Clean Steel: Superclean Steel PDF

PREFACE 

The improved understanding of the factors leading to the long term in-service embrittlement of L.P. rotors which developed from basic research carried out in the 1970s enabled the late Bob Jaffee to formulate his ideas for the production of superclean steels. A history of the progress from experimental studies to actual rotors has been recorded in the proceedings of four previous workshops organised by the Electric Power Research Institute of Palo Alto, California, U.S.A.

The proceedings of the Fifth Workshop are recorded in the present volume which appears some three years after that of the Fourth Workshop.

The progress during the intervening period, as outlined in the twenty one papers presented, has been extensive. Not only have the properties of superclean 3.SNi-CrMo-V steels been thoroughly established, the economies of their production has been assessed and the extent of their use in the power generation industry has been recorded.

The concepts involved with the already developed superclean steels are applicable to a wider range of steels than the conventional 3.SNi-Cr-Mo-V varieties. Already some progress is now being made with the development of single shaft HP-LP rotor steels to a superclean specification and the same comment applies to the more highly alloyed 9-12% Cr steel, where, once again, low residual contents are found to alleviate the long-term embrittlement problems.

It is also clear that the superclean steels can be used for other than conventional power generation equipment. The use of these improved materials for general pressure vessels, nuclear components and the petro-chemical industry's pressure vessels is now becoming more widespread, where the requirement is to minimise inservice embrittlement at elevated temperatures. But, superclean steels also have excellent fracture toughness, at around ambient temperatures, with good stress corrosion resistance and these characteristics have led to the application in off-shore structures.

It is not surprising, therefore, that there is considerable interest in the future development and applications of superclean steels. Many views were expressed on these topics at a round table discussion, a summary of which is given in the proceedings.

The Editors of the proceedings are grateful to the other members of the organising committee for their unstinted help and to Miss Lisa Davies of The Institute of Materials, for her assistance as General Organiser of the Conference. Many others helped, but in particular, our thanks are due to Monsieur Andre Coulon, for his continued interest and advice.

We hope that the present volume will be looked upon as a further fitting tribute to the memory of the late Bob Jaffee.

Edited by: J. Nutting, R. Viswanathan