| Title |
Microstructure and Mechanical Properties of HSLA Steel of Different Starting Structures by Intercritical Annealing |
| Authors |
맹선재(Sun Chae Maeng); 장동현(Dong Hyean Jang); 조현권(Hyun Kwen Cho); 신동혁(Dong Hyuk Shin) |
| Abstract |
Austenite formation and mechanical properties of HSLA steel of different starting structures has been studied by intercritical annealing(IA). The different starting structures are: ferrite＋pearlite (FP1), martensite(M1), cold worked ferrite＋pearlite(FP2) and cold worked martensite(M2). Austenite was nucleated at ferrite grain boundaries in FP1 and FP2 and also at the interior of the grains in case of FP2. By increasing the IA time globular austenite structures were distributed uniformly all over the space enclosing the ferrite phase. Austenite in M1 and M2 was nucleated at the interface between prior martensite laths and the globular strutctures were formed from the former acicular structures. By increasing the IA time M2 has shown well developed globular austenite structure than M1 and the agglomerated continuous austenite networks surrounding ferrite phases were formed. Tensile strength in all the tested samples of different starting structures was increased by increasing the IA time. Any noticeable change in elongation was not found in FP1, FP2 and M2 by the increase of IA time. Exceptionally elongation of M1 was increased by increased IA time. Chapy V-notch impact values of all the different starting sturctures were decreased by increasing the IA time. |