Determining Individual Phase Flow Properties in a Quench and Partitioning Steel with In Situ High-Energy X-Ray Diffraction and Multiphase Elasto-Plastic Self-Consistent Method

Journal Article · Fri Feb 26 04:00:00 EST 2016 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-016-3373-2· OSTI ID:1333996

Hu, Xiaohua; Choi, Kyoo Sil; Sun, Xin; Ren, Yang; Wang, Yangdong

The micromechanical properties of the constituent phases were characterized for an advanced high strength steels (AHSS) produced by a quenching and partitioning (Q&P) process with in-situ tensile loading under Synchrotron-based high energy X-ray diffraction. The constituent phases present are retained austenite and three martensites (tempered, untempered and freshly formed martensites). For the material investigated, the 200 and 220 lattice strains of the retained austenite phase were calculated by examining the changes of the X-ray diffraction peak positions during deformation. The 200 and 211 lattice strains of the various martensitic phases with similar crystal structures were determined by separating their overlapped diffraction peaks. Apart from tempered and untempered martensite, the diffraction peaks of freshly formed martensite as a result of austenite to martensite transformation can also be able separated due to high initial austenite volume fraction. The phase stresses are first estimated with an empirical relationship through the X-ray diffraction elastic constants (XREC). A multi-phase elasto-plastic self constant model (EPSC) is next used for more accurate determination of the constitutive behaviors of the various phases by comparing the predicted lattice strain distributions and global stress-strain curves with the measured ones. The determined constitutive laws will be used for microstructure-based modeling for sheet formability of the Q&P AHSS steel.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1333996
• Report Number(s): PNNL-SA-106037; VT0505000
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 47; ISSN 1073-5623
• Publisher: ASM International
• Country of Publication: United States
• Language: English