Study on impact properties of creep-resistant steel thermally simulated heat affected zone

Abstract

The steam pipe line (SPL) and steam line material, along with its welded joints, subject to damage that accumulates during operation in coal power plants. As a result of thermal fatigue, dilatation of SPL at an operating temperature may lead to cracks initiation at the critical zones within heat affected zone (HAZ) of steam pipe line welded joints. By registration of thermal cycle during welding and subsequent HAZ simulation is possible to obtain target microstructure. For the simulation is chosen heat resisting steel, 12H1MF (designation 13CrMo44 according to DIN standard). From the viewpoint of mechanical properties, special attention is on impact toughness mostly because very small number of available references. After simulation of single run and multi run welding test on instrumented Charpy pendulum. Metallographic and fractographic analysis is also performed, on simulated 12H1MF steel from service and new, unused steel. The results and correlation between microstructure and impact toughness is discussed, too.