P91钢连铸圆坯热轧钢管表面开裂的原因分析  

Analysis of Surface Cracks on the Hot-rolled Steel Pipe Produced by Continuously Cast Round Billet of P91 Steel

作　　者：宋景凌[1] 田汉蒲[1] 陈代兵[1] Song JingLing;Tian HanPu;Chen DaiBing(Hengyang HuaLing Steel Tube Co.,Ltd.,Hengyang Hunan 421001,China)

机构地区：[1]衡阳华菱钢管有限公司,湖南衡阳421001

出　　处：《上海金属》2018年第5期32-36,共5页Shanghai Metals

摘　　要：采用电弧炉(EBT)→炉外精炼(LF+VD)→弧形连铸的工艺生产P91钢圆管坯,为周期连轧管机组提供坯料。使用Φ500 mm连铸圆坯轧制Φ559 mm×35 mm高压锅炉用钢管时,钢管外表面出现裂纹,大部分钢管经局部修磨后探伤合格,但仍有部分钢管因修磨超过壁厚负公差而报废。对本批次钢管、连铸坯取样,进行了金相、酸浸、扫描电镜及能谱等测试,以分析并确认缺陷产生的原因。结果表明,钢管表面裂纹是因连铸坯出现了表面裂纹所致,结晶器内冷却不均,造成连铸坯表面凹陷处存在细小裂纹,形成的δ铁素体增大了钢管加工变形时产生裂纹的倾向。The EBT+LF/VD+Curved-CC made P91 steel round billets were used for tube cycle rolling mills.Cracks were found in the outer surface of?559 mm×35 mm high-pressure boiler pipes rolled from the P91 steel round billets with 500 mm in diameter.Most of the steel pipes were qualified after being partially repaired.Some of the steel pipes were still scrapped because of the wall thickness outside negative tolerance.Samples of this batch of steel pipes and continuously cast billets were taken for metallography,acid leaching,SEM and EDX tests to analyze and confirm the causes of the defects.The results showed that the surface crack of steel pipe was caused by surface cracks on continuously cast billet,uneven cooling in the mold led to the formation of small cracks on the concave surface of continuously cast billets,and the formation ofδ-ferrite increased the tendency to crack when steel tube was processed.

关 键 词：连铸圆坯 热轧钢管 表面裂纹 原因分析 

分 类 号：TF777[冶金工程—钢铁冶金] TG335[金属学及工艺—金属压力加工]