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.