Metal material, process and product for welding LNG ultralow-temperature stainless steel

The invention provides a metal material process and product for welding LNG ultralow-temperature stainless steel. The components and structure of a welding material are designed to make sure that thecontent of ferrite in a weld joint is low and the proportion of residual ferrite is reduced to be equal to or less than 1.0%; during welding, a stainless steel twisted welding wire is adopted, argon arc welding is adopted for bottoming, face filling is achieved through argon arc welding or submerged arc welding, the process parameters for welding are controlled to make sure that the energy of thewelding wire is equal to or less than 13KJ/cm, and meanwhile, the formula of a welding protective gas is set; and high-frequency vibration is conducted to assisting in welding to optimize the weldingquality. By the adoption of the metal material process and product for welding the LNG ultralow-temperature stainless steel, the plasticity and tenacity of weld joint metal are obviously improved, welding residual stress is gre