酸洗弹簧钢冷轧掉粉原因分析  

Cause analysis of the surface powder loss of pickling spring steel during cold rolling

作　　者：李雯 裴新华 赵楠 LI Wen;PEI Xinhua;ZHAO Nan(R&D Center,Meisteel of Baosteel Research Institution,Nanjing 210039,China)

机构地区：[1]宝钢研究院梅钢技术中心,江苏南京210039

出　　处：《轧钢》2024年第4期128-133,共6页Steel Rolling

摘　　要：针对弹簧钢60Si2Mn带钢酸洗退火后冷轧时发生表面掉粉的问题,对退火、冷轧试样的表面、截面形貌及化学成分进行了分析,发现退火、冷轧试样表面存在约10μm厚、以Fe为主要成分的明显疏松层,轧制脱落的粉状物质主要为Fe。为进一步探明疏松层与氧化铁皮的相关性,在实验室制备了热轧试样、不完全酸洗试样、完全酸洗试样进行全氢罩式退火,结果显示:热轧试样经退火后,表面氧化铁皮被完全还原为一层致密金属铁,不完全酸洗试样表面出现类似轧制掉粉的疏松层结构,完全酸洗试样表面仍保留酸洗初始表面。此外,60Si2Mn热轧试样厚度6μm的氧化铁皮下存在厚度8μm的内氧化层,不完全酸洗试样退火后,表面疏松层厚度为8μm,远大于热轧试样氧化铁皮厚度,且明显向基体扩展。实验研究发现:60Si2Mn带钢表面氧化铁皮结构致密,其酸洗主要以微裂纹形式腐蚀去除氧化铁皮,由于所需酸洗时间约为常规高碳钢的数倍,因此在去除表面氧化铁皮的同时,内氧化层发生明显的晶间腐蚀,与残留的氧化铁皮一起在退火后形成疏松结构而导致冷轧掉粉问题。因此,对于60Si2Mn带钢,一方面要尽量酸洗彻底无氧化铁皮残留,另一方面需控制内氧化层厚度,避免酸洗时内氧化层发生沿晶腐蚀而产生表面疏松的风险。Aiming at the surface powder loss of pickling spring steel 60Si2Mn during cold rolling after annealing,the surface,cross-sectional morphology and composition of annealed and cold rolled samples were analyzed,and it was found that there was an obvious loose layer of about 10μm on the surface of the annealed and cold rolled samples,with Fe as the main component,and the powdery substance that was rolled off was mainly Fe too.In order to further explore the correlation between the loose layer and the iron oxide scale,the hot rolled sample,incomplete pickling sample and complete pickling sample were annealed in the full hydrogen furnace,and the results showed that the surface iron oxide scale of hot rolled sample was completely reduced to a layer of dense metal iron,and the loose layer structure similar to rolling powder appeared on the surface of the incomplete pickling sample,and the surface of the complete pickling sample still retained the initial surface of pickling.In addition,it was also found that there was an inner oxide layer with a thickness of 8μm under the iron oxide scale of 6μm of 60Si2Mn hot rolled sample,but after incomplete pickling and annealing,the thickness of the loose layer of 8μm was much larger than the thickness of the iron oxide scale of the hot rolled sample,and it obviously extended to the matrix to include the inner oxide layer.Through pickling experiments,it is found that the structure of 60Si2Mn iron oxide scale is very dense,and pickling mainly corrodes the oxide scale in the form of microcracks,because the pickling time required is about several times that of conventional high-carbon steel,therefore,at the same time as the corrosion of the iron oxide scale,the internal oxide layer undergoes obvious intergranular corrosion,which together with the residual iron oxide scale,forms a loose structure after annealing leading to powder loss problem during cold rolling.Therefore,for 60Si2Mn strip,in order to avoid the occurrence of such problems,on the one hand,it is necessary to try to pi

关 键 词：弹簧钢 掉粉 氧化铁皮 内氧化层 晶间腐蚀 

分 类 号：TG335.12[金属学及工艺—金属压力加工]