CSP工艺钛微合金碳钢中的碳氮化钛析出相

 应用透射电镜、高分辨电镜等方法观察分析了薄板坯连铸连轧EAF-CSP工艺生产的微钛低碳钢热轧板的含钛析出相，实验钢的成分为(mass%）：C：0.04~0.07%、Si：0.6%、Mn：0.6%、Ti：0.06~0.14 %。电解萃取及X射线衍射分析结果表明：钢中存在不同碳氮比的碳氮化钛析出相，这些碳氮化物的C/N比值的差异是由各个析出相的形成温度及析出时钛和氮、碳元素在钢中的过饱和度不同而造成的。实验钢萃取粉末（包括各种析出相）的质量分数约占钢的0.305%。其中五分之四左右为渗碳体，另外五分之一主要是钛的碳化物、氮化物和碳氮化物，还有少量的硫化物和氧化物。在薄板坯连铸连轧工艺的连铸坯及热轧板中均观察到了由相间沉淀方式形成的碳氮化物粒子列。本文讨论了相间沉淀的形成机制。与传统连铸连轧工艺生产的同类钢相比，CSP工艺低碳钢中微量钛的加入明显增加了细小析出相的数量。

Carbonitride Precipitates in Strips With Ti Additive Produced by CSP Process

Hot strips of low carbon steels with Ti additive (containing 0.04~0.07%C, 0.6% Si, 0.6% Mn, 0.06~0.14 %(mass) Ti) produced by EAF-CSP (Electric Arc Furnaces -Compact Strip Production) process have been examined by TEM, HREM and XRD. Titanium carbonitrides with different C/N ratio were found in the samples. The varying composition of the Ti-carbonitrides is resulted from the supersaturation of Ti, N and C in the steel and the temperature at which the compound form. It is pointed out by XRD analysis that the mass fraction of the extracted powder is about 0.305% of the specimen in total. Among them about four fifths are cementite, the remains are mainly titanium carbonitrides, carbides, nitrides, sulfide and oxides.Particle arrays formed through the interphase precipitation are observed either in the slabs or in the hot strips. The dominating reaction mechanism is discussed. Compared with the conventional cold charge process, small addition of Ti would be more effective for precipitation of fine precipitates in the steels produced by CSP process.