New low alloy heat resistant ferritic steels T/P23 and T/P24 for power plant application

Hydrogen pre-charging effects on the notch tensile properties and fracture behaviour of heat-affected zones of thermally aged welds between T24 and T92 creep-resistant steels

“…• C [9][10][11]. Microstructural evolution and mechanical properties of T24 steels during long-term ageing and/or creep exposure have been widely studied by many authors [10][11][12][13][14][15][16].…”

Numerical evaluation of the weldability of the low alloy ferritic steels T/P23 and T/P24

“…The physical properties and the oxidation resistance of the T/P23 and T/P24 are similar to the T/P22 due to the same basic compositions and structure, however, significant difference is obtained in mechanical properties and creep resistance. For instance, the values of yielding strength for T/P23 and T/P24 are almost two times higher than T/P22 in a wide range of temperature 3 . The addition of the elements V and Nb (V and Ti to the T/P24) which, combined with the elements C and/or N, can form carbides, nitrides or carbo-nitrides of MX type (M mean the metallic elements while X the expression C + N), that promotes a fine precipitation in the matrix, increasing the strength of the steels.…”

“…DOI: 10.1590/S1516-14392011005000019 Because of lower carbon content, T/P23 and T/P24 presents a martensitic structure with hardness limited to 350-360 HV10 that is compatible with hardness allowed for power generation application 4 . This behavior is very interesting in the case of thin-walled tubes (wall thickness < 10 mm) because it allows welding without post weld heat treatment (PWHT) and attain improved weldability [1][2][3][4][5][6][7][8][9][10] . The possibility of welding without PWHT and even preheating becomes the use of T23 and T24 very attractive since such procedures, although useful to improved the welded joint properties such as hardness and toughness, in practice can be diffi cult to carry out on services, increasing cost and can produce unconformities as structural distortion and reheat cracking.…”

“…In general, the ferritic Cr-Mo alloy steels for elevated temperature applications were improved by specific alloy addition such as V, Nb, W and N. Thus, the alloying addition to the T/P22 lead to the development of the modified low alloy ferritic steels T/P23 and T/P24 that have enhanced their properties at elevated temperature such as strength and creep resistance. Besides of enhanced performance at elevated temperatures, it is also claimed an improved weldability of the modified steels T/P23 and T/P24 [1][2][3][4][5][6][7][8][9][10] . Due to these characteristics, T/P23 and T/P24 steels are becoming very attractive for applications in power plants, petroleum refineries and petrochemical industry.…”

Roles of Molybdenum and Tungsten on Reheat Cracking Susceptibility of 2.25Cr Heat Resistant Steels

“…1) This concept has been applied to the development of the T/P24 (2.25Cr1MoVNbTi) from the T/P22 (2.25Cr1Mo) heat resistant steel.…”