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研究了钒微合金化对高强双相钢微观组织及性能的影响。与Fe-0.186C-1.5Mn-0.3Si-0.008N参照钢相比,加入0.14%V带来如下效果:(1)在冷轧及退火状态铁素体晶粒高度细化;(2)严重推迟在连续退火过程中铁素体向奥氏体转变的初始动力学;(3)慢冷条件下铁素体开始转变温度稍微提高,但珠光体和贝氏体转变被抑制,导致淬透性提高;(4)在临界退火温度≤740℃时观察到未溶渗碳体;(5)750℃/180 s退火后铁素体相中发现大量V(C,N)析出(平均直径7.4 nm),而马氏体(奥氏体)中析出物稀少,尺寸更大(平均直径13.4 nm);(6)不含钒参照钢抗拉强度随马氏体体积分数增量为~16 MPa/%,而含钒钢由于晶粒细化和铁素体选择强化,强度随马氏体含量变化增量相当低(~4 MPa/%),在马氏体体积分数>45%变软。
The effect of vanadium microalloying on the microstructure and properties of high strength dual phase steel was studied. Compared with the Fe-0.186C-1.5Mn-0.3Si-0.008N reference steel, the addition of 0.14% V brings about the following effects: (1) the ferrite grains are highly refined in cold rolling and annealing conditions; (2) severe Postponing the initial kinetics of ferrite transformation to austenite during continuous annealing; (3) the onset temperature of ferrite transformation slightly increases under slow cooling, but the pearlite and bainite transformation are inhibited, resulting in an increase in hardenability ; (4) Undissolved cementite was observed at the critical annealing temperature of ≤740 ℃; (5) A large amount of V (C, N) was found in the ferrite phase after annealing at 750 ℃ for 180 s (average diameter 7.4 nm) , Whereas the precipitates in martensite (austenite) are sparse and larger in size (average diameter 13.4 nm). (6) The tensile strength of vanadium-free reference steel increases with the increment of martensite volume fraction to 16 MPa / , Whereas for vanadium-bearing steels, the increase in strength with martensite content is relatively low (~ 4 MPa /%) due to grain refinement and ferrite-selective strengthening and softens with martensite volume fraction> 45%.