Mechanical properties of 8Cr-2WVTa steel aged for 30 000 h

A mill production plate of a reduced activation ferritic steel was thermall y aged for up to 30 000 h at 400-650 degreesC. Charpy impact tests, creep r upture tests and hardness tests were conducted. Both Vickers hardness numbe r and creep strength decrease with aging at 650 degreesC. The ductile-britt le transition temperature (DBTT) increases with both aging time and aging t emperature. However, the DBTT does not exceed +20 degreesC even after aging at 650 degreesC for 30 000 h. Extracted residues and extraction replicas w ere analyzed metallurgically The increase in DBTT is related mainly to the precipitation of Laves phase on the prior austenite grain boundaries. The r ather low DBTT after aging is caused by the fine prior austenitic grain siz e. (C) 2000 Elsevier Science B.V. All rights reserved.