T/P92 (9CR-2W Steel) An Ideal Candidate for Advanced Boiler Tubes, Headers and Main Steam Pipes

摘要

The use of the W-content 9%Chromium ferritic steel introduced in 1995 in ASTM A213 and A335 as T92 and P92, is now extending more and more for advanced power boilers. A previous published paper (1) has presented first V&M TUBES* (*VALLOUREC & MANNESMANN TUBES) experiences with the Grade 92. The main aim of this paper is to give complementary metallurgical information including aging and creep properties and practical technical advises on the workability of tubes and pipe, namely cold bending, hot bending and different welding processes. The main advantages of Grade 92 appear to be: 1. very good creep properties competing with austenitic stainless steels and a price which is rather lower, 2. thermal fatigue, heat transfer and thermal expansion which are more favourable, allowing frequent start-up and shut-down of boilers. 3. workability and weldability which are similar to the well-known T91, therefore easier and cheaper than those of austenitic stainless steels. Thanks to its experience, V&M TUBES has now worldwide T/P92 references. Besides, in order to answer to the new market of power plants with very high thermal efficiency, V&M develops other new ferritic material including a 12%Cr steel with improved oxidation and creep behavior.