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对比分析了两种低碳微合金钢中夹杂物对焊接热影响区组织相变的影响.对实验钢中夹杂物的分布和尺寸进行观察并在透射电镜下分析了夹杂物的选区衍射斑图样.采用热膨胀法结合金相分析建立了实验钢的连续冷却转变曲线(CCT曲线)和等温转变曲线(TTT曲线).研究发现,Ti脱氧钢中夹杂物以尺寸小于3μm的TixO--MnS型球状复合夹杂为主,其中TixO核心有两种类型(Ti2O3和Ti3O5).这类夹杂物具有诱导晶内针状铁素体形核的能力,针状铁素体优先在TixO--MnS型复合夹杂界面上形核,从而导致Ti脱氧钢相对于Al脱氧钢的贝氏体相变开始温度升高,相变时间也明显提前.
The influences of inclusions on the microstructure and phase transition in the heat-affected zone (HAZ) of two low carbon microalloyed steels were comparatively analyzed.The distribution and size of the inclusions in the experimental steel were observed and the diffraction pattern of the selected spots was analyzed under transmission electron microscope The continuous cooling transformation curve (CCT curve) and isothermal transformation curve (TTT curve) of experimental steel were established by thermal expansion method and metallographic analysis.The results show that inclusions in Ti deoxidized steel are mainly composed of TixO - MnS spherical Among them, there are two types of TixO core (Ti2O3 and Ti3O5) .These inclusions have the ability to induce intragranular acicular ferrite nucleation, and acicular ferrite is preferentially deposited at the interface of TixO - MnS type composite inclusions On the nucleation, resulting in Ti deoxidized steel relative to Al deoxidized steel bainite transformation start temperature, phase transition time is also significantly advanced.