连铸坯锻轧工艺对核电用特厚钢板内部质量和力学性能的影响

Effect of combined forging and rolling technology for continuous casting slab on quality and mechanical properties of nuclear power ultra-heavy plate

研究了采用300mm厚连铸坯锻轧生产核电特厚钢板的工艺,通过对连铸坯直轧、模铸和连铸坯锻轧3种不同工艺生产的核电特厚钢板内部质量和力学性能进行对比分析,结果表明:连铸坯直轧工艺生产的特厚钢板不能满足NB/T47013-2015《承压设备无损检测》Ⅰ级和GB/T 5313《厚度方向性能钢板》Z向断面收缩率大于35%的要求,钢板内部存在裂纹和偏析。采用锻轧工艺生产的钢板能够100%满足探伤要求,连铸坯芯部裂纹和柱状晶在高温锻造过程中能够有效焊合和破碎,并且高温加热过程对连铸坯的芯部偏析有很大程度的改善,通过锻造和轧制工艺相结合,能够解决连铸坯直轧出现的探伤不合问题,并且能替代高成本的模铸生产,进一步降低生产成本。

The technology of producing nuclear power special ultra-heavy plate with 300 mm thickness continuous casting slab was studied. The quality and mechanical properties of the plate produced by three methods of continuous casting slab rolling, casting and combined forging and roiling process were compared and analyzed. The results showed that the ultra-heavy plate produced by billet casting process could not meet the requirements of NB/T47013-2015 ＂Ultrasonic Testing for Steel Plate＂ class I and GB/T 5313 ＂Steel plates with through-thickness characteristics＂ Z35 property. Steel plate still existed micro cracks after rolling. Using billet by combined forging and rolling process could all meet the ultrasonic testing for plate. The core crack and columnar crystal could be welded and broken effectively in high temperature forging process, High temperature heating process had a great improvement in the central segregation of the continuous casting slab. The steel casting method could be replaced by this effective forging and roiling process with the production costs further reduced.