Fraunhofer Institute for Mechanics of Materials IWM
Fraunhofer Institute for Mechanics of Materials IWM

Microstructure and Residual Stresses

Tailored material microstructures lead to innovative materials functions and reliable components.

 

A material’s microstructure determines its mechanical, thermal, electrical, and optical properties. Its susceptibility to chemical reactions, such as corrosion or oxidation, is also influenced by the microstructure. It determines how high-performance and durable the products are. By elucidating the relationships between process, microstructure, and properties, we lay the foundation for targeted materials selection, the optimization of materials and the process chain, and the prediction of operational behavior. We investigate the influence of manufacturing processes and operational stresses on the microstructure and the residual stress state of materials and components.

We establish the connection between the desired function of materials and components and the required process control. We clarify how the microstructure develops during operation and in manufacturing processes and how microstructure development can be specifically influenced. We help you create innovative products and reliable components with customized materials.

We can assist you in these fields of application

 

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Quality Assurance in Materials Processing

Deviations or irregularities in raw materials, starting materials, or semi-finished products — such as defects, contamination, fluctuating properties, or residual stresses — cannot be completely ruled out. Strategies are needed to identify, evaluate, and ultimately address these issues, as they have a direct impact on the final microstructure during processing and, consequently, on the quality of the end products.

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Predictable Thermal Processes

To achieve the desired mechanical, chemical, and physical properties of components in thermal processes such as welding, casting, hardening, sintering, or laser melting, a thorough understanding of the relationship between temperature history and properties is required. Phase transformations play a particularly important role in this context.

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Substitution of critical raw materials

Regulatory requirements, limited availability, changing operating conditions, and new customer demands often necessitate the substitution of critical raw materials or the development of new materials properties in many applications. Only with the appropriate knowledge base regarding materials properties and behavior can the necessary technological decisions be made to develop new materials solutions while meeting economic and environmental constraints.

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Damage Investigation and Prevention

When component damage occurs, it is generally the result of a combination of the materials, the process chain, and operating conditions. To conduct a thorough investigation of the causes, mechanical, thermal, corrosive, and tribological factors, as well as the effects of the operating medium and their interactions, must be analyzed. To prevent damage in the long term, manufacturing defects must be eliminated, materials irregularities must be controlled, and, if necessary, the component design must be modified.

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We make materials predictable.

Analysis and Simulation of Microstructure Formation

 

We identify the relationships between microstructure and materials properties and use this information to develop optimized materials properties and ensure safe materials use. Through simulations, we can predict microstructures and evaluate them in terms of component reliability, safety, and service life.

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Analysis and Simulation of Residual Stresses

 

We identify residual stresses caused by manufacturing and service conditions and develop recommendations for component design, materials selection, and manufacturing processes. For our clients, we implement a cost-effective measurement strategy tailored to their specific needs and ensure an economical and reliable assessment of residual stress conditions.

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Crystal Structure and Phase Analyses

 

We correlate mechanical, electrical, and magnetic properties with crystal and microstructure, and explain changes in properties resulting from high-temperature use, deformation, and corrosion. To do this, we use X-ray, synchrotron, and neutron radiation to generate diffraction patterns that provide information about the atomic arrangement in a polycrystalline component. In the laboratory, we can also simulate conditions that occur during the actual operation of the materials and components.

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Failure Analysis and Investigation of Damage Mechanisms

 

We identify the causes of failure and define measures to prevent technical failures in the long term. In our failure analyses, we examine the entire context on a case-by-case basis, including the materials, the process chain, and the operating conditions. We analyze mechanical, thermal, corrosive, and tribological factors, as well as the behavior of materials and components in the presence of media.

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Development and Manufacture of Porous Functional Materials

 

We develop capillary suspensions (CapS) with customized properties tailored to specific requirements (porosity and strength). This enables us to create pore and materials gradients as well as complex geometries that optimize mass transport and increase the efficiency of energy conversion. For industrial applications, we offer technology transfer and the scaling of CapS technology.

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We make materials predictable.

  • In small and large projects with companies from various industrial sectors, we answer the questions: WHAT is happening inside materials? WHY is it happening? HOW can it be influenced? Our expertise helps you make well-informed decisions and gain a competitive edge.
  • Our focus is on the microstructure of materials. It determines the function, behavior, and service life of components. Using our highly specialized methods for characterizing microstructures and measuring residual stresses (e.g., via X-ray, synchrotron radiation, and neutron diffraction), we can evaluate the mechanisms underlying their formation and changes and derive recommendations for optimization.
  • Manufacturing processes such as welding, machining, heat treatment, and additive manufacturing generate residual stresses and microstructural changes. We help to specifically adjust or minimize these in order to increase component quality and service life.
  • In our projects, we address challenges from the automotive, energy, aerospace, and mechanical engineering industries and can transfer our methods and findings across sectors.

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Publications on Microstructure and Residual Stresses

 

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Articles in journals, books, and conference proceedings, as well as dissertations and project reports...

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