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研究了一种微合金钢中夹杂物与模拟焊接热影响区微观组织以及低温冲击韧性的关系.结果发现:实验钢夹杂物以类球状Ti2O3-Al2O3-MnS型复合夹杂为主,分布较为均匀且尺寸小于3μm;在相变冷却时间较短(T8/5=40s)时,试样微观组织以针状铁素体和沿晶铁素体为主,板条贝氏体束较少,原奥氏体晶粒尺寸在50μm左右,低温冲击性能优良;随着相变冷却时间的延长(T8/5=60,80s),原奥氏体晶粒尺寸也随之增大,相变温度的提高和相变区域的变宽使得位于原奥氏体晶界附近的夹杂物对晶界处多边形铁素体的诱导促进作用更加明显,沿晶铁素体长大剧烈,一定程度上消耗了晶内针状铁素体对组织的分割细化作用,使得低温冲击韧性有所降低.
The microstructure and the low temperature impact toughness of inclusions in a microalloyed steel were studied.The results show that inclusions in the experimental steel are dominated by spheroidal Ti2O3-Al2O3-MnS composite inclusions, Size less than 3μm. When the cooling time of phase transformation is short (T8 / 5 = 40s), the microstructure of the sample is mainly acicular ferrite and intergranular ferrite, with less lath bainite. With the grain size of about 50μm, the low temperature impact performance is good. With the extension of the cooling time (T8 / 5 = 60,80s), the original austenite grain size increases and the transformation temperature increases And the broadening of the phase change region makes the inclusions located near the original austenite grain boundary more obviously promote the polygonal ferrite at grain boundaries. The growth of the intergranular ferrite is fierce and consumes a certain amount of intragranular Acicular ferrite on the organization of thinning effect, making low temperature impact toughness decreased.