Determination of high-temperature elastoplastic properties of welded joints by indentation test

Abstract

The stress and strain fields formed in the heat-affected zone (HAZ) of welds in pipes in thermal power plants has recently attracted attention as a key plant management issue. The microstructure in the HAZ changes locally as a result of the thermal history imposed by the welding procedure; these changes are manifested in the form of a stress–strain response different from that of the base metal. In the present study, a method based on indentation tests is proposed to estimate the variation of yield stress over the HAZ. The well-known indentation tests to infer the stress–strain curve from indentation load and penetration depth measurements are familiar. However, there are difficulties in applying this approach at high temperatures. An alternative procedure based on impression size is proposed and applied to evaluate the variation of mechanical properties of Grade 122 steel over the HAZ in a welded part at 873 K.

Keywords:

• Indentation test
• Mechanical property
• Welded parts
• HAZ
• High temperature