Microcracks are always present in the deposited metal of 10MnNi2MoVA steel weld seam, which affects the safety of the power plant steam pipeline. It is important to investigate the effect of heat input on the hot cracking sensitivity of the EA395-9 weld metal. In this work, the deposition of the weld metal of EA395-9 was prepared, then the hot cracking tendency of the weld with the different heat input was analyzed and observed. The results show that the moderate welding heat input can help to avoid hot cracking.

The mechanical performance of reactor pressure vessel materials is an important factor in the safety and economics of the operation of a nuclear power plant. The ductile-to-brittle transition temperature tested by Charpy impact test is the key parameter for evaluating the reactor pressure vessel embrittlement. In this article, the study of thermal aging embrittlement of temperature sets of reactor pressure vessel surveillance Ni-Cr-Mo-V steel weld metal was conducted by Charpy impact test. The thermal aging effect on the impact fracture behavior was analyzed. The impact test of the three batches of weld surveillance sample indicated that the weld metal embrittled during thermal aging. The study of impact fracture and Auger electron spectroscopy indicated that the element P segregated to the grain boundaries and lowered their cohesion strength during the long-term thermal aging. Therefore, the non-hardening embrittlement of Ni-Cr-Mo-V steel welds in a reactor pressure vessel caused by segregation of impurity elements P occurs during thermal aging.