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Determining the Mechanical Strength of Ultra-Fine-Grained Metals
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Dislocation-twin boundary interactions induced nanocrystalline via SPD processing in bulk metals.
Fucheng Zhang1, Xiaoyong Feng1, Zhinan Yang1
1State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
Scientific Reports
|March 12, 2015
Summary
Dislocations interacting with twin boundaries (TBs) in Hadfield steel can cause TBs to transform into high-angle grain boundaries (GBs). This microstructural evolution is driven by dislocation reactions and accumulation at the TB during severe plastic deformation.
Area of Science:
- Materials Science
- Metallurgy
- Solid Mechanics
Background:
- Hadfield steel is known for its excellent toughness and work hardening capabilities.
- Understanding microstructural evolution under severe plastic deformation is crucial for optimizing material properties.
- Dislocation-twin boundary interactions play a significant role in the mechanical behavior of crystalline materials.
Purpose of the Study:
- To investigate the mechanisms by which dislocation-twin boundary (TB) interactions lead to the disappearance of TBs.
- To analyze the microstructural evolution of Hadfield steel subjected to severe plastic deformation.
- To develop a physical model explaining dislocation reactions at TBs and their role in transitioning coherent TBs to incoherent high-angle grain boundaries (GBs).
Main Methods:
- Observation of microstructural evolution in Hadfield steel over varying severe plastic deformation times.
- Analysis of dislocation structures and reactions occurring at twin boundaries.
- Development of a physical model based on dislocation theory to explain observed phenomena.
Main Results:
- Severe plastic deformation processing leads to the formation of sessile Frank partial dislocations and/or sessile unit dislocations on the TB.
- Dislocation reactions at the TB create atomic steps and facilitate the accumulation of gliding dislocations.
- These processes result in the transformation of coherent TBs into incoherent GBs.
Conclusions:
- Dislocation accumulation and reactions at twin boundaries are the primary drivers for the transition from TBs to GBs in Hadfield steel under severe plastic deformation.
- The established physical model provides a detailed explanation for the observed dislocation reactions and microstructural changes.
- Understanding these interactions is key to controlling the microstructure and properties of Hadfield steel during processing.
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