700MPa级汽车大梁钢混晶组织问题研究  

Research of mixed crystal structure of 700 MPa grade plate for automobile beam

作　　者：张继永 李红俊 申震 贾改风 李爱民 ZHANG Jiyong;LI Hongjun;SHEN Zhen;JIA Gaifeng;LI Aiming(Technology center,Hanbao Company,HansteelCo.,Lid.,HBIS Group,Handan 056015.China;Hot Strip Rolling Plant,Hanbao Company,HansteelCo.,Lid.,HBIS Group,Handan 056015.China)

机构地区：[1]河钢集团邯钢技术中心,河北邯郸056015 [2]河钢集团邯钢邯宝热轧厂,河北邯郸056015

出　　处：《轧钢》2021年第1期84-88,共5页Steel Rolling

摘　　要：针对邯钢700 MPa级汽车大梁钢存在不同程度混晶组织的问题,通过对铸坯、中间坯和成品钢板组织及生产工艺的研究,可以明确铸坯原始组织存在枝状晶和块状混晶组织,并且加热工艺不合理、粗轧单道次压下率偏小以及精轧前机架进入部分再结晶区轧制是导致成品钢板混晶组织的主要原因。为此,对生产工艺进行了优化,板坯出炉温度按目标中上限控制,板坯最短在炉时间不低于170 min,均热段停留时间控制在40~70 min;调整R_2机架最后3道次负荷分配来提高单道次压下率,实际压下率按23%~30%控制,为奥氏体充分再结晶提供必需的变形量;通过调整精轧穿带速度和增开机架间冷却水来提高轧制速度,使成品钢板混晶组织问题得到明显改善且提高了低温冲击性能,减少了用户加工开裂和后续服役疲劳断裂的风险。Aiming at the problem of mixed crystal structure in different degrees in 700 MPa automobile beam steel of Handan Iron and Steel Co.,Ltd.,through the research on the structure and production process of casting slab,intermediate slab and finished plate,it is clear that the original structure of casting slab has dendrite and block mixed crystal structure,and that the heating process is unreasonable,the reduction rate of single pass of roughing rolling is too small,and several finishing stands enter into partial recrystallization zone for rolling are the main reasons of mixed crystal structure of plate.Therefore,the production processes were optimized.The slab discharge temperature was controlled according to the upper limit of the target.The shortest time in the furnace was not less than 170 min,and the time in the soaking section is controlled at 40~70 min.the single pass reduction rate was improved by adjusting the load distribution of the last three passes of R2 stand.The actual reduction rate was controlled at 23%~30%,which provides necessary deformation for austenite recrystallization.By adjusting the rolling speed and increasing the cooling water between the stands,the rolling speed was increased,the mixed crystal structure of the finished plate was obviously improved,the low-temperature impact property was improved,and the risks of processing cracking and subsequent service fatigue fracture were reduced.

关 键 词：混晶组织 汽车大梁钢 加热工艺 粗轧压下率 精轧轧制速度 再结晶 组织性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]