钛处理对EH36船板钢中夹杂物及组织特征影响

 为了研究结晶器喂钛线对EH36船板钢中夹杂物的影响,采用无水有机溶液电解分离提取钢中夹杂物,结合扫描电镜和能谱仪分析其三维形貌,尺寸和成分。试验结果表明,在结晶器喂钛线后,钢中硅铝酸钙夹杂物+外包裹MnS转变为硅铝酸钙钛+MnS夹杂物,三维表面从光滑转变为粗糙多孔的形貌。在焊接热模拟后的试样中,组织形貌从未加钛试样中的晶界铁素体和侧板条铁素体转变为钛处理试样中的针状铁素体,且夹杂物周围铁素体从块状转变为针状,韧性提高了70 J。通过热力学理论计算,分析船板钢中含钛氧化物夹杂物形成条件。计算结果表明,钛、铝与氧反应生成氧化物的过程存在竞争关系,当钢中钛质量分数为0.02%时,钢液中应严格控制铝质量分数不高于0.003 5%,才能保证钢液中大量生成含钛氧化物粒子。

Effect of titanium treatment on inclusions and microstructure in EH36 shipbuilding steel

In order to study the influence of titanium treatment (the mold feeding titanium wire) on inclusions in EH36 steel,the size,composition and three-dimensional morphologies of inclusions in EH36 shipbuilding steel were obtained by electrolytic extraction method using non-aqueous electrolytes combined with SEM method. The experimental results show that the Ca-Si-Al system oxide inclusion+MnS in the steel was transformed into Ca-Si-Al-Ti system oxide inclusion+MnS after feeding the titanium wire in the mold,and the three-dimensional surfaces of them changes from smoother to rough and porous. After the welding thermal simulation,the microstructure had transformed from the grain boundary ferrite and side slatted ferrite in a titanium-free sample into acicular ferrite in the containing titanium specimen. What is more,the morphology of ferrite around the inclusion was transformed from block into acicular,the toughness was increased by 70 J. The forming conditions of titanium oxide inclusions in shipbuilding steel were analyzed by the thermodynamic calculation. The calculation results show that there was a competitive relationship between titanium and aluminum which react with oxygen to form oxide. The mass percent of aluminum should be strictly controlled not more than 0.003 5% in liquid steel when the mass percent of Ti was 0.02% in steel. Thus,so as to ensure that a substantial amount of titanium-containing oxide particles could be generated in liquid steel.