G115 steel was jointly developed by China Iron & Steel Research Institute Group Co.,Ltd.and Baosteel for usage in 600-650 ℃ ultrasupercritical boiler tubes.Using a hot extruded G115 tube,creep tests were conducte...G115 steel was jointly developed by China Iron & Steel Research Institute Group Co.,Ltd.and Baosteel for usage in 600-650 ℃ ultrasupercritical boiler tubes.Using a hot extruded G115 tube,creep tests were conducted under a constant stress of 130 MPa and temperatures of 625,650 and 675 ℃.Comparing creep curves under different temperatures,it is observed that the creep performance of a G115 tube is more sensitive to temperature than stress.Steady-state creep rates of creep specimens are significantly increased by enhancing the temperature.A micro-structural analysis of ruptured creep specimens under a stress of 130 MPa and temperatures of 650 ℃ and 675 ℃ was performed;the fracture mechanism of creep specimens under these two temperatures mainly included the appearance of creep holes on the grain boundary and a decrease in the martensite lath density.展开更多
The infamous type Ⅳ failure within the fine-grained heat-affected zone (FGHAZ) in G115 steel weldments seriously threatens the safe operation of ultra-supercritical (USC) power plants.In this work,the traditional the...The infamous type Ⅳ failure within the fine-grained heat-affected zone (FGHAZ) in G115 steel weldments seriously threatens the safe operation of ultra-supercritical (USC) power plants.In this work,the traditional thermo-mechanical treatment was modified via the replacement of hot-rolling with cold rolling,i.e.,normalizing,cold rolling,and tempering (NCT),which was developed to improve the creep strength of the FGHAZ in G115 steel weldments.The NCT treatment effectively promoted the dissolution of preformed M_(23)C_(6)particles and relieved the boundary segregation of C and Cr during welding thermal cycling,which accelerated the dispersed reprecipitation of M_(23)C_(6) particles within the fresh reaustenitized grains during post-weld heat treatment.In addition,the precipitation of Cu-rich phases and MX particles was promoted evidently due to the deformation-induced dislocations.As a result,the interacting actions between precipitates,dislocations,and boundaries during creep were reinforced considerably.Following this strategy,the creep rupture life of the FGHAZ in G115 steel weldments can be prolonged by 18.6%,which can further push the application of G115 steel in USC power plants.展开更多
文摘G115 steel was jointly developed by China Iron & Steel Research Institute Group Co.,Ltd.and Baosteel for usage in 600-650 ℃ ultrasupercritical boiler tubes.Using a hot extruded G115 tube,creep tests were conducted under a constant stress of 130 MPa and temperatures of 625,650 and 675 ℃.Comparing creep curves under different temperatures,it is observed that the creep performance of a G115 tube is more sensitive to temperature than stress.Steady-state creep rates of creep specimens are significantly increased by enhancing the temperature.A micro-structural analysis of ruptured creep specimens under a stress of 130 MPa and temperatures of 650 ℃ and 675 ℃ was performed;the fracture mechanism of creep specimens under these two temperatures mainly included the appearance of creep holes on the grain boundary and a decrease in the martensite lath density.
基金financially supported by the National Key R&D Program of China(No.2022YFB3705300)the National Natural Science Foundation of China(Nos.U1960204 and 51974199)the Postdoctoral Fellowship Program of CPSF(No.GZB20230515)。
文摘The infamous type Ⅳ failure within the fine-grained heat-affected zone (FGHAZ) in G115 steel weldments seriously threatens the safe operation of ultra-supercritical (USC) power plants.In this work,the traditional thermo-mechanical treatment was modified via the replacement of hot-rolling with cold rolling,i.e.,normalizing,cold rolling,and tempering (NCT),which was developed to improve the creep strength of the FGHAZ in G115 steel weldments.The NCT treatment effectively promoted the dissolution of preformed M_(23)C_(6)particles and relieved the boundary segregation of C and Cr during welding thermal cycling,which accelerated the dispersed reprecipitation of M_(23)C_(6) particles within the fresh reaustenitized grains during post-weld heat treatment.In addition,the precipitation of Cu-rich phases and MX particles was promoted evidently due to the deformation-induced dislocations.As a result,the interacting actions between precipitates,dislocations,and boundaries during creep were reinforced considerably.Following this strategy,the creep rupture life of the FGHAZ in G115 steel weldments can be prolonged by 18.6%,which can further push the application of G115 steel in USC power plants.
