High stereographic resolution texture and residual stress evaluation using time-of-flight neutron diffraction

徐 平光; Harjo, S.; 小島 真由美*; 伊藤 崇芳*; Gong, W.*; 鈴木 裕士; 秋田 貢一; 井上 純哉*; 友田 陽*; 相澤 一也

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The neutron diffraction technical environment for high stereographic resolution texture and residual stress combined evaluation was established at TAKUMI engineering materials diffractometer through proper neutron detector panel-region division. The pole figure evaluation of an limestone standard sample with a trigonal structure suggested that the texture measurement precision is comparable with that of the established neutron beamlines utilized for texture measurement, such as the HIPPO diffractometer at LANL and the D20 angle-dispersive neutron diffractometer at ILL. The martensite-austenite multilayered steel sheets were employed to further examine the reliability of simultaneous Rietveld analysis of the multiphase textures and the macro stress tensors. By using the BulkPathGEO micro-mechanical model, the macroscopic stress tensor analysis with a plane stress assumption confirmed a RD-TD in-plane compressive stress distribution in martensite layers and a RD-TD in-plane tensile stress distribution in austenite layers at a stress balance within 20 MPa. The phase stress partitioning at a stress level of 300 MPa was ascribed mainly to the additive effect of the volume expansion during martensite transformation and the linear contraction misfit between austenite layers and newly transformed martensite layers during the water quenching process.