2017 Fiscal Year Research-status Report
Hydrogen embrittlement-resistant upgradation and its mechanism of ultrahigh strength steel through texture control
| Project/Area Number |
17K06852
|
|---|
| Research Institution | Japan Atomic Energy Agency |
|---|
Principal Investigator |
徐 平光 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 物質科学研究センター, 研究副主幹 (80554667)
|
|---|
| Project Period (FY) |
2017-04-01 – 2020-03-31
|
| Keywords | Texture analysis / Tensile deformation / High strength steel / Hydrogen charging / Neutron diffraction |
|---|
| Outline of Annual Research Achievements |
Neutron diffraction is a powerful tool to evaluate the tensile deformation through the relative change of lattice plane spacing, i.e. elastic strain and through the relative grain rotation and crystal shear slip, i.e. deformation texture. Given the wide beam size and weak beam flux of neutron diffraction, it is difficult to evaluate the hydrogen charged tensile deformation of a steel sample because the gradual distribution of diffusional hydrogen in steel and its continuous loss from steel surface if without some surface protection layer. We attempted a surface zinc plating method after charging to prevent the hydrogen loss, and we used a long-time room-temperature holding to promote the macroscopic uniform distribution of diffusional hydrogen in steel samples. As a result, the neutron diffraction became possible to monitor the tensile deformation behavior of hydrogen charged high strength steel samples.
Moreover, we proposed and confirmed that high stereographic resolution through finely dividing neutron detector regions for collecting each neutron diffraction pattern during time-of-flight neutron diffraction is effective to improve the reliability of combined texture and macro stress tensor analysis. Such high stereographic resolution neutron diffraction is much important to evaluate the anisotropic tensile deformation behavior of hydrogen charged high strength steel plates with certain preferred orientation.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
In this budget year, the cylinder tensile samples were prepared from commercial high strength steel plates, and the electrochemical hydrogen charging process and the zinc plating process were optimized to get a smooth and dense surface layer for preventing the diffusional hydrogen loss.
The microstructure observation confirmed that the high strength steel plates were with crystallographic preferred orientation even after the commercial quenching and tempering treatment, and the tensile deformation tests confirmed the existence of plastic anisotropy.
The neutron diffraction experimental proposal was approved for the anisotropic tensile deformation of high strength steel samples without hydrogen charging, with low and high diffusional hydrogen charging. The macroscopic tensile deformation behaviors during neutron diffraction were almost consistent with our expectation.
|
| Strategy for Future Research Activity |
The neutron diffraction patterns obtained during the in situ tensile deformation are being urgently analyzed, and some additional neutron diffraction experiments will be carried out for the above tensile deformation.
The fracture morphology observation, the cracks initiation and propagation observation and the diffusional hydrogen content analysis are necessary to be carried out before conference presentation and journal paper preparation.
The strain/stress and bulk texture of various hydrogen charged steel samples after anisotropic tensile deformation need to be measured and analyzed.
The up-to-date research progress information or literature about hydrogen embrittlement and its prevent technology will be collected widely even through attending some related international and domestic academic conferences.
The effect of hydrogen charging on anisotropic tensile deformation of high steel plate will be investigated and the possibility of texture control for improving hydrogen embrittlement resistance will be discussed, then a new high strength steel plate or sheet will be prepared in trial based on the above study.
|
| Causes of Carryover |
The hydrogen charging and surface plating experiments, previously planned to carry out in some company, are carried out in our research institute through the cooperative research activity between different research groups. So that, the related budget will be re-arranged for preparing the new high strength steel plate in trial.
|
-
[Journal Article] High stereographic resolution texture and residual stress evaluation using time-of-flight neutron diffraction2018
Author(s)
Xu, P.G., Harjo, S., Ojima, M., Suzuki, H., Ito, T., Gong, W., Vogel, S.C., Inoue, J., Tomota, Y., Aizawa, K.
-
Journal Title
Journal of applied crystallography
Volume: 51
Pages: 印刷中
DOI
Peer Reviewed / Open Access / Int'l Joint Research
-
-
-
-
