Of all the residual stress measuring techniques, diffraction methods are widely accepted as the most general and reliable nondestructive method of quantifying the residual stress tensor. Diffraction methods use the atomic planes of the crystalline grains within the material as very sensitive strain sensors. Analysis techniques permit separation of long range macrostresses and short range or grain-to-grain microstresses.

Crystallographic texture, or the non-random orientation of grains, is also measured in the RSUC for correlation with materials performance.

The RSUC facilities include laboratory x-ray, synchrotron x-ray, and neutron diffraction instruments. Neutron diffraction is complementary to the traditional x-ray diffraction because of the great differences in a material's absorption of the two radiation types. Neutrons can penetrate many millimeters into most engineering materials, while x-rays are absorbed within a surface layer several micrometers thick. Thus, neutron diffraction can be used to probe strains throughout the volume of a material while X-rays are used to measure the strain in a shallow layer very near the surface.

 Instruments

• X-Ray Diffraction Facilities Overview
  
  • 4-Axis Goniometer/18-kW Rotating Anode X-ray Source
    
  • 4-Axis Goniometer/2-kW X-ray Tube
    
  • X14A Synchrotron 6-Axis Goniometer
    
  • Large Sample X-Ray Stress Goniometer

• Philips X'Pert Pro MPD X-Ray Diffractometer with Anton PAAR XRK-900 High Temperature Stage
  

• Neutron Diffraction Facilities Overview
  

• Neutron Powder Diffraction Micro Residual Stress Facility
  
• Neutron Diffraction Macro Residual Stress Mapping Facility
  
• Macro Residual Stress Mapping Facility Upgrades

Instruments | Applications | Recent Projects | Publications | Staff | Site Map

 User Facility Access and Proposal Form

Diffraction UC | Residual Stress UC | Thermophysical Properties UC
Diffraction & Thermophysical Prop. Group | High Temperature Materials Laboratory
Metals & Ceramics Division | Oak Ridge National Laboratory

Acknowledgments | Disclaimers

URL: http://www.html.ornl.gov/rsuc/index.html