超大尺寸平板硫化机特厚复合钢板开发

Development of extra-thick composite steel plate for extra-largesize plate vulcanizing machine

采用焊前预热、真空电子束焊接、低加热速度加热、合理道次压下率轧制和热处理工艺,成功生产出超大尺寸(170 mm×3420 mm×10620 mm)平板硫化机45钢特厚复合钢板,其平均硬度达到199 HB。并且,上、下复合面位置与整板中间1/2位置的基体夹杂物分布相似,冶金结合效果良好;回火后组织较为均匀,板材达到GB/T 2970-2016中I级探伤要求。研究发现,不合理的焊前预热速度会加剧真空焊接过程中的坯料变形,在温度较低、组织应力较大的情况下容易产生表面区域裂纹,且该类裂纹在轧制过程中难以消除,需合理控制焊前预热速度。

By adopting pre-heating before welding,vacuum electron beam welding,heating at low heating rate,rolling with reasonable pass reduction rate and heat treatment process,the 45 steel ultra-thick composite steel plate of extra-large size(170 mmx3420 mmx 10620 mm)plate vulcanizing machine was successfully produced.Its average hardness is 199 HB.The distribution of matrix inclusions in the upper and lower composite surfaces is similar to that in the middle of the whole plate,and the result of metallurgical bonding is good.The microstructure is relatively uniform after tempering,and the plate meets the requirements of level I flaw detection in GB/T 2970-2016.However,the research shows that the unreasonable pre-heating speed before welding aggravates the deformation of blank during the vacuum welding.When the temperature is low and the microstructure stress is large,the cracks at surface areas occur easily.In addition,these types of cracks are difficult to eliminate during the rolling process,so it is necessary to control the pre-heating speed be-fore welding reasonably.