کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7972131 | 1514616 | 2018 | 25 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Microstructure-property relationship in a low carbon Nb-B bearing ultra-high strength steel by direct-quenching and tempering
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
دانش مواد (عمومی)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
This work describes here the synergistic effect of niobium micro-alloying in combination with boron addition on the development of a 900â¯MPa grade ultra-high strength low carbon cost-effective bainitic steel processed by direct-quenching and induction tempering. A mixed microstructure consisting of acicular ferrite and lath bainite associated with high density of high angle grain boundaries was obtained by controlled rolling and direct-quenching. Nano-sized precipitation behavior during controlled rolling and induction tempering was studied by transmission electron microscopy (TEM). A number of nano-sized precipitates were observed in the matrix after controlled rolling and direct-quenching. These precipitates were identified by electron energy loss spectrometry (EELS) in scanning TEM (STEM) to be TiN-Nb(C,N) or TiN-NbC composite precipitates, and were associated with mean austenite grain size of ~ 34â¯Â±â¯6â¯Âµm in steel before finishing rolling. A finish rolling reduction of 67% below non-austenite recrystallization temperature pancaked the austenite grains to 10-15â¯Âµm in thickness. Nano-sized NbC formed during induction tempering at 670â¯Â°C had an average diameter of ~ 4.3â¯nm and 9.5â¯nm for tempering duration of 5â¯min and 30â¯min, respectively. It is noted that while nano-sized NbC precipitates smaller than 5â¯nm provide significant precipitation hardening effect to increase the mechanical strength, acicular ferrite in the mixed microstructure helps in retaining high elongation of low carbon direct-quenched and tempered steel. Ultra-high yield strength of 944â¯MPa with high ductility (uniform elongation of 6.3% and total elongation of 20%) was obtained after induction tempering at 670â¯Â°C for 5â¯min.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volume 727, 6 June 2018, Pages 200-207
Journal: Materials Science and Engineering: A - Volume 727, 6 June 2018, Pages 200-207
نویسندگان
Z.J. Xie, C.J. Shang, X.L. Wang, X.P. Ma, S.V. Subramanian, R.D.K. Misra,