摘要
采用0.07 wt%Ti和0.015 wt%Nb-0.07 wt%Ti微合金化的成分体系,通过控轧控冷和控轧控冷+回火工艺制备了厚度为30 mm的钢板。钢板在TMCP状态的形貌为贝氏体板条和沿贝氏体板条分布的马奥组元和析出物构成。回火后马奥组元分解,贝氏体板条界面弱化,在贝氏体板条中形成了大量细小的Ti的析出物。钢板中的析出物主要包括:粗大的TiN析出、TiC、Ti4 C2 S2析出和Nb-Ti的复合析出等。粗大方形TiN在钢中的Al2 O3、MgO或Ti2 O3的夹杂上形核长大,边长为5μm左右。在0.07 wt%Ti成分体系中,TMCP和TMCP+回火状态钢板中的析出物主要是100 nm以下的TiN、TiC和Ti4 C2 S2析出。在0.015wt%Nb-0.07 wt%Ti成分体系中,析出物主要是Ti和Nb的碳化物析出,尺寸300 nm以下。添加微量的Nb会导致0.07 wt%Ti钢板的强度和冲击功下降,其原因可能是由于Nb和Ti形成较大的复合析出物,降低了析出物对位错运动的抑制作用,导致钢板力学性能下降。
Two kinds of heavy steel plates with 0.07 wt% Ti and 0.015 wt% Nb-0.07 wt% Ti were produced by TMCP and TMCP plus tempering process.Microstructure of the steel plate is composed of bainitic ferrite laths and martensite-austenite（MA） distributed along boundary of the laths.MA decomposes and fine precipitates are found in the steel plates after tempering.The precipitates include coarse TiN,TiC and Ti4 C2 S2 and complex Nb-Ti carbides.TiN nucleates and grows at inclusions of Al2 O3,MgO and Ti2 O3.TiC and Ti4 C2 S2 precipitates with radius less than 100 nm were detected in 0.07 wt% Ti steel,therefore,complex carbides precipitates of Nb-Ti with radius below 300 nm are observed in 0.015 wt% Nb-0.07 wt% Ti steel.Nb addition in 0.07 wt% Ti steel decreases its strength and impact energy at low temperature,and it is suggested that the decrease of mechanical properties is due to decreasing of the effect of coarse complex Nb-Ti precipitates on dislocation mobility.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2010年第12期71-79,共9页
Transactions of Materials and Heat Treatment
关键词
贝氏体
TI微合金化
析出
力学性能
厚钢板
bainite
Ti microalloyed
precipitation
mechanical property
heavy steel plate
