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Materials for Internal Combustion Engine Pistons

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Development and Research of New Class of Microcrystalline Aluminum-Silicon Alloys for High-Resource and High-Strength Internal Combustion Engine Pistons

Tech Area / Field

  • MAT-ALL/High Performance Metals and Alloys/Materials

Status
8 Project completed

Registration date
04.07.2003

Completion date
05.02.2008

Senior Project Manager
Ryzhova T B

Leading Institute
State University of Nizhny Novgorod / Research Physical and Technical Institute, Russia, N. Novgorod reg., N. Novgorod

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Lawrence Livermore National Laboratory, USA, CA, Livermore

Project summary

Goal of the project is to develop and research a new class of microcrystalline (MC) Al-Si piston alloys with high-strain-rate superplasticity effect and enhanced mechanical properties.

The basic idea of the project is to combine new technologies in the field of Al-Si alloys modification, new methods for producing microcrystalline alloys by equal-channel angular pressing (ECAP) and the latest achievements in the area of high-strain-rate superplasticity (HSRS) investigations.

Scientific – and – technical potential of the participants.

The participants of the project have created all necessary prerequisites for successive solution of all project tasks. A great experience has been gained by Russian Federal Nuclear Center in producing new materials and in investigating their chemical and phase composition, structure and physical - mechanical properties. Extensive experience has been gained during the works in the field of the development and tests of nuclear weapons and military technologies. It is important to emphasize that RFNC-VNIIEF has experience in investigating superplasticity and HSRS of metals and alloys.

RPTI NNSU group is experienced and has scientific potential in experimental and theoretical investigation of nano- and microcrystalline materials and superplastic alloys. The group has gained a number of significant scientific results related to the project subject matter. In the field of theoretical investigations there were developed the theory of non-equilibrium grain boundaries, theories of material structural superplasticity, models describing physical-mechanical properties and structure evolution parameters of nano- and microcrystalline materials. New approach for describing HSRS phenomenon was developed allowing both to give theoretical description of HSRS regularities and to develop original methods for calculation and optimization of chemical, phase composition and microstructure parameters of materials in order to obtain superplasticity. In field of experimental investigations there were developed original methods for ECAP treatment of metals and alloys on the basis of ECAP technology, scientific bases of this technological process were created, there were developed some original methods for experimental investigation of mechanical and physical characteristics and also of the high-strain-rate superplasticity of nano- and microcrystalline metals and alloys.

Scope of Activities

The work will be carried out according to the following main directions:


1. Development of MC Al-Si piston alloys and optimization of their chemical composition.
2. Investigation of Al-Si piston alloys mechanical properties.
3. Investigation of Al-Si piston alloy structure.
4. Development of theoretical models.
5. Development of recommendations.
6. Preparation of working plans, interim and final scientific-and-technical reports, and scientific papers.

Meeting ISTC Goals and Objectives

Within the project scientists and specialists of RFNC-VNIIEF, involved into the development of the nuclear weapons, will have the possibility to change orientation of their abilities for peaceful activity in the field of creating new materials for internal-combustion engine pistons.

Project realization will give Russian scientists the possibility to carry our joint scientific investigations in cooperation with foreign collaborator – leading scientist in the field of nanostructured materials investigations.

ISTC support of the project works will make it possible to carry out applied and fundamental investigations and also the development of technology for obtaining microcrystalline aluminum alloys for manufacturing internal combustion engine pistons used in peaceful purposes.

The project has great commercial potential owing to the possibility to use microcrystalline Al-Si alloys in mass production of high resource pistons for internal combustion engine.

Technical Approach and Methodology

Task solution approaches and methodology for processing, superplastic deformation and investigating the structure and properties of metal alloys having various chemical and phase composition are based on the experience gained by RFNC-VNIIEF specialists, when solving the tasks related to the development of materials for assemblies of nuclear weapons, and on the experience of RPTI NNSU specialists gained when solving the problems of nano- and microcrystalline material experimental and theoretical investigation, when those materials are processed by severe plastic deformation methods, and when investigating superplasticity and HSRS.

In the basis of theoretical developments there are structural micromechanics methods, defect theory methods and also original models developed by the project authors for describing structural superplasticity processes, processes of microcrystalline material structure evolution and grain refinement processes.

In the basis of experimental investigations there are conventional and original methods of physical-mechanical characteristics investigation and methods of microstructure evolution investigation.

In the basis of technological developments there is great experience of RFNC-VNIIEF gained when solving a large number of the problems related to the development of materials for nuclear weapon assemblies.

RPTI NNSU and RFNC-VNIIEF have the basic equipment required to carry out the project works.

Expected Results and Their Application

As a result of the project work there will develop and produce a new microcrystalline Al-Si alloy for internal combustion engine high-strength pistons with high service life.

There will be developed a new method for producing microcrystalline Al-Si alloys exhibiting the effect of high-strain-rate superplasticity. These Al-Si alloys may be used in piston mass production applying superplastic forging technology.

The following scientific and technical results will be obtained within the project work:

1. Experimental results. There will be developed and researched new microcrystalline materials produced by ECA pressing method – piston aluminum alloys of Al-Si system. Results of experimental investigations of structure and physical and mechanical characteristics of the new Al-Si alloy in cast, powder and microcrystalline (MC) state. Results of experimental investigations of high-strain-rate superplasticity in MC Al-Si alloys. Research results of fatigue resistance in MC Al-Si alloys at room and operating temperatures.

2. Theoretical results. New physical models will be developed for describing MC Al-Si alloy structure and characteristics, including the models for describing characteristics of the grain boundaries and interphase boundaries, models for describing “stress-strain” dependence behavior and structure evolution during high-strain-rate superplasticity, models for describing structure evolution during ECA pressing deformation, models of fatigue crack initiation.

3. Technological recommendations.


- Recommendations for producing MC Al-Si alloys by ECA pressing providing a homogeneous microcrystalline structure with the grain size of 1 micron.
- Recommendations concerning optimum regimes of high-strain-rate superplasticity providing elongation-to-failure at least 400% at strain rate 10-1 s-1.
- Recommendations concerning optimal regimes of thermal treatment providing high fatigue resistance at room and operating temperatures.


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