Open AccessEvolution of the tempered lath structure of the 12%Cr steels with low N and high B contents during creep
Author(s) -
Alexandra Fedoseeva,
Ivan Nikitin,
A. E. Fedoseev,
Rustam Kaibyshev
Publication year - 2021
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1014/1/012011
Subject(s) - lath , creep , tempering , materials science , martensite , metallurgy , stress (linguistics) , structural material , microstructure , composite material , linguistics , philosophy
9-12%Cr martensitic steels are promising materials for elements of boilers, tubes, pipes, heaters and steam blades for fossil power plants, which are able to operate at ultra-supercritical parameters of steam. Creep tests were carried out for two 12%Cr and 9%Cr steels at 650°C. After tempering at 750-770°C, a tempered lath structure was revealed in all the steels studied. The 12%Cr-Ta steel had the smallest lath width among the steels studied that provided the longest creep rupture time after creep test at 650°C/120 MPa. During creep, the applied stress causes the lath growth and the formation of subgrains instead of martensitic laths. The experimental sizes of subgrains and equilibrium subgrains, calculated on balance of driving and retarding forces and using the dependence of the size of subgrains on the applied stress during creep, were compared to estimate the contributions of secondary particles and applied stress to the growth of subgrains during tempering and creep in the different steels.