Heat Affected Zone and Weld Metal Properties in Welding of Steels Oct01

Heat Affected Zone and Weld Metal Properties in Welding of Steels...

Heat Affected Zone and Weld Metal Properties in Welding of Steels There are many factors which control the properties of the weld metal and heat affected zone (HAZ) while welding of carbon (C) and low alloy steels. The weld metal and HAZ are frequently referred as steel weldments. The welding processes, welding consumables, and welding parameters have also influence on these properties. Properties of steel weldments are also influenced by the corrosive atmospheres and cyclic loading to which they are frequently being subjected. Heat affected zone During the selection of steels, the characteristics of the HAZ are more important than the weld metal. This is since the metallurgical and mechanical properties of the HAZ are directly linked to the selected steel. However, these properties can be adjusted by welding parameters and post weld heat treatment (PWHT). Also the metallurgical and/or weldability issues related with the HAZ characteristics are more difficult to tackle than those connected with the weld metal. Welding issues which usually occur in the weld metal can frequently be overcome by changing the welding electrode and/or other welding consumables. In comparison, difficulties with the HAZ can often be resolved only by changing the base steel, which is generally a very costly measure, or by changing the heat input. Different empirical C equivalents (CE) have been developed and utilized to evaluate the weldability and the tendency of hydrogen (H2) induced cracking (HIC) of the base steels. The most frequently used equation for CE which is also being used by the International Institute of Welding (IIW) is CE = % C + % Mn/6 + (% Cu + % Ni)/15 + (% Cr + % Mo + % V)/5. In Japan, the Ito-Bessyo composition characterizing parameter, Pcm, is more widely used. Pcm is considered...