ON THE FORMATION OF DOUBLE ZONES OF NECKING DURING HOT TENSILE TESTS

The phenomenon of double necking during hot tensile tests is discussed in this work. The investigation was carried out on high-carbon steel using a tensile testing machine equipped with an integral heating syst em. Tensile tests were performed in a large temperature range to obtai n the mechanical characteristic of the material. Microstructure evolut ion was observed by light microscopy and hardness measurements to dete rmine the position of double zones of necking, A significant increase in flow stress of as-transformed austenite was found to be at the orig in of the double necking behaviour.