主蒸汽系统P91与P22小口径管道异种钢的焊接工艺

P91与P22钢焊接性均较差,两种钢材组成的异种钢焊接接头极易出现淬硬倾向并产生裂纹。此外,由于两种钢材在材料属性以及在焊接热处理要求方面的差异,加之产品管径较小容易影响加热器安装效果从而造成热处理质量下降,最终导致该异种钢焊接接头难以获得较为理想的综合力学性能,尤其是硬度指标更难以保证。为此,通过对核电主蒸汽系统P91与P22小口径管道的材料属性、焊接性能进行分析,按照焊前准备、焊接方法及焊接材料、焊接工艺参数、焊后热处理步骤实施工艺试验,结果表明,接头焊接质量检验、力学性能检验、微观金相检验、硬度检验均满足设计以及ASME规范相关要求。通过上述措施最终确定现场施焊的焊接工艺,将其应用于实际生产后效果良好,满足P91与P22小口径管道异种钢的焊接施工要求,为现场焊接提供了技术保证。

Welding technology of P91 and P22 small diameter pipe dissimilar steel in main steam system

The weldability of P91 and P22 steel are poor,and the dissimilar steel welding joints which are made by the two kinds of steel are very easy to harden and crack. In addition,due to the differences of the two kinds of steel in material properties,welding heat treatment requirements,and the decrease of heat treatment quality caused by the smaller product diameter which is easy influence on heater installation effect,it is difficult to ensure that the dissimilar steel welding joints achieve the comparatively ideal comprehensive mechanical properties,especially hardness index. Therefore,through analyzing material properties and the weldability of P91 and P22 small diameter pipe dissimilar steel in main steam system and according to the welding preparation,welding method,welding material, welding parameters and post -weld heat treatment steps to implement technology test. The results show that joint weld quality inspection,mechanical property test,microscopic metallographic examination,hardness test meet the design requirements and ASME specifications. Through the above implementation contents,the welding technology for on-site welding is finally determined,and the welding technology achieve good result after being applied in actual production,meet the welding construction requirements of P91 and P22 small diameter pipe dissimilar steel,and provide technical guarantee for on-site welding.