Development of high strength ductile hypereutectoid steel by cyclic heat treatment process

被引:44
作者
Saha, Atanu [2 ,3 ]
Mondal, Dipak Kumar [1 ]
Biswas, Koushik [4 ]
Maity, Joydeep [1 ]
机构
[1] Natl Inst Technol Durgapur, Dept Met & Mat Engn, Durgapur 713209, W Bengal, India
[2] CSIR Cent Mech Engn Res Inst, NDT, Durgapur 713209, W Bengal, India
[3] CSIR Cent Mech Engn Res Inst, Met Grp, Durgapur 713209, W Bengal, India
[4] Indian Inst Technol, Dept Met & Mat Engn, Kharagpur 721302, W Bengal, India
来源
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 2012年 / 541卷
关键词
Hypereutectoid steel; Cyclic heat treatment; Lamellar faults; Fragmentation and thickening of cementite lamella; Divorced eutectoidal reaction; Cementite plates and spheroids; Strength and ductility; DISLOCATION INTERPHASE BOUNDARIES; TRANSFORMATION TEMPERATURE; MECHANICAL-PROPERTIES; PEARLITIC STEELS; CARBON-STEELS; KINK MOTION; MICROSTRUCTURE; SPHEROIDIZATION; MIGRATION; AUSTENITE;
D O I
10.1016/j.msea.2012.02.026
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
In this work a homogenizing annealed 1.24 wt% carbon steel was subjected to cyclic heat treatment process that consisted of repeated short-duration (6 min) holding at 894 degrees C (above Acm temperature) followed by forced air cooling. During short-duration holding at 894 degrees C. fragmentation (owing to partial dissolution) and thickening of cementite lamella occurred at the preferred high energy sites of lamellar faults. These undissolved fragmented cementite acted as pre-existing nuclei promoting the divorced eutectoidal reaction (DET) during forced air cooling that generated non lamellar region (NLR) in the microstructure apart from the presence of lamellar pearlite region (LPR) and cementite network (CN). The CN was also fragmented with repeated holding and cooling cycles. Besides, new lamellar fault sites were generated during forced air cooling to promote lamellar fragmentation. Accordingly, as the number of heat treatment cycles increases, more uniformly dispersed finer cementite particles (pre-existing nuclei) in austenite matrix was obtained at 894 degrees C. Therefore, the proportion of NLR increased and the proportions of LPR and CN decreased with the progress of cyclic heat treatment. After 8 cycles of heat treatment the microstructure mostly consisted of a combination of spheroids (0.55 +/- 0.24 mu m in size) and non-spheroids (mainly the plate shaped particles of 0.22 +/- 0.10 mu m in size) of cementite in 1:5 proportion by area% dispersed in ferrite matrix. The generation of cementite plates occurred through the motion of transformation disconnections. This provided an excellent combination of strength (UTS = 1086 MPa) and ductility (%elongation = 13) in this 1.24 wt% C steel. The property obtained had similarity to what was reported for a thermo-mechanically processed steel of much higher carbon content (1.8 wt%) where the microstructure consisted of solely the cementite spheroids of 0.65 mu m average size dispersed in ferrite matrix. (C) 2012 Elsevier B.V. All rights reserved.
引用
收藏
页码:204 / 215
页数:12
相关论文
共 33 条
[1]   On the mechanism of formation of diffusional plate-shaped transformation products [J].
Aaronson, HI ;
Furuhara, T ;
Hall, MG ;
Hirth, JP ;
Nie, JF ;
Purdy, GR ;
Reynolds, WT .
ACTA MATERIALIA, 2006, 54 (05) :1227-1232
[2]   DIFFUSIONAL AND DISPLACIVE TRANSFORMATIONS [J].
BHADESHIA, HKDH .
SCRIPTA METALLURGICA, 1987, 21 (08) :1017-1022
[3]   THE GROWTH OF CRYSTALS AND THE EQUILIBRIUM STRUCTURE OF THEIR SURFACES [J].
BURTON, WK ;
CABRERA, N ;
FRANK, FC .
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES, 1951, 243 (866) :299-358
[4]   ACCELERATED SPHEROIDIZATION OF HYPOEUTECTOID STEEL BY THE DECOMPOSITION OF SUPERCOOLED AUSTENITE [J].
CHOU, CC ;
KAO, PW ;
CHENG, GH .
JOURNAL OF MATERIALS SCIENCE, 1986, 21 (09) :3339-3344
[5]  
Dieter G. E., 1988, MECH METALLURGY, P217
[6]   Continuous cooling transformation temperature and microstructures of microalloyed hypereutectoid steels [J].
Elwazri, A. M. ;
Wanjara, P. ;
Yue, S. .
ISIJ INTERNATIONAL, 2006, 46 (09) :1354-1360
[7]   Effect of prior-austenite grain size and transformation temperature on nodule size of microalloyed hypereutectoid steels [J].
Elwazri, AM ;
Wanjara, P ;
Yue, S .
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 2005, 36A (09) :2297-2305
[8]   The kinetics of static recrystallization in microalloyed hypereutectoid steels [J].
Elwazri, AM ;
Essadiqi, E ;
Yue, S .
ISIJ INTERNATIONAL, 2004, 44 (01) :162-170
[9]   Computer simulation of ledge migration under elastic interaction [J].
Enomoto, M ;
Hirth, JP .
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 1996, 27 (06) :1491-1500
[10]   Precipitation of paraequilibrium cementite: Experiments, and thermodynamic and kinetic modeling [J].
Ghosh, G ;
Olson, GB .
ACTA MATERIALIA, 2002, 50 (08) :2099-2119