Effects of Electron Beam Local Postweld Heat Treatment on Microstructure and Properties of 30CrMnSiNi2A Steel Welded Joints

摘要

To improve the microstructure and properties of the electron beam welded joints, the vacuum or furnacernwhole post weld heat treatment (FWPWHT) usually should be done on it. The electron beam local post weld heatrntreatment (EBLPWHT) is a rather new heat treatment procedure that provides the advantages of high precision,rnflexibility and efficiency, energy saving and higher productivity. In this paper, the microstructure, mechanicalrnproperties, fracture toughness and fatigue properties of electron beam welded joints of 30CrMnSiNi2A steel inrnas-welded (AW) and EBLPWHT conditions have been investigated respectively. The results show that thernmicrostructures of different zones of joints in as-welded condition are changed by EBLPWHT procedure, in whichrnthe welds from coarse needle martensite into lath-shaped martensite; the main structures of heat affected zonesrn(HAZ) from lath-shaped martensite into lower bainite. The properties of welded joints can be improved by thernEBLPWHT in some extent, especially the fracture toughness of the welds and the fatigue crack resistance of weldedrnjoints can be saficicantly improved. However a .more appropriate heat treatment parameters of the EBLPWHT havernto be studied in order to increase the mechanical properties of base metal near by the HAZ.