| High strength low alloy steels occupy an important position in shipbuilding,bridge,oil pipeline and other industries owing to their good strength,plasticity,toughness and weldability.The texture of high strength low alloy steels has an important influence on the processing and performance of the material.This paper mainly explored the effect of different treatment processes on the microstructure evolution and the effect of different texture configurations on the mechanical properties of the material.The textures of the samples treated by different processes were measured by XRD and EBSD.Then,the corresponding relationship between the processing technology,the texture and the mechanical properties were obtained by comparing and analyzing the test results.Firstly,different austenitizing temperatures were selected to investigate the austenitizing process of the materials.Two representative samples austenited at 850? and 950? were selected for macro-texture analysis and mechanical properties test.The results indicated that the average grain size of the material increased slowly with the increase of austenitizing temperature.The material was relatively stable,only when the austenitizing temperature was more than 1000?,the grain began to appear obvious coarsening,and the grain size was polarized.After austenitizing at 850?,the densities of both {111} and {223} textures all increased,and both tensile and impact properties were improved.After austenitizing at 950?,the texture of {111} was improved and only some properties are strengthened.In order to obtain the relationship between the hot rolling processes,the texture and properties of the high strength low-alloy steel,the high strength low-alloy steel treated with different values of hot rolling temperature and hot rolling deformation.The results indicated that the temperature of hot rolling has little effect on the texture type and density,the performance is mainly determined by the microstructure change when the hot deformation is a constant value of 50%.The deformation of hot rolling is 30%,the recrystallized texture and deformation texture are mainly contained in the material when the hot rolling temperature is a constant value of 850?.The density of {111},{112} and {223} and {001}<110> texture increased greatly,and the large grain boundary(?15°)and the number of CSL ?3 grain boundary increased.It is found that the tensile properties of materials increase greatly due to the increase of texture of {111},{112} and {223}.The impact ductility is sensitive to texture of {001}<110>,and the specimen is cleavage fracture on {001} surface,resulting in the decrease of impact toughness of materials.When the deformation of hot rolling is 50%,the texture is basically unchanged,which shows that the deformation of hot rolling is not proportional to the change of texture density.Deformation help produce texture adequate when the temperature of hot rolling fixed.In order to obtain the relationship between the cold rolling process,texture and properties of the high strength low-alloy steel,different cold rolling deformations were performed.The study shows that the texture type of the material is not modified as deformation increases,although the texture density increases.It is opposite with the case for the different hot rolling deformation.When the cold rolling deformation is 50%,texture density,dislocation density and material strength increase,but elongation decreases.It shows that if texture is used to improve material performance,controlling the dislocation density inside the material is necessary.Based on the above analysis,cold deformation before heat treatment will contribute to promote recrystallization texture formation and enhance the properties of the material.In addition,it is also favorable for hot rolling in the ?/? two-phase region.The selection of hot rolling deformation should follow the principle that the recrystallized texture and the deformation texture can match each other in the materials. |
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