The impact toughness of steel refers to the ability of steel to absorb mechanical kinetic energy in the process of fracture under impact load.It is a mechanical property to measure the impact resistance of steel.Low temperature and stress concentration can lead to brittle fracture.The impact toughness index of steel is usually obtained by impact test of standard specimen.

The weldability of steel is to obtain a good welding joint under certain welding conditions.Welding performance can be divided into two categories: welding performance and welding performance.The welding performance in the welding process refers to the sensitivity of the weld and the metal near the weld when there is no hot crack or cooling shrinkage crack.Good welding performance means that under certain welding conditions, no cracks are found in the weld metal and nearby base metal.Weldability refers to the impact toughness of the weld and the ductility of the heat affected zone.It is required that the mechanical properties of weld and heat affected zone steel structure manufacturer shall not be lower than that of base metal.The welding performance test method is used in the welding process of our country, and the practical test method is used in the welding performance test.

There are many factors that affect the durability of steel.Firstly, the corrosion resistance of steel structure is poor.Protective measures must be taken to prevent corrosion and corrosion of steel.Protection measures include: regular maintenance of steel paint, galvanized steel plate, in the presence of acid, alkali, salt and other strong corrosive media, special protection measures, such as “anode protection” measures for offshore platform structure, to prevent sheath corrosion and fixation.On the jacket zinc ingot, the seawater electrolyte will automatically corrode the zinc ingot first, thus protecting the function of the steel jacket.Secondly, since the failure strength of steel under high temperature and long-term load is much lower than that under short-term load, the long-term strength of steel under high temperature should be measured.As time goes on, the steel hardens and becomes brittle, that is, “aging.”.The impact toughness of test steel under low temperature load shall be tested.

The strength indexes of steel are elastic limit e, yield limit y and tensile limit U.High yield strength can reduce structure weight, save steel and reduce cost.The tensile strength u is the maximum stress of steel before failure.At this time, due to the large plastic deformation, the structure loses its serviceability, but the structure has large deformation and does not collapse, which meets the requirements of rare earth earthquake resistance.The value of σ U / σ y can be used as a parameter of steel strength reserve.