Research On Self-shielded Flux-cored Wire For All-position Hardfacing

Self-shielding flux cored wire for all-position hardfacing is widely used in the actual production,especially the large and complex structure while hardfacing repaire in field operation which need all position surfacing, however, such kind of wire was still blank in the domestic market.Therefore, it was an urge need to product self-shielded flux-cored wire for all-position hardfacing. This paper had a research on the self-shielding flux cored wire using for all-position hardfacing that developing a flux-cored wire which had perfect welding process property and usability, meanwhile founding reasonable welding parameters on the basis of the influence of welding paremeters on the process property.The main aim of the slag systerm in the paper was used for self shielding and all position hardfacing,according to the reaserch, self shielding was realized by slag- gas- alloying elements joint protection,and all-position hardfacing suitability is achieved through reducing the arc length and adjusting the physical properties of slag. Based on the results, excellent slagging and gasification protection effect of wire can be attained by adding 45%- 55% of fluoride and 4%- 8% carbonate power,and BaF2 can also reduce the length of arc and molten pool,which make wire had better all-position hardfacing property; by adding 8%- 10% Al and 4-6% RE the remarkable effect of deoxidation and deonitrification can be shown,further, 4%-5% of MgO, ZrO2 and other refractory oxides can effectively improve the physical properties of slag and enhance adaptability for all-position hardfacing.Finally optimal content of Al-Mg and ZrO2 was gained by the inflence of Al-Mg and ZrO2 on slag removal, optimizing the formulation of slag system.The research of welding specification influent process performance shows that welding arc was more stable and had less spatter when the used type of current was DCEN.The transition mode of the droplet is arc-bridge transition and welding process is stable, little splash whenarc voltage is(22-27)V and welding current is(220-270)A.The Fe-Cr-Mn-Si-Al alloy system was determined on the basis of developed good process performance.The influence of the alloy composition on the microstructure and hardness was analyzed, and microstructure of deposited metal contained M+B+δ-F 、M+B、and M+B+A which had hardness between HRC32-58.In the end,the developed flux-cored wire had excellent property of self-protection and all-position hardfacing.,meanwhile welding process was stable, having small splash, and easily slag removal. In the actual application the wire has been successfully applied in online surfacing repair of rail frog.