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

Connection Between Internal Structural Stresses of the Istand the IIndkind and Operational Reliability of the Boiler Heating Surface

“…A characteristic feature of the steel 12H1MF is a not very high stability of the austenite [2], low hardenability, large heterogeneity of the structure and properties across the section and the length of the steam lines, sewers, and other elements of the thermal and mechanical equipment , development of cracks, porosity, reducing long-term plasticity [3] and, as a result, stress corrosion cracking and intragranular corrosion. These circumstances have led to the fact that the estimated temperature of the steam was first lowered to 545 °C and then to 510 °C, and the pipes fleet life was reduced from 300 000 hours to 100 000 hours [4].…”