Study Of Corrosion Behaviour And Optimization Methods For Linear Friction Welded Joint Of Titanium Alloys

In the future,China's combat aircraft will be increasingly active in the marine environment,which has high requirements for the service performance of the aircraft,especially the corrosion resistance.Titanium alloy's components made by linear friction welding are commonly used in aircraft.This paper investigates the corrosion behaviour of linear friction welded joints of titanium alloys by means of electrochemical corrosion,immersion corrosion and salt spray corrosion,and proposes the use of heat treatment methods to optimise the corrosion resistance of the joints.TA15/TC17 titanium alloy linear friction welding head corrosion resistance of each zone TA15 base material>weld zone>TC17 base material,corrosion products are mainly Ti O₂,as well as a small amount of Al₂O₃.Through the weight loss method calculation,it is found that the corrosion rate increases rapidly with time and then stabilizes.Salt spray corrosion after the weld area appeared more serious"crevice corrosion".TC17 side pitting corrosion is the most serious,is due to the welding area on both sides of the base material due to the presence of potential differences,the formation of galvanic corrosion,TC17 side of the base material potential is low easy to become the anode is accelerated corrosion.Salt spray corrosion after the weld area appeared more serious"crevice corrosion",because after the destruction of the oxide film,due to the junction on both sides of the sub-stable?phase and martensite?',where the?/?interface,the current density concentration,will be the first to be corroded.After the heat treatment process of 600°C+3h under vacuum and650°C+3h furnace cooling,the strength of the joint is improved due to the re-precipitation of the pin-like?phase in the heat-machine affected zone on the TC17 side.The fracture location changed from the weld zone to the TA15 parent material side,indicating that the strength of the seam area after heat treatment is greater than the joint strength of the original TA15 material.Salt spray corrosion of the weld area did not occur serious"crevice corrosion",only minor pitting corrosion occurred.The overall corrosion level is lighter than the weld state,especially after heat treatment at 650°C,the corrosion level is the lightest.Heat treatment after the weld area corrosion resistance,the reason for the TC17 side decomposition of more?phase,the original?-?interface into intermittent?-?and?-?interface,the organization is more uniform.It makes it impossible to form an excessive potential difference at the interface and the current density is not concentrated.The reduction of potential difference in each adjacent area after heat treatment and the reduction of self-corrosion current density,the overall galvanic coupling corrosion is weakened and the overall corrosion degree is weakened.Taken together,the heat treatment improves the corrosion resistance of TA15/TC17 linear friction welded joints.