550 MPa级微合金化高强结构钢设计与生产  

DESIGN AND PRODUCTION OF 550 MPaMICROALLOYED HIGH-STRENGTH STRUCTURAL STEEL

作　　者：董继亮 张星 张通 刘滨 Dong Jiliang;Zhang Xing;Zhang Tong;Liu Bin(HBIS Group Tangsteel Company,Tangshan 063016,Hebei)

机构地区：[1]河钢集团唐钢公司,河北唐山063016

出　　处：《河北冶金》2024年第6期52-57,共6页Hebei Metallurgy

摘　　要：介绍了屈服强度550 MPa级微合金化高强钢在中板坯连铸-连轧生产线上的设计开发与生产实践情况。3种实验方案对比结果显示:高锰低铌钛体系采用低温卷取,晶粒度11级,屈服强度668 MPa,碳化物弥散析出,冲击断口呈现明显的混合断裂形貌,聚集韧窝和准解理断裂交叉分布,冲击吸收功较低。中锰、中铌、高钛成分体系采用高温轧制和卷取,晶粒度10级,屈服强度649 MPa,碳化物在晶界析出充分,提升了韧性,但是强度降低明显;降低卷取温度后,组织细化显著,晶粒度增加至12级,屈服强度721 MPa,但纵向组织出现粗化的条状铁素体,材料组织均匀性变差;高温卷取冲击试样断口基本为韧窝形貌,而低温卷取的试样断口韧窝小且浅,且有少量解理断口。低锰、高铌、中钛成分体系下,晶粒度11级,屈服强度620 MPa,碳化物弥散析出效果最好,珠光体含量少且尺寸均匀、细小;冲击试样断口也呈现显著韧性断裂形貌,部分位置韧窝大且深,呈现微孔聚集断裂的典型形貌,但仍可观察到少量解理撕裂的形貌。试制结果表明:通过添加Nb、Ti等强化元素,可优化材料组织组成、尺寸和均匀性,实现550 MPa级产品材料强度和塑韧性最佳匹配。This paper introduces the design,development,and production practice of microalloyed high-strength steel with a yield strength of 550 MPa on the medium slab continuous casting and rolling production line.The comparison results of three experimental schemes show that the high manganese low niobium titanium system adopts low-temperature coiling,with a grain size of 11 levels and a yield strength of 668 MPa.Carbides are dispersed and precipitated,and the impact fracture surface shows a clear mixed fracture morphology,with clustered dimples and quasi cleavage fracture cross distribution.The impact absorption energy is relatively low.The composition system of medium manganese,medium niobium,and high titanium adopts high-temperature rolling and coiling,with a grain size of 10 levels and a yield strength of 649 MPa.Carbides precipitate fully at the grain boundaries,improving toughness but significantly reducing strength;After reducing the coiling temperature,the microstructure was significantly refined,the grain size increased to level 12,and the yield strength was 721 MPa;However,coarsening of strip like ferrite appears in the longitudinal organization,resulting in a decrease in the uniformity of the material structure;The fracture surface of the impact specimen taken from high-temperature coiling is generally characterized by ductile dimples,while the fracture surface of the specimen taken from low-temperature coiling is small and shallow with a small amount of cleavage fracture.Under the composition system of low manganese,high niobium,and medium titanium,the grain size is 11 grades,the yield strength is 620 MPa,and the carbide dispersion precipitation effect is the best.The pearlite content is low and the size is uniform and small;The fracture surface of the impact specimen also shows a significant ductile fracture morphology,with large and deep dimples in some positions,exhibiting a typical morphology of micro pore aggregation fracture,but a small amount of cleavage tearing morphology can still be observed.The expe

关 键 词：结构钢 微合金化 晶粒度 冲击断口 塑韧性 

分 类 号：TG142.1[一般工业技术—材料科学与工程]