Mainly pearlite steel and austenitic steels with different coefficients of linear expansion and poor thermal conductivity of austenitic steels produced. Welded austenitic steel with pearlite steel should be used austenitic chrome-nickel content than high-alloy steel base metal welding materials, and even use linear expansion coefficients ranged between pearlite steel and nickel alloy austenitic steel Aluminium Welding Electrodes consumables to reduce residual stress. Welding materials shall meet the technical requirements of drawings in accordance with the provisions by welding procedure qualification JB4708. Because welding, flux national standard performance tests without bending, welding, mechanical properties test plate heat flux specification and product specification are not identical post weld heat treatment, with a lot of steel, a far cry from requiring welding "by welding procedure qualification by JB4708 "to ensure that the pressure vessel by welding standards through performance testing, but does not require welding furnace batch by welding procedure qualification.
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.