Ni-based heat-resistant alloy

Abstract

An Ni-based heat-resistant alloy which contains 0.15% or less of C, 2% or less of Si, 3% or less of Mn, 0.03% or less of P, 0.01% or less of S, 15% or more but less than 28% of Cr, 3-15% of Mo, more than 5% but 25% or less of Co, 0.2-2% of Al, 0.2-3% of Ti, from fn to 0.08% of Nd, while satisfying 0 = 0.4Nd, and which additionally contains, if necessary, a specific amount of at least one element that is selected from among Nb, W, B, Zr, Hf, Mg, Ca, Y, La, Ce, Ta, Re and Fe, with the balance made up of Ni and impurities. (In this connection, fn = 1.7 10-5d + 0.05{(Al/26.98) + (Ti/47.88) + (Nb/92.91)}, wherein d represents the average crystal grain size ([mu]m) and each chemical symbol for an element represents the content (mass%) of the element. In addition, in cases where W is contained, Mo + (W/2) = 15% is satisfied.) This Ni-based heat-resistant alloy has dramatically improved ductility after long-term use at high temperatures, and is capable of avoiding SR cracking that is a problem during repair welding and the like. Consequently, the Ni-based heat-resistant alloy is suitable for use as a pipe material, a thick plate for heat-resistant pressure-resistant members, a rod material, a forged article and the like in boilers for power generation, chemical industry plants and the like.

Description

technical field [0001] The invention relates to a Ni-based heat-resistant alloy. More specifically, it relates to a high-quality steel sheet that is excellent in hot workability, toughness and ductility after long-term use as pipes, heat-resistant and pressure-resistant parts, thick plates, rods, forgings, etc., in boilers for power generation, chemical equipment, etc. Strength Ni-based heat-resistant alloy. Background technique [0002] In recent years, in order to achieve higher efficiency, new construction of supercritical pressure boilers in which the temperature and pressure of steam have been raised has been promoted all over the world. [0003] Specifically, it is planned to raise the steam temperature from around 600°C to 650°C or higher, and further increase it to 700°C or higher. This is based on energy saving and efficient use of resources and reduction of CO in order to protect the environment 2 Gas emission has become one of the means to solve energy problems...

AI Technical Summary

Problems solved by technology

[0006] Fe-based alloys such as austenitic stainless steels have insufficient creep rupture strength for the above stringent requirements

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