Investigation on hot-dip aluminised and subsequent HIP′ped steel sheets

Tritium permeation can be reduced significantly by a suitable coating on the structural material. Since alumina has the capability of tritium permeation reduction the development of such coatings on ferritic martensitic steels by hot-dip aluminising of F82H-mod. steel sheets was already performed successfully. An improvement of these coatings were achieved by subsequent HIP'ping at 1040 degreesC for 0.5 h at 250, 500 and 750 bar and subsequently tempered at 750 degreesC for 1 h at 1 bar. All samples were investigated by means of metallographical examination, EDX line scan analysis and Vickers micro hardness measurements. The high pressure produced two observed changes: firstly, with increasing pressure the thickness of the FeAl phase increases and the thickness of the a-Fe(Al) phase decreases, and secondly the formation of pores could be suppressed. successfully. The Vickers micro hardness of the base material F82H-mod. is not influenced by the heat-treatment under pressure and is about 215 HV. (C) 2001 Elsevier Science B.V. All rights reserved.