May - June 1999
By joining Group Sponsored R&D Projects TWI Industrial Members gain access to substantial programmes at low cost, with the opportunity to steer work undertaken into areas of specific interest. The following GSPs have been, or are about to be, launched.
For a full list of proposed, active and closed projects see here
Polythionic acid attack stress corrosion cracking
Launched March 99, duration 2 years
Cost per sponsor £12 000 pa.
Project leader: A Leonard
Cracking can occur in refinery installations due to the action of polythionic acids on austenitic stainless steel components. Recommended practices to avoid the problem as in NACE RP0170 are based largely on control of the internal environment during shutdown conditions and uncertainty remains regarding the effects of material type, of thermal stabilisation practice, and of welding operations. These issues will be addressed, together with consideration of an appropriate test method, so that recommendations can be made regarding optimum fabrication procedure.
Equivalency and economics of high velocity oxy-fuel (HVOF) sprayed coatings
Joint TWI/EWI Project.
Launched March 99, duration 2 years
Cost per sponsor £15 000 pa.
Project leader: A Sturgeon
The HVOF spraying process is increasingly being used to prepare coatings of metallic alloys with very low levels of porosity and oxide, and which exhibit performances superior to those achieved with other thermal spraying processes. The selection of spraying parameters to achieve the optimum combination of coating properties and process costs is strongly influenced by the availability and cost of both fuel type and powder type. This project will determine the roles that fuel type, powder type and powder size distribution have on process costs, deposition rate and efficiency, coating porosity and oxide level for selected coating alloys.
Metal ceramic graded composite coatings by HVOF spraying for improved protection in corrosive environments
Launched September 98, duration 2 years
Cost per sponsor £15 000 pa.
Project leader: A Sturgeon
The high velocity oxy-fuel (HVOF) spraying process allows for the deposition of very low porosity, high quality coatings of ceramic and graded ceramic-metal materials. Because of their chemical stability and high hardness these coatings are attractive candidates for the protection, or repair, of components that experience high temperature corrosive environments, often with wear occurring. The aim of this project will be to determine how coating structures can be prepared by HVOF spraying that give optimum protection in realistic corrosive environments, and to measure both corrosion performance and coating costs.
Repair welding of modified 9Cr1Mo steels without postweld heat treatment
Launch July 99, duration 2 years
Cost per sponsor £10,000 pa.
Project leader: A Barnes
The increasingly widespread use of the modified 9Cr1Mo steels within the power generation industry, and the increased period of service, raises the likelihood for repair, either of fabrication flaws found during in-service inspection, material degradation, or accidental damage. Controlled deposition repair techniques, which avoid the necessity for PWHT, have yet to be developed for these steels, but potentially offer distinct economic and time advantages. This programme aims to develop and subsequently validate as-welded controlled deposition procedures for these higher alloy steels.
