Study On Microstructure And Properties Of New Austenitic Stainless Steel After Cold Deformation And Annealing

At present,the bending technology of nuclear power main pipe can be divided into hot bending and cold bending.The advantages of cold bending are simple operation,grain size will not grow,work hardening can also improve the strength of the material.But there are also poor plasticity,easy to crack,bending load and other shortcomings.The grain size of main pipe forgings should be no less than grade 2.The solution temperature is generally in the range of 1050?1150?.Only static recrystallization after deformation can refine grains.Therefore,it is of great engineering significance to study the effects of cold deformation and annealing heat treatment on the microstructure and mechanical properties of basic composition test materials.In this paper,by comparing and studying the intergranular corrosion properties of316LN stainless steel,Z3CN20-09M,nitrogen containing test material and base component test material,the microstructure and mechanical properties of base component test material after cold deformation and annealing at different temperatures,the research results are as follows:The corrosion rate of the nitrogenous test materials is the lowest,followed by 316LN stainless steel,indicating that the two test materials have better intergranular corrosion resistance,while the corrosion rate of Z3CN20-09M is the highest and the difference between Z3CN20-09M and the other three is large,indicating that the intergranular corrosion resistance of Z3CN20-09M is poor.The stacking fault energy of the austenitic stainless steel used in this experiment was calculated to be 73m J/m~2at room temperature.The hardness value of the test material increases with the increase of deformation.After EBSD analysis,with the increase of deformation,the proportion of small Angle grain boundary of test material increases,and the proportion of special grain boundary decreases.The proportion of?3 grain boundaries is the highest in the special grain boundaries.With the increase of deformation,the proportion of?3grain boundaries decreases,and the proportion of?9 and?27grain boundaries increases slightly.With the increase of deformation,the residual stress in the test material also increases.Following the increase of annealing temperature,the microhardness of the test value is declining trend,the grain size of test material rises gradually,but the small Angle grain boundary test material of falling,in the test material,in?3 grain boundary of the highest,while?9,?27grain boundary ratio is very low,and with the increase of annealing temperature,?3,?9 and?27proportion increases,three?largest rise in the proportion of the grain boundary,and?9 and?27 grain boundary accounted for less than the growth rate.The orientation difference Angle of the materials at different annealing temperatures mainly concentrates at2.6°and60.2°.With the increase of annealing temperature,the residual stress in the test material decreases continuously,and there is almost no residual stress in the test material when it reaches 1025?.The above research enriches the research results of austenitic stainless steel for main pipeline,and can provide some theoretical guidance for engineering practice,which is of great significance for the steady development of nuclear power in China.