Revealing the cyclic hardening mechanism of an austenitic stainless steel by real-time in situ neutron diffraction

2014 ◽  
Vol 89 ◽  
pp. 45-48 ◽  
Author(s):  
D. Yu ◽  
K. An ◽  
Y. Chen ◽  
X. Chen
JOM ◽  
2018 ◽  
Vol 70 (8) ◽  
pp. 1576-1586 ◽  
Author(s):  
Dunji Yu ◽  
Lu Huang ◽  
Yan Chen ◽  
Piyamanee Komolwit ◽  
Ke An

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 360 ◽  
Author(s):  
Dunji Yu ◽  
Yan Chen ◽  
Lu Huang ◽  
Ke An

Real-time in situ neutron diffraction was used to characterize the crystal structure evolution in a transformation-induced plasticity (TRIP) sheet steel during annealing up to 1000 °C and then cooling to 60 °C. Based on the results of full-pattern Rietveld refinement, critical temperature regions were determined in which the transformations of retained austenite to ferrite and ferrite to high-temperature austenite during heating and the transformation of austenite to ferrite during cooling occurred, respectively. The phase-specific lattice variation with temperature was further analyzed to comprehensively understand the role of carbon diffusion in accordance with phase transformation, which also shed light on the determination of internal stress in retained austenite. These results prove the technique of real-time in situ neutron diffraction as a powerful tool for heat treatment design of novel metallic materials.


2006 ◽  
Vol 524-525 ◽  
pp. 917-922 ◽  
Author(s):  
Ru Lin Peng ◽  
Yan Dong Wang ◽  
Guo Cai Chai ◽  
Nan Jia ◽  
Sten Johansson ◽  
...  

Microstresses due to intergranular and inter-phase interactions in an austenitic-ferritic super duplex steel (SAF 2507) under uniaxial compressive deformation have been studied by in-situ neutron diffraction experiments. Lattice strains of several hkl planes of austenite respective ferrite were mapped as a function of sample direction at a number of load levels during loading into the plastic regime and unloading. The analysis of the experimental results has shown that during loading both grain-orientation-dependent and inter-phase stresses were generated under plastic deformation that was inhomogeneous at the microstructural level. Residual stresses depending on the grain-orientation and phase have been found after unloading. The results also indicate stronger intergranular interactions among the studied hkl planes of austenite than those of ferrite.


2012 ◽  
Vol 706-709 ◽  
pp. 1737-1742 ◽  
Author(s):  
D.J. Goossens ◽  
R.E. Whitfield ◽  
A.J. Studer

The phase evolution during the sintering of metal injection moulded stainless steel, 316Land 17-4PH, has been observed using in situ neutron diffraction and Rietveld analysis. The formationof the ferrite phase in the final product is associated with the production of -ferrite at high temperatures.Coexistence of phases at high temperature is thought to allow the segregation of alloyingelements, stabilising the ferrite to lower temperature. To prevent ferrite in the final products the sinteringmust occur at a lower temperature than that at which -ferrite is formed. An alternative regimeis proposed in which the temperature would be cycled around the formation temperature of -ferrite.


2004 ◽  
Vol 840 ◽  
Author(s):  
Kaixiang Tao ◽  
James J. Wall ◽  
Donald W. Brown ◽  
Hongqi Li ◽  
Sven C. Vogel ◽  
...  

ABSTRACTIn-situ, time-of-flight neutron diffraction was performed to investigate the martensitic phase transformation during quasi-static uniaxial compression testing of 304L stainless steel at 300K (room temperature) and 203K. In-situ neutron diffraction study enabled the bulk measurement of intensity evolution for each hkl atomic plane during the austenite (fcc) to martensite (hcp and bcc) phase transformation. The neutron diffraction patterns show that the martensite phases started to develop at about 2.5% applied strain (600 MPa applied stress) at 203K. However, at 300K, the martensite formation was not observed throughout the test. Furthermore, from changes in the relative intensities of individual hkl atomic planes, the selective phase transformation can be well understood and the grain orientation relationship between the austenite and newly-forming martensite phases can be determined. The results show that the fcc grain families with {111} and {200} plane normals parallel to the loading axis are favored for the “fcc to hcp” and “fcc to bcc” transformations, respectively.


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