碳和氮含量对大规格球扁钢组织和性能的影响  

Effect of C and N contents on mechanical properties of tempered large size bulb flat steel

作　　者：陈密达 张云祥[1] 梁丰瑞[2] 周乃鹏 陈石 CHEN Mi-da;ZHANG Yun-xiang;LIANG Feng-rui;ZHOU Nai-peng;CHEN Shi(Key Laboratory of Iron and Steel Metallurgy and Resource Utilization,Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Research Institute of Structural Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China)

机构地区：[1]武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室,湖北武汉430081 [2]钢铁研究总院有限公司工程用钢研究院,北京100081

出　　处：《钢铁》2023年第4期126-137,共12页Iron and Steel

摘　　要：在全球船舶大型化的发展背景下,中国为顺应国际市场需求,提高运输效率,对船舶材料的规格和性能提出了更高的要求,作为船舶主要型材的球扁钢,原有的成分设计已满足不了现有大规格的强度、韧性和截面均匀性等要求。为满足行业需求,研发了一种高强韧性、截面均匀性良好的18号不对称球扁钢,并采用热轧+回火工艺替代热轧+调质工艺以降低成本。试验钢为3种不同C、N成分设计的V-N微合金化钢,经工业生产成热轧态后进行实验室回火和检测。通过透射电镜、相分析等材料表征手段和力学性能检测对3种试验钢进行对比研究,研究不同C、N含量球扁钢热轧态和回火态球头和腹板部位的强度和低温韧性,并在此基础上定量计算各强化增量值。结果表明,热轧态球扁钢球头和腹板显微组织均含有多边形铁素体(PF)、珠光体(P)和粒状贝氏体(GB)。PF和P的微观结构组合提供了更好的低温韧性,而GB使试验钢韧性降低。经680℃回火2 h后,3种试验钢能在保证强度损失较小的前提下大幅度提高韧性。尤其是低碳高氮钢,由于细小的晶粒尺寸和V(C,N)析出相尺寸,使得低碳高氮钢球头和腹板的屈服强度为560 MPa左右,截面均匀性进一步提高;且由于大角度晶界含量高,低温韧性进一步改善,球头韧脆转折温度降低至-58℃,拥有优异的强韧性匹配。In the context of the development of large scale ships in the world,in order to meet the needs of the international market and improve transportation efficiency,China has put forward higher requirements for the specifications and performance of ship materials.As the main section bar of ships,the original composition design of bulb flat steel can no longer meet the requirements of the existing large scale strength,toughness and section uniformity.In order to meet the needs of the industry,a kind of No.18 asymmetric bulb flat steel with high strength and toughness and good cross-section uniformity has been studied,using the hot rolling+tempering process to replace the hot rolling+quenching and tempering technology to reduce costs.The experimental steel is a V-N microalloyed steel designed with three different C and N compositions,which is produced in industry and then tempered and tested in the laboratory.The strength and low-temperature toughness of the ball and flat of the bulb flat steel with different C and N contents in hot-rolled and tempered states are studied by means of transmission electron microscopy,phase analysis and other material characterization methods and mechanical property testing.On this basis,the strengthening increment is quantitatively calculated.The results showed that the microstructure of the ball and flat of hot rolled spheroidal flat steel contained polygonal ferrite(PF),pearlite(P)and acicular ferrite(GB).The microstructure combination of PF and P provided better low-temperature toughness,while GB reduced the toughness of experimental steel.After tempering at 680℃for 2 h,the toughness of the three kinds of experimental steels could be greatly improved on the premise that the strength loss is small.Especially for the Low C high N steel,due to the fine grain size and the size of V(C,N)precipitated phase,the yield strength of the ball head and flat of the Low C high N steel was about 560 MPa,and the cross-section uniformity was further improved.Moreover,due to the high content of large

关 键 词：球扁钢 大规格 V-N微合金化 力学性能 强韧性匹配 

分 类 号：TG142.1[一般工业技术—材料科学与工程]