Study On Process And Joint Properties Of Surfacing Corrosion Resistant Copper Alloy On High Strength Steel Surface With Interlayer

When high strength steel is surfacing copper alloys,due to the large heat input of conventional fusion welding methods,the infiltration cracks and the high dilution rate of the welds are often found in the heat-affected zone of base metal.Therefore,the CMT welding method is used,which is characterized by the heat of welding.Lower input,less impact on the base metal.When CMT was directly used to surfacing aluminum bronze on the surface of 921 high strength steel,the penetration crack on the joint interface was still prominent.Q235 steel and 409 L steel were selected as the interlayer material to improve the penetration crack of the 921 high-strength steel and aluminum bronze surfacing interfaces and reduce the dilution rate of the surfacing layer.When using CMT directly on the surface of 921 high-strength steel,the wire feeding speed is 6m/min,the interface is melted and brazed without penetration.At this time,the interface has no penetration cracks,but the interface shear strength is not enough.With the increase of wire feeding speed,the depth of penetration at the interface increased,and the number and size of penetrating cracks increased.When the wire feeding speed reached 8 m/min,the crack size reached about 100 ?m.Aluminum bronze is surfacing on the surface of Q235 steel as an interlayer material,when the wire feeding speed is 6m/min,the interface has a penetration depth,but the penetration depth is small,the penetration crack is not obvious,and the wire feeding speed increases to 8m/min.At the time of minimum wire feeding speed,the infiltration crack was obvious and the crack size was about 20?m.Compared with the direct welding on the steel surface of 921,the infiltration crack size has been significantly reduced.When aluminum bronze is surfacing on the surface of the interlayer material 409 L steel,when the wire feeding speed is 6m/min,the interface has a deep penetration,no penetration crack is generated at the interface,and a thermal stress crack with a length of about 15?m is generated.As the wire feeding speed increases,the number of thermal stress cracks decreases in size.This is because the 409 L steel is pure ferritic steel,liquid copper alloy and ferrite phase does not infiltrate,does not generate infiltration cracks,and due to the great difference in thermal conductivity,when the heat input is low,the copper-steel thermal stress is greater,Thermal stress cracks are generated,the wire feed speed increases,the heat input increases,the cooling slows down,the thermal stress difference at the copper-steel interface decreases,and the number of cracks decreases in size.And the Q235 steel and 409 L steel two kinds of welding head corrosion resistance of the copper alloy surface than the direct corrosion resistance of the 921 steel surfacing welding head.After comprehensive comparison,409 L steel was selected as the intermediate layer to perform the composite joint performance test.ER409 L welding wire matched with 409 L steel was selected to be firstly deposited on the surface of 921 high-strength steel,and then an aluminum bronze was surfacing on the middle layer.Because 409 L steel and ER409 L welding wire components are not exactly the same,so the interface is not the same.The immersed cracks with a length of 3?m were generated at the interface between the ER409 L wire and the aluminum bronze,and the number was small.At the same time,the corrosion resistance of the aluminum bronze surface of the composite welding joint has been greatly improved.And shear strength also meets expectations.