Mechanical Properties Of Q690 High Strength Steel Matrix Under Periodic Wetting And Hot And Humid Status

Many special steel structures under high intensity Marine corrosion environment for a long time are difficult to avoid corrosion through protective measures.The formation of irregular rust pits on the steel surface weakens the fracture toughness and plasticity of the material,accelerates the crack initiation and expansion,causes local stress concentration of steel,and has a great impact on its mechanical properties.In this paper,the corrosion of Q690 high-strength steel base metal connection specimen under periodic wetting and hot and humid conditions is taken as the research object to study the influence of corrosion on the mechanical properties of Q690 high-strength steel base metal connection specimen.The research results in this paper can provide technical support and theoretical basis for the evaluation of mechanical properties of existing high strength steel joints.The main research work of this paper includes the following aspects:(1)By means of indoor periodic artificial accelerated corrosion,Q690 high-strength steel base material joint specimens were corroded rapidly for 100 days under periodic wetting and hot and humid conditions.High strength steel parent metal to rust Q690 connection specimens as the research object,by using laser confocal microscope in different corrosion cycle the identity of the parent metal specimen surface morphology of partial scanning,and has carried on the analysis of mathematical statistics,the scanning data obtained the specimen surface morphology characteristics and the rust pit size and related parameters as the corrosion time.(2)Using ht-2402 computer controlled material testing machine,monotonic tensile test was carried out on 12 specimens with different corrosion cycles,and the influence of corrosion on stress-strain curve,failure mode and mechanical property parameters of the specimens was studied.The relationship between the mechanical performance indexes and the corrosion quality loss rate was established,and the statistical mechanical property degradation rule was analyzed in combination with the morphology scan data.Based on the secondary plastic flow model,the constitutive model of Q690 steel with different corrosion degrees was established.(3)Low cycle loading tests of 12 specimens with different corrosion cycles were carried out to study the influence of corrosion on hysteretic curve,skeleton curve and hysteretic energy consumption of high-strength steel base metal connection specimens.The ramberg-osgood model was used to establish the relationship between the parameters of the cyclic skeleton curve model of corroded steel and the corrosion quality loss rate.With the help of large finite element software(ABAQUS),the finite element simulation of monotone tensile and corroded high strength steel base material specimens was carried out,and the results were compared and analyzed.On the basis of experiment and finite element analysis,the law of mechanical property degradation of corroded high strength steel base material is studied.