Objective
THE HIGH STRENGTH LOW ALLOY STEELS ARE INCREASINGLY USED FOR CONTRUCTIONAL STEELWORK, OFFSHORE INDUSTRY AND FOR HEAVY MACHINE INDUSTRY ETC.
THESE STEELS HAVE EXCELLENT WELDABILITY CHARACTERISTICS IF THE RIGHT PRECAUTIONS ARE TAKEN INTO ACCOUNT. AS A PRECAUTION SAFEGUARDING AGAINST BRITTLE FRACTURE WELDMENTS IN THESE STEELS ARE OFTEN STRESS RELIEVED.
THE MOST COMMON METHOD FOR RELIEVING THE RESIDUAL STRESSES IS POST WELD HEAT TREATMENT (PWHT). THE BENEFICIAL INFLUENCE OF PWHT ON FATIGUE SHOULD NOT BE NEGLECTED, BECAUSE A SIGNIFICANT IMPROVEMENT IN FATIGUE ENDURANCE HAS BEEN OBSERVED AT R = -1.
BY FAR THE MOST EXPERIENCE EXISTS WITH PWHT AND THIS METHOD IS, WHENEVER APPLICABLE, WIDELY APPLIED IN PRACTICE.
HOWEVER, A NEED EXISTS FOR A GOOD ALTERNATIVE BECAUSE PWHT HAS SOME SIGNIFICANT DISADVANTAGES:
- HIGH COSTS,
- IMPORTANT METALLURGICAL CONSEQUENCES FOR THE PLATE MATERIAL, THE HAZ AND WELDMETAL PROPERTIES,
- LACK OF DIMENSIONAL STABILITY.
- PWHT IS NOT ALWAYS APPLICABLE.
A VIBRATION STRESS RELIEF (VSR) MAY BE A SUCCESSFUL ALTERNATIVE. THIS METHOD CONSISTS IN THE EXCITATION OF DEFINITE VALUE BY MEANS OF A MECHANICAL VIBRATION WITH A RESONANCE FREQUENCY.
THESE VIBRATIONS ARE GRADUALLY DECREASED AT CRITICAL PLACES WITH A HIGH STRESS LEVEL. INDUCED LATTICE VIBRATIONS ALLOWS THE DISLOCATIONS TO REARRANGE AND THE ATOMS TO MIGRATE ON A SMALL SCALE, SO THE MICROSTRESSES ARE REDUCED TO A STABLE LEVEL.
THE RELIEF OF STRESSES SEEMS TO BE VERY EFFECTIVE AT RESONANCE FREQUENCIES (100 HZ) AND TAKES ABOUT 10-60 MINUTES.
SIGNIFICANT ADVANTAGES ARE:
- REDUCTION OF CAPITAL OUTLAYS,
- DECREASE OF LABOUR CONSUMPTION,
- LESS POWER CONSUMPTION,
- ABSENCE OF SCALE ETC.,
- NO DETERIORATION OF THE TOUGHNESS PROPERTIES,
- ALSO APPLICABLE TO JOINTS IN DISSIMILAR METALS,
- INDEPENDENT OF DIMENSIONS.
THE USERS OF STEELWORKS ARE INCREASINGLY INTERESTED AND CONFRONTED WITH VRS METHODS-PRODUCTS INSTEAD OF PWHT.
HOWEVER THERE IS DOUBT ABOUT THE RELIABILITY. THERE ARE INDICATIONS THAT THIS TECHNIQUE IS NOT EFFECTIVE ENOUGH IN REDUCING RESIDUAL STRESSES, AND THAT MICROSCOPIC FLAW INITIATION MAY OCCUR.
A RESEARCH PROGRAMME IS PROPOSED TO COMPARE VSR AND PWHT. FURTHERMORE THE INFLUENCE OF REPAIR-WELDING ON THE FITNESS FOR PURPOSE (FATIGUE PROPERTIES) WILL BE INVESTIGATED.
THIS STRONGLY GROWING INTEREST FOR REPAIR WELDING OF CONSTRUCTIONS IS CONNECTED AMONG OTHER THINGS WITH THE FOLLOWING FACTORS:
- THE RISKS AND ECONOMICAL CONSEQUENCES LINKED WITH THE BREAK-DOWN OF A CONSTRUCTION ARE VERY LARGE. FOR THAT REASON INCREASINGLY STRONGER REQUIREMENTS ARE STIPULATED FOR STEEL STRUCTURES (FOR EXAMPLE FREQUENT INSPECTION WITH SOPHISTICATED NON-DESTRUCTIVE INSPECTION METHODS) RESULTING IN AN INCREASING NECESSITY FOR REPAIRING.
- THE ECONOMICAL LIFE OF ANY CONSTRUCTIONS IS INCREASED DURING THE LAST DECADE.
- THE IN-SERVICE CONDITIONS HAVE OFTEN BECOME MORE SEVERE (OFF-SHORE STRUCTURES, HEAVY MACHINE INDUSTRY).
FROM A PRACTICAL POINT OF VIEW REPAIRING HAS TO BE DONE UNDER DIFFICULT CIRCUMSTANCES (HIGH RESTRAINT, WELDING PERFORMANCE, ETC.) WITH THE RESULT THAT STRESS RELIEVING TREAMENTS ARE DESIRABLE TO IMPROVE THE PROPERTIES OF THE REPAIRWELDS AND TO ENHANCE THE FITNESS FOR PURPOSE.
HOWEVER POSTWELD HEAT TREATMENT IS NOT ALWAYS POSSIBLE. FOR EXAMPLE FOR REPAIRED WELDED COWPERS VSR IS THE ONLY POSSIBILITY TO RELIEVE RESIDUAL STRESSES. VSR IS ALSO INCREASINGLY BEING USED FOR MACHINED COMPONENTS IN HEAVY APPARATUS INDUSTRY.
SO FAR, ONLY ON A LIMITED SCALE, LESS SYSTEMATIC RESEARCH OF REPAIRED CONSTRUCTIONS HAS BEEN CARRIED OUT. FOR REASONS OF AN INCREASED APPLICATION AND OF ADVANTAGES OF THE RELIABILITY IT IS PROPOSED TO CARRY OUT THE RESEARCH ON REPAIRED WELDS.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
This project has not yet been classified with EuroSciVoc.
Be the first one to suggest relevant scientific fields and help us improve our classification service
You need to log in or register to use this function
Programme(s)
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Topic(s)
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Data not available
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Call for proposal
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Data not available
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Funding Scheme
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Data not available
Coordinator
64289 DARMSTADT
Germany
The total costs incurred by this organisation to participate in the project, including direct and indirect costs. This amount is a subset of the overall project budget.