Investigation into the Effect of Manufacturing Technology on the Fracture Toughness and Durability of Steam Pipes Made of 10Kh9MFB-Sh Steel

Abstract

Notched sample modeling was used to demonstrate effect of technology used for manufacturing pipes from steel 10Kh9MFB-Sh (piercing-broaching or electroslag remelting) on metal fracture toughness under creep conditions of 600°C at subcritical and avalanche stages of destruction. According to the subcritical crack growth and metal fracture toughness resistance determined on the samples, the lifespan of pipes having initial defects was evaluated. Calculations were carried out for pipes of two types including a hot reheat (HRH) steam line operating under a pressure of 4.1 MPa and a main steam (MS) line operating under a pressure of 14.0 MPa. Taking into account the obtained characteristics of fracture toughness, the use of electroslag remelting technology was shown to provide a durability of about 3 times that of piercing-broaching approaches. Differences in the pressure level and wall thickness shown to result in a tenfold increase in the durability of the HRH and MS steam pipelines at 600°C justify a different cracking risk classification, which should be taken into account in conducting operational monitoring.