Research On The Influence Mechanism Of Mechanical Behaviors Of The Typical Steel-aluminum Material Under The Acid Alkali Salt Corrosion Condition

In daily life,metal materials and products corrosion is a very common phenomenon,such as kitchen utensils corrosion,hull corrosion,vehicle shell corrosion,marine drilling platform,etc.As one of the main failure forms of metal materials,in natural environment,there are seawater corrosion,atmospheric corrosion,soil corrosion,etc.In industrial application,industrial media,like acid,alkali and salt,is also the main forms which causes metal corrosion.According to the statistics from Chinese Academy of Engineering,the economic loss caused by material corrosion can reach up to 480 billion per year in China.Based on the British marine survey,in terms of ocean platform,the average reduction of annual oil production is up to 13% due to corrosion fatigue failure of materials.Therefore,the research on the effect of mechanism and behavioral mechanics of metal materials under corrosion condition is of great academic significance and good application prospect on assessing the service reliability,service life of metal materials and products and improving corrosion resistance of metallic materials.Based on the comprehensive analysis of development status at home and abroad about material environmental test,this paper demonstrates the experimental study on typical metal materials,like steel and aluminum,through simulating corrosion environment of metallic materials in industrial media.The main corrosive media in these experiments contain of acid,alkali and salt,and take different corrosion solvent,concentration and time as test parameter.And mechanical property test is carried out to material sample before and after corrosion by using multiple load and multiple physical field coupling material microcosmic mechanical properties of in situ testing instrument developed by research group,and compare and analyze the results.Combined with finite element simulation analysis,determination and analysis of surface element content,observation and analysis of microstructure and other methods,comprehensively study and analyze the action mechanism of different corrosion environment to mechanical properties of metallic materials and failure behavior.Based on the comprehensive analysis of development status at home and abroad about material environmental test,this paper demonstrates the experimental study on typical metal materials,like steel and aluminum,through simulating corrosion environment of metallic materials in industrial media.The main corrosive media in these experiments contain of acid,alkali and salt,and take different corrosion solvent,concentration and time as test parameter.And mechanical property test is carried out to material sample before and after corrosion by using multiple load and multiple physical field coupling material microcosmic mechanical properties of in situ testing instrument developed by research group,and compare and analyze the results.Combined with finite element simulation analysis,determination and analysis of surface element content,observation and analysis of microstructure and other methods,comprehensively study and analyze the action mechanism of different corrosion environment to mechanical properties of metallic materials and failure behavior.Based on the microstructure observation and composition analysis on corroded mental surface,it can be found when the steel under the hydrochloric acid corrosion or aluminium under hydrochloric acid and sodium hydroxide corrosion,there are several tiny cracks of different depth on the corrosion surface,on which,the corrosion morphology is irregular,and the degree of acid corrosion is relatively deeper.Furthermore,the material surface composition content also changes obviously after corosion,of which,the relative content of iron and aluminum decreases,but the content of other impurity rises.The relative content of surface oxygen increases due to corrosion or oxidation.This paper demonstrates the mechanical property test of multi load thermal coupling on steel and aluminium metallic materials before and after corrosion.It can be found when the torsion test is conducted in elastic stage with pre-tension,the mechanical performance like torsional yield strength and torsional strength has a dawnward tendency during torsion test.However,after pre-tension in plastic stage,the mechanical performance changes slightly because cold-working hardening happens.Similarly,in the orsion test with pre-tension,while the pre torsion angle appears within plastic stage,the mechanical performance like torsional yield strength and torsional strength after corrosion also changes less slightly than that before corrosion also due to the cold-working hardening.Nevertheless,in the thermal coupling test,the changes of mechanical performance of materials improves apparently compared with that before corrosion,because the material is effected by temperature softening.