Experimental Study On Influence Of Corrosion On Static And Fatigue Performance Of High Performance Steel Specimens

As a new material,high performance steel has excellent mechanical properties and can meet the requirements of modern bridge structure in terms of span and load grade.Most of the high performance steel structures have been built in the corrosive environment in the world.The corrosion fatigue damage of the structures has become serious,which causes structural bearing capacity degradation.It is reported from most experimental researches and engineering accidents that corrosion fatigue failure of the structure is attributed to corrosion fatigue fracture of steel materials.Therefore,the article uses the high performance steel Q460D and Q550E as research objects to investigate the static tensile test and fatigue test of the standard specimens which have been corroded.The main work is as follows:1?the article designs high performance steel test standard specimens which are used for the static tensile and fatigue test,and sets out a plan of accelerated corrosion standard specimen in laboratory by electrochemical method.These work laid a good foundation for the later test.2?Through the tensile testing of metallic materials at room temperature,the paper studies the influence law of the yield strength,tensile strength,percentage elongation and elastic modulus of Q460D and Q550E with the corrosion rate increases.The yielding plateau shortens gradually to disappear in the stress-strain curve and the critical mass corrosion rate is founded.The constitutive relation model is established under the influence of corrosion.The degradation degree of mechanical index of Q460D?Q550E and Q235B is analyzed quantitatively by increasing the same corrosion rate.3?the axial tensile fatigue test under different corrosion rate of high performance steel Q460D and Q550E is done.The S-N curve of five levels of corrosion rate are drawed.At the same time,the influence of different corrosion rate on fatigue life of high performance steel was analyzed.The results show that under the same stress level,the fatigue life of specimen decreases with the increase of corrosion rate,and its decrease rate increases with the increase of rust rate.Finally,the fatigue life of the high performance steel is estimated based on the S-N curve.4?The macro and micro morphology of fatigue fracture of corrosion specimens are scanned analysis by using the scanning electron microscope.The results found that the fatigue source area,the fatigue crack development area and instantaneous fracture area of the fracture present different features.The change characteristics of internal fatigue damage is of guiding significance to the fatigue strength and fatigue failure analysis of high performance steel.