Objective
(A)BACKGROUND
The role of impurities as determinants in limiting the quality performance, service life, processability, fabrication and joining of metal products and components is well appreciated and metal cleanliness has been the subject of research for many years, though the emphasis has been upon steel alloys. A sample list of references is given at the end of this Annex.
Defects in some or many forms including porosity, solutes, cracks and segregates as well as inclusions are continually introduced and eliminated during manufacture and if present at the final stage can lead to rejection of a component or premature failure. They are common to all metals and bear upon all industrial sectors e.g. the presence of inclusions limits the fatigue-life of gas turbine discs in aero-engines, affects the processability of aluminium and steel-can body stock in packaging and automotive manufacture and the surface quality and machinability of cast ferrous and aluminium components for the automotive and valve industries.
While significant advances have been made in the understanding of a metal's cleanliness, its relationship with the manufacturing process and its effect on overall properties, there is now general recognition that much more needs to be done. It is becoming increasingly clear that the cleanliness of a metal that is acceptable today will not necessarily meet the standards of tomorrow and that as Japan and the US improve cleanliness, European companies will need to keep pace or risk losing competitiveness.
Technical exchange missions to the US have shown that a considerable effort is being mounted to improve the cleanliness of their metals and, for instance, they have major R&D programmes to reduce the inclusion content of their products for the gas turbine industries and the speciality metals and aerospace industries have similar programmes. Japan is known to be targeting a broad spectrum of metals with improved cleanliness for a variety of industry sectors. Detailed knowledge is lacking here compared with knowledge of events in the US.
The fact is that the performance requirements of metals are becoming evermore demanding since applications are becoming increasingly testing. Metal products nowadays need to satisfy not only the customer's existing needs, which in themselves require different levels of metal cleanliness, but future needs. Furthermore, the technologies still to be developed need to be anticipated. This means that a position needs to be reached where the relationship between a metal's cleanliness and its properties is fully understood scientifically, where component manufacturers can transfer that understanding into technical and economical processes and where end-users can design components whose cleanliness is not only consistent but whose quality and fitness for use is definable and guaranteed. This situation does not exist at the moment.
A study by the UK's Centre for the Exploitation of Science and Technology ("Competitive Metal Processing") in 1991 clearly established the link between the potential competitiveness of the metals supply and engineering industries and their ability to control cleanliness and identified significant opportunities for better and more competitive products in various metals through a range of industrial applications in the automotive, biomedical, packaging, aerospace, power (nuclear and non-nuclear) and defence sectors. The design, control and measurement of metal cleanliness was identified as being an important issue in the development of many wrought alloys, not only for safety critical applications but also for a whole range of less demanding applications. It also showed its increasing importance in cast and other near-net-shape products. To exemplify this, the cleanliness and consistency of cleanliness has recently been highlighted by Castings Technology International in the UK as being particularly important in the machinability of steel castings when high volume runs and computer-controlled machine boats are involved.
During the study, three Technical Advisory Groups, comprising industrialists and academics, consulted over 60 companies, representing manufacturers and users of metals, as well as research organizations and universities. Additionally they commissioned a study "Defects in Metallic Materials" by the UK's National Physical Laboratory where case studies were made on 45 applications of metals including steel, nickel-based alloys, noble metals, refractory metals, Titanium and other non-ferrous metals where cleanliness was a limiting factor in achieving optimum performance.
There is little doubt therefore that the manufacture of engineering components from alloys of the right cleanliness could improve the competitive position of many companies in Europe. End-users are increasingly sourcing their materials from the best suppliers often outside Europe, who can demonstrate competence in the basic understanding of their processes enabling such manufacture. This will continue to be the case in the foreseeable future since materials processing and engineering companies will continue to use metals in large quantities, given that newer
alternative materials are still some way off full realization. The world market for metals with improved properties and quality exceeds by far that for alternative materials even though the projected rate of growth is less (ref. Advanced Materials: Policies and Technologies, Challenges - OECD Paris 1990).
It is against this background that a COST action on "Cleaner Metals" is put forward. The work is particularly suited to COST since the problem is common to all countries and a programme is amenable to work-sharing in its truest sense, since both metal manufacturers and end-users have interest in, and facility for, participation. Whilst some overlap with other European initiatives is inevitable, given the broad nature of the subject, care has been taken in preparing this programme to minimize it. For instance, the assessment methods cited later address different problems from those encompassed in COST 501 (non-contact methods were not addressed) and no other initiative deals with the subject as a concerted action nor with "fitness for use" as a generic theme. Work within the ECSC steel R&D programme has mainly dealt with non-contact methods of cleanliness assessment for steel and has focused on the development of manufacturing techniques to minimize defects. Close relationships between actions will be kept with related activities through personal contacts and joint workshops.
(B)SCOPE OF THE PROJECTS AND GENERAL PROGRAMME OF WORK
The scope of the programme and the general programme of work flows from the opportunities available to clean metals and their application. It is limited to conventional grades of metal and not those requiring super cleanliness. In the course of its preparation an international meeting of 60 experts from 6 countries was held in London and additional written expressions of interest were received from a further 20 experts representing in total 10 countries. Since then, many discussions have been held with various experts and end-users throughout Europe. Expressions for the need for a COST action on the cleanliness of commercial grades of metal is particularly high in industry but also in academia and research organizations. Interest in a programme has been expressed by companies in the UK, France, Germany, Spain, Italy, Sweden, Finland, Netherlands and Belgium.
In the course of the various discussions, it has become clear that whilst much work has been carried out on the measurement of metal cleanliness, and the relationship between cleanliness and properties and performance in service, there are significant gaps in the scientific and technical knowledge base. Most of the present measurement techniques do not take full advantage of new technological developments and many of the established relationships are semi-empirical, which do not allow for specifying a metal with a fitness for use in a new application.
The general areas of work which have been identified as most important at this time are estimated to cost ECU 10 million over 4 years, equivalent to around 50 man yrs/yr (allowing for 5% running/operating costs and ECU 60 000 per year coordination costs). The proposed work packages will be finally decided by the Management Committee but will be centred upon:
Work Package 1 (Estimated Cost ECU 3 million)
Development of quantitative assessment methods for the inclusion content of metals; particularly inclusions below 200æm and extending to low volume fractions. Especially important are:
(a)Non-contact methods, primarily for use "on line" and possibly based upon a metal's characteristic acoustic, optical or magnetic properties etc., with a target inclusion size of 80-20æm.
(b)Metallographic and concentration methods for laboratory assessments, exemplified by selective matrix electrolytic dissolution.
Modern computational methods of signal analysis will be most important for (a).
Work Package 2 Ferrous Metals (estimated cost ECU 4 million)
The relationship of the total morphology of impurities with microstructure, including grain boundaries, with mechanical properties and fitness for use and the scientific reasons for such relationships.
Such properties include:
toughnessrupture ductility
fatigue strengthcreep rupture
magnetic susceptibilityhot workability
surface condition.
Work Package 3 Non-ferrous Metals (estimated cost ECU 3 million)
The relationship of the total morphology of impurities with microstructure, including grain boundaries, with mechanical properties and fitness for use and the scientific reasons for such relationships.
Such properties include:
toughnessrupture ductility
fatigue strengthcreep rupture
magnetic susceptibilityhot workability
surface condition.
In the case of work packages 2 and 3, three dimensional modelling may need to be developed to predict the influence of all microstructural features, including inclusions, on an advancing crack. The level of cleanliness and microstructural condition might then be related to fitness for purpose more effectively.
For grain boundaries, the proposed work includes the determination of the structure and composition of grain boundaries, the measurement of impurities segregating to grain boundaries and the relationship of structure and composition to grain boundary cohesion.
Inevitably these areas of research will lead to a reassessment of the levels of cleanliness achieved by present processes and the understanding of their effects and to the need for improvement in terms of control. But these are seen as possible longer-term objectives and, perhaps, the basis of a separate programme.
(C)TIMETABLE AND ORGANIZATION
It is anticipated that the programme will be over 4 years, each work package proceeding in parallel, with an evaluation review after the first 2 years. Milestones will be identified by the Management Committee depending upon the number and diversity of the projects submitted. Close liaison will be maintained between the ferrous and non-ferrous elements within work package 1 and between work packages 2 and 3 with yearly workshops to review overall progress. Three coordinators will be appointed by the programme's Management Committee to oversee the progress of the work packages and to ensure liaison between them and related activities in other European actions. Yearly reports (or more frequent as required) will be made to the Materials ad hoc Technical Committee of the Senior Officials and to the Management Committee, and a conference will be held when the action is completed. Provision will be made for scientific missions as allowed for by the COST administration, and, in evaluating projects, special attention will be paid to how the new technology will be transferred to industry and how it will be exploited.
Current status
The Action started on 19 June 1996. The research programme itself is expected to start before Summer 1997. The first Management Committee was held on 26 November 1996 in Brussels.
Activities are organised in three Working Groups :
WG on Development of quantitative assessment methods : it deals with the inclusion content of metals and particularly inclusions below 200um and extending to low volume fractions. The research projects will be focused on :
non-contact methods with a target inclusion size of 80-20um
metallographic and concentration methods for laboratory assessments
WG on Ferrous Metals : it deals with the relationship of the total morphology of impurities with microstructure, including grain boundaries, with mechanical properties and fitness for use, and the scientific reasons for such relationship.
WG on Non-ferrous Metals : it deals with the same aspects as the WG on Ferrous Metals but with reference to Non-Ferrous Metals.
Programme(s)
Call for proposal
Data not availableFunding Scheme
Data not availableCoordinator
1049 Brussels
Belgium