpy V-Notched transition curves of ferritic steels. It covers a wide range of materials and applications. Yield strengths of studied materials are ranging from 290 to 1180MPa while ultimate tensile strengths are in the range of 480 to 1690MPa.
The target of this mastercurve is to predict the correct shape of the CVN transition curve with a reasonable safety margin on the basis of a limited amount of data (tensile properties at room temperature at least and when available, few Charpy data).
A brief description of the database used within this study is given in the first part of this contribution as well as a description of the concept and underlying models. Finally, a validation of the work will be given as well as an illustration of its performance in a practical industrial case.