【作者】 王凯；

【导师】 张明；

【作者基本信息】 燕山大学 ， 材料学， 2021， 硕士

【摘要】 中碳高锰钢以其高强度、优异的延展性而被广泛应用。现代工业的快速发展对中碳高锰钢性能提出了更高的要求,同步提升材料强塑性一直是材料领域研究热点。本文以0.39C-11.71Mn-2.18Al(wt.%)中碳高锰钢为研究对象,基于层错能设计试验工艺,研究了变形工艺对中碳高锰钢组织及力学性能的影响规律,得到如下结果:试验钢经单一温变形(WR)处理后,其强度和硬度显著提升,并且随温变形温度的降低,试验钢强度提高,塑韧性逐渐降低。温变形过程中引入了高密度位错,同时随变形温度的降低,位错增殖幅度提高。在拉伸过程中高密度位错产生的位错强化作用以及发生的TRIP效应均有利于强度的提高。试验钢经单一冷变形(CR)处理后,其强度和硬度显著提升,随冷变形量的增加,试验钢强度逐渐升高,而塑韧性下降。由于试验钢在室温下的层错能较低,为23m J/m~2,因此在冷变形过程中的塑性变形方式以孪生为主,产生形变孪晶的同时引入了高密度位错。冷变形量的增加进一步提高了位错密度和形变孪晶的数量,同时孪晶的类型也随冷变形量的增加由一重孪晶转变为多重孪晶。位错密度的提高、形变孪晶数量及类型的增加是提高强度的主要原因。试验钢经复合变形(WR+CR)工艺处理后,其屈服强度和抗拉强度同时显著高于经单一温变形和冷变形处理后的强度。在复合变形工艺中,温变形温度相同时,随冷变形量的增加,硬度、强度升高,塑性先下降后小幅升高;冷变形量相同时,随温变形温度的升高,硬度、强度降低,塑性升高。在温变形过程中产生的位错和层错,冷变形过程中产生的大量位错和形变孪晶,在拉伸过程中均有助于提升试验钢的强度。在冷变形及室温拉伸过程中发生的TRIP效应,有助于试验钢保持良好的塑韧性。更多还原

【Abstract】 Medium carbon high manganese steel is widely used due to its high strength and excellent ductility.The rapid development of modern industry has put forward higher requirements on the properties of medium carbon and high manganese steels.The simultaneous improvement of material strength and plasticity has always been a research hotspot in the field of materials.This paper takes 0.39C-11.71Mn-2.18Al(wt.%)medium carbon high manganese steel as the research material.Based on the stacking fault energy,the test process is designed.Study the influence of deformation process on the microstructure and mechanical properties of medium carbon high manganese steel,the following results are obtained:After the test steel is treated with a single warm rolling(WR),its strength and hardness are significantly improved,and with the decrease of the warm rolling temperature,the strength of the test steel increases,and the plastic toughness gradually decreases.High-density dislocations are introduced in the process of warm rolling,and at the same time,as the deformation temperature decreases,the range of dislocation multiplication increases.The dislocation strengthening effect of high-density dislocations during the stretching process and the TRIP effect that occur are all conducive to the improvement of strength.After the test steel is treated with a single cold rolling(CR),its strength and hardness are significantly improved.As the amount of cold rolling increases,the strength of the test steel gradually increases,but the ductility decreases.Because the stacking fault energy of the test steel at room temperature is relatively low,23m J/m~2,the plastic deformation during the cold rolling process is dominated by twins,which produces deformation twins and introduces high-density dislocations.The increase in the amount of cold rolling further increases the dislocation density and the number of deformation twins.At the same time,the type of twins also changes from single twins to multiple twins with the increase in cold rolling.The increase in dislocation density and the increase in the number and types of deformation twins are the main reasons for the increase in strength.After the test steel is processed by the composite deformation(WR+CR)process,its yield strength and tensile strength are both significantly higher than the strength after a single warm rolling and cold rolling treatment.In the composite deformation process,when the warm rolling temperature is the same,as the amount of cold rolling increases,the hardness and strength increase,and the plasticity first decreases and then slightly increases;when the amount of cold rolling is the same,with the increase of the warm rolling temperature,the hardness and strength decrease,toughness rises.The dislocations and stacking faults produced in the process of warm rolling,a large number of dislocations and deformation twins produced in the process of cold rolling,all contribute to the improvement of the strength of the test steel during the stretching process.The TRIP effect that occurs during cold rolling and room temperature stretching helps the test steel maintain good plasticity.更多还原