1000MW级超超临界机组蒸汽阀材质更改可行性研究

Study on the possibility to change the material of MSV,CV and CRV used in 1 000 MW-level ultra supercritical unit

通过对9%～12%Cr耐热钢基本特点的分析认为,KT5917(12Cr铸钢)的Cr、W含量较KT5031A(9Cr-1Mo锻钢)高,所以KT5917(12Cr铸钢)的高温抗蠕变性能、抗氧化性能、抗腐蚀性能优于KT5031A(9Cr-1Mo锻钢)。但KT5917(12Cr铸钢)610℃许用应力小于KT5031A(9Cr-1Mo锻钢)的许用应力,使其阀体设计壁厚大于KT5031A(9Cr-1Mo锻钢)设计壁厚,铸造阀体还存在无损检测和焊接难度增大的问题,KT5917(12Cr铸钢)的实际使用性能要劣于KT5031A(9Cr-1Mo锻钢)。

Based on the analysis of principal characteristics of 9%- 12%Cr heat-resistant steel, this paper pointed out that the creep, oxida- tion and corrosion resistance performance of KT5917（12Cr casting） steel is better than that of KTS031A（9Cr- 1Mo forging） steel as a result of higher content of Cr and W. On the other hand, the allowable stress of KT5917 （12Cr casting） steel is 53.8 MPa, less than 56.8 MPa of KTS031A （9Cr-1Mo forging） steel. As a result, the design thickness of KT5917 （12Cr casting） valve body is more than that of KTS031A （9Cr-1Mo forging） valve. Meanwhile, the casting valve body with thicker casing also leads to the difficulties in Nondestructive Testing （NDT） and welding. The practical performance of KT5917 （12Cr casting） is inferior to that of KT5031A （9Cr- 1 Mo forging）.