执行欧洲标准S460NL高韧性结构管的开发

    Development of EN S460NL High-toughness Structure-purpose Pipe

    • 摘要: 在20Mn钢的基础上,通过添加Cr、Mo、Cu、Ni、V等合金元素,采用正火处理工艺生产了S460NL钢管材料;分析了S460NL钢管的显微组织和力学性能。结果表明:该产品的金相组织为珠光体+弥散分布着细小碳化物的铁素体基体,在拉伸过程中产生位错塞积,从而使得铁素体基体内产生位错缠结与网格结构;冲击断口呈现出典型的韧窝特征。这些微观特征决定了S460NL钢管在获得高强度的同时还具有优良的耐低温冲击韧性:屈服强度>500 MPa,抗拉强度640~680 MPa,伸长率≥22%,-50℃冲击功>100 J,满足客户要求。

       

      Abstract: The EN S460NL steel pipe is development by means of adding chemical elements like Cr,Mo,Cu,Ni and V,etc.into the 20Mn steel,and the pipe normalization heat treatment process.Microstructure and mechanical properties of the said pipe are tested.The test results reveal the facts as below.The metallographic structure of the pipes is of pearlite+ferrite matrix with dispersion-distributed fine carbides.And during the tensile testing process,the said fine carbides are dislocated and piled up,which leads to the development of dislocation tangling and network structure inside the ferrite matrix.The impact fracture has the typical tough dimple characteristics.All these microstructure characteristics enable the S460NL steel pipe to possess not only high strength,but also excellent low-temperature impact toughness,i.e.,yield strength>500 MPa,tensile strength:640-680 MPa,elongation rate≥22%,and impact energy at-50℃>100 J,and thus to have met the customer-specified requirements.

       

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