Dissimilar steel welded joints are common joint types for welding structures such as boilers and pressure-bearing equipment.Through the test research on the welding joint of 20MnMo and SA-299B

the CHE557R（GB/T5117 E5515） electrode was selected for the oblique y crack test. The welding test plate

the post-weld heat treatment and the joint mechanical property test

the hardness test and the metallographic phase were carried out according to the proposed welding process. The test results show that 20MnMo and SA-299 have good welding performance;the weld microstructure is mainly acicular ferrite +pearlite structure

and the parent materials of 20MnMo and SA-299B are pearlite+ferrite

the heat effect zone is mainly bainite structure

and the carbides in the 20MnMo side heat affected zone are precipitated

showing different regional differences in joints:joint hardness from 20MnMo base metal and heat affected zone

weld seam

SA-299B thermal shadow zone and the mother material also shows non-uniformity;tensile strength

bending perf-ormance and impact toughness of welded joints meet the requirements of NB/T47014 "Welding Process Assessment for Pressure Equipment". However

the impact absorption work of the 20MnMo side heat affected zone is relatively low

which is in good agreement with the microstructure of the region. It shows that the toughness reserve of 20MnMo and SA-299B dissimilar steel welded joints is weak in the 20MnMo side heat affected zone

which has good guiding significance for engineering application of 20MnMo and SA-299B.