API X80管线钢异常碳化物形成机理  

Formation mechanism of abnormal carbides in API X80 pipeline steel

作　　者：孙华[1,2] 孙彦辉[1] 王帅[3] 孙瑞虹[3] 唐晋[3] 孔祥华[3] 李翔 王发仓 李士琦[1] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]南京联合钢铁有限公司,江苏南京210035 [3]北京科技大学新材料技术研究院,北京100083

出　　处：《材料热处理学报》2011年第6期45-50,共6页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(50771021)

摘　　要：针对API X80管线钢在生产实际中遇到的落锤性能较低的问题进行了分析。结果表明,该管线钢在落锤撕裂试样断口处存在大量的异常球形析出物,这些析出物为Mo、Ti、Ni等合金元素的碳化物,尺寸约为几个微米,不但削弱了这些合金元素在钢中的弥散强化作用,而且降低了管线钢的落锤撕裂性能。结合热处理实验,探讨了这些异常长大碳化物的生成机理,即钢板的冷却速度影响碳的扩散,并最终对碳化物的形成产生决定性的作用。减少析出物较好的办法是终轧后空冷至碳化物形成温区的上限附近,然后再强制水冷,保证钢板快速通过碳化物形成区间,从而抑制碳化物的异常长大行为。The spherical precipitates observed on fracture surface of unqualified drop weight tear test（DWTT） specimens of API X80 pipeline steel were characterized by SEM,AES and thermal simulation.The results show that the main chemical composition of these precipitates consists of Fe and C,some of the precipitates contain other alloying elements such as Mo,Ti,Ni,etc.Diameter of the precipitates is several micrometers.The formation of these abnormal precipitates is harmful not only to strength,but also to DWTT property.The formation mechanism of these carbides is discussed based on heat treatment experiment.The diffusion of carbon in steels is controlled by the cooling rate,so it is the key factor for the formation of abnormal carbides.When the cooling rate is not high enough,spherical carbides occur which are harmful to DWTT property.In order to prevent the formation of abnormal carbides,the steel sheet should be cooled in air to the upper limit temperature for the formation of carbides and then cooled as soon as possible to pass through the temperature region of carbide formation.

关 键 词：管线钢 落锤性能 碳化物 固相扩散 

分 类 号：TG142.4[一般工业技术—材料科学与工程]