Development of a Cryogenic Load Frame for In Situ Neutron Diffraction

In recent years, an increasing number of national major projects have focused on the physicochemical properties of materials and the structural integrity of components in cryogenic environments. In situ neutron non-destructive testing offers a distinct advantage for scientific research conducted under cryogenic conditions. With the progressive advancement of neutron sources and neutron diffraction techniques, neutron probes have become indispensable for the in situ observation of lattice strain, phase transformation behavior, and residual stresses in materials at cryogenic temperatures. Based on the energy-resolved neutron imaging instrument (ERNI) at Beamline 13 of the China Spallation Neutron Source (CSNS), we have developed a cryogenic loading frame for in situ neutron diffraction tensile tests. This paper presents a detailed description of the mechanical structural design, cooling and control system, strength and thermal analyses, and experimental validation of the device. The apparatus enables in situ neutron diffraction experiments over a wide temperature range of 6–473 K, with an axial loading capacity of 50 kN. Furthermore, the device was employed to conduct in situ neutron diffraction measurements on austenitic 304 stainless steel at both room and cryogenic temperatures. The experimental results confirm that this equipment exhibits stable loading capability and precise temperature control, ensuring the reliability of the experimental data.