Research On The Weldability Of Q460High Strength Low Alloy Steel In Electrical Engineering

As the development of the electricity construction, long-distance electricity transmissionforms a trend of high voltage, multiloop system, multiple fission and large capacity. Theexternal loads for electricity steel structure are bigger and bigger, in order to reduce costs, topromote and apply the steel with a higher strength is the technical trend for futuredevelopment. This article combines with the steel pipe pole that made of Q460steel, whichused in a planned500kV electricity transmission line in Guangdong, to research theweldability of Q460high-strength steel in this construction.Tested the mechanical properties, chemical composition of base metal and the matchingwelding material, the microstructure of base metal, mastering the basic weldability data ofsteel. The results showed that the tensile, bending, impact properties and chemicalcomposition of Q460steel can reached the standard requirement; the microstructure of Q460steel which delivered in a hot rolled state is ferrite and pearlite.Predicted cold cracking and hot cracking tendency for Q460steel welding based on thecold cracking, hot cracking evaluation criterion, do the HAZ(heat affected zone) maximumhardness test and oblique Y-groove welding crack test, T-joint cracking test. The resultsshowed that the cold cracking, hot cracking tendency of Q460steel welding is not obviousand its fabrication weldability is good.Using submerged-arc welding to butt weld Q460steel according to the common processparameters. The results showed that the tensile strength of welded joints is higher than thebase metal; the ductility and toughness can reach the standard requirement; the hardness ofwelded joints’ all regions are less than235HV10, there are no deteriorated microstructureappears in weld and heat affected zone; it has a good weldability for the application.Butt welding the Q460steel by using MAG with different welding heat input to study theproperty and microstructure, and then optimize the parameters of welding process parameters.The results showed when the heat input increased from10kJ/cm to37kJ/cm, the tensilestrength, the ductility and toughness of welded joints can reach the standard requirement; thehardness of welded joints’ all regions are less than266HV10, there are no deterioratedmicrostructures appears in weld and heat affected zone. Therefore, the microstructures andproperties of welded joints used the above welding heat input can meet the requirements.