Research On Flux-cored Wire For Repairing 5CrNiMo Hot-working Die And Performance Of The Deposited Metal

Repairing dies by surfacing can greatly reduce the industrial production costs,shorten the manufacturing cycle of products,with high practical significance and economic value.Nowadays,some scholars are doing research about repairing the5CrNiMo hot-working die with stick electrode.Compared with manual arc welding,semi-automatic CO₂ gas shielded welding with flux cored wire is much more efficient and easy to operate.However,the flux-cored wire for repairing 5CrNiMo hot-working die with CO2-gas shielding arc welding is rare,limiting the development of the CO2gas shielded welding.This paper aims to develop a kind of flux-cored wire for repairing 5CrNiMo hot-working die with CO2-gas shielding arc welding.Compared with the 5CrNiMo steel,the surfacing metal has a low carbon content and a high content of alloy like Cr?Mo?V and so on.Besides,we add some NaF into the flux cored wire to improve the performance of the welding process.We surface 4 layers,with 5 welds in each layer,on Q235 steel by using an optimization welding procedure specification.Getting the component of each alloy in surfacing metal by the X-ray fluorescence.Researching the influence of NaF content on welding arc stability by high-speed photography.We test the hardness by Rockwell hardness tester and then observe the microstructure by optical microscopy and scanning electron microscopy.Measuring the weight-loss of the sample at 600?by BRUKER CETR-UMT wear tester.Though the tests above,we get the results as follows:?1?The ionization potential of Na is low.While we take NaF as arc stabilizer,it can increase the charged arc in the welding arc which can stabilize the welding arc effectively and reduce the welding splash.It has the most stable welding arc with the least welding splash when the content of NaF is 1.5%.?2?The organization of surfacing metal is mainly martensite and residual austenite.The hardness of surfacing metal is higher than forged 5CrNiMo.The experiments show that wear rate of surfacing metal is 18.75%less than the 5CrNiMo forged at 600?.In the process of heat treatment,the alloying elements such as Mo and V can combine with carbon and nitrogen,which can improve the hardness and the performance of high temperature wear of surfacing metal.It has the highest hardness and the best performance of high temperature wear while the temperature of the heat treatment is550?.?3?In the case of as welded,the surfacing metal has great stability under high temperature.There are precious few differences of yield strength and tensile strength while the experiments are carried on at the room temperature or 600?.