Should be based on parent material chemical composition, mechanical properties , combined with the pressure vessel welding performance and structural characteristics , conditions of use and welding methods considering the selection of welding materials, if necessary, be determined experimentally . Weld metal properties should be greater than or equal to the corresponding value of the base material standards or to meet minimum technical conditions prescribed pattern . Gas Shielded Welding Wire material standards or product samples are listed on the welding performance of the deposited metal ( excluding base metal ) performance, but performance depends on welded joints weld metal ( including welding ; material deposited metal and base metal ) and welding process , there is no any welding material in the welding process can act on welded joints in the heat affected zone and change its properties, from selection of welding materials , it can only consider the weld metal properties needed to ensure the performance of welded joints welded process ( especially post-weld heat treatment line energy ) cooperation.