轧制及退火对单相微纳结构304奥氏体不锈钢组织和性能的影响及其作用机制
发布时间：2019-03-24 11:19
【摘要】：本文在铝热反应的基础上通过添加过量的Fe_2O_3制备出单相微纳结构304奥氏体不锈钢,并研究了轧制温度对所制备单相微纳结构304不锈钢组织和性能的影响;以及退火时间对轧制后的组织和性能的影响及作用机制。通过分析不锈钢中的纳米晶奥氏体、亚微米晶奥氏体晶粒尺寸、体积分数的变化,以及铁素体体积分数的改变等,根据研究结果表明了微纳结构组织的演化机制以及对相应的力学性能的影响。1.当Fe_2O_3过量比例由2.5%逐渐增加到7.5%时,所制备出的微纳结构304不锈钢XRD显示主要相为奥氏体,其中包含有少量的铁素体,且铁素体含量在Fe_2O_3过量5%时达到了最小值,其中少量的铁素体分布在胞状奥氏体的晶界处。EDS显示随着Fe_2O_3过量比例的增加,合金中的Al元素含量先下降后又有所回升,同时也会引起Cr、Ni等其他合金元素含量的下降。2.Fe_2O_3过量5%的微纳结构304不锈钢在高温1000℃、低温700℃下不同变形量轧制时,都未发生相变,组织中包含主要的奥氏体相和少量的铁素体相。不同轧制情况时,铁素体体积分数无明显变化,纳米晶奥氏体在轧制过程中发生长大,引起其晶粒尺寸增大,体积分数减小。亚微米晶在轧制过程中长大和破碎同时进行,其晶粒尺寸与体积分数与轧制温度、变形量有关。轧制后相比铸态,材料力学性能大幅上升。在高温轧制时可达到最大抗拉强度1410MPa。当在700℃变形量为60%轧制时,受微纳结构晶粒尺寸影响,材料的屈服强度相比于高温1000℃时有所提高,但是延伸率略微偏低。3.Fe_2O_3过量5%的微纳结构304不锈钢在1000℃-40%-700℃-60%轧制后再在800℃经不同时间退火处理,结果表明晶粒尺寸从轧制态到退火态迅速升高然后缓慢增加,晶粒尺寸长大行为更多依赖于温度,随退火时间延长,晶粒尺寸增长比较缓慢。退火过程中材料中没有新相生成,退火后的试样组织中包含奥氏体和少量铁素体。退火后材料强度有所下降,但是塑性得以提升。其中,在800℃退火8h后材料良好的综合性能,归因于组织中形成的双尺度结构。
[Abstract]:In this paper, single-phase micronano-structure 304 austenitic stainless steel was prepared by adding excess Fe_2O_3 on the basis of aluminothermic reaction, and the effect of rolling temperature on the microstructure and properties of single-phase micro-nano-structure 304 stainless steel was studied. And the effect of annealing time on the microstructure and properties after rolling and its mechanism. The changes of grain size, volume fraction and ferrite volume fraction of nanocrystalline austenite and submicron austenite in stainless steel are analyzed. Based on the results of the study, it is shown that the evolution mechanism of micro / nano structure and its influence on the corresponding mechanical properties. 1. When the excess ratio of Fe_2O_3 increased from 2.5% to 7.5%, the micronano-structural stainless steel XRD showed that the main phase was austenite, which contained a small amount of ferrite. The ferrite content reaches the minimum when the Fe_2O_3 excess is 5%, and a small amount of ferrite is distributed at the grain boundary of cellular austenite. EDS shows that with the increase of Fe_2O_3 excess ratio, the content of ferrite increases with the increase of Fe_2O_3 excess ratio. The content of Al in the alloy decreased first and then increased, but also led to the decrease of the content of other alloying elements, such as Cr,Ni. The content of 2.Fe_2O_3 excess 5% in stainless steel with micro / nano structure was 1000 鈩，
本文编号：2446278
[Abstract]:In this paper, single-phase micronano-structure 304 austenitic stainless steel was prepared by adding excess Fe_2O_3 on the basis of aluminothermic reaction, and the effect of rolling temperature on the microstructure and properties of single-phase micro-nano-structure 304 stainless steel was studied. And the effect of annealing time on the microstructure and properties after rolling and its mechanism. The changes of grain size, volume fraction and ferrite volume fraction of nanocrystalline austenite and submicron austenite in stainless steel are analyzed. Based on the results of the study, it is shown that the evolution mechanism of micro / nano structure and its influence on the corresponding mechanical properties. 1. When the excess ratio of Fe_2O_3 increased from 2.5% to 7.5%, the micronano-structural stainless steel XRD showed that the main phase was austenite, which contained a small amount of ferrite. The ferrite content reaches the minimum when the Fe_2O_3 excess is 5%, and a small amount of ferrite is distributed at the grain boundary of cellular austenite. EDS shows that with the increase of Fe_2O_3 excess ratio, the content of ferrite increases with the increase of Fe_2O_3 excess ratio. The content of Al in the alloy decreased first and then increased, but also led to the decrease of the content of other alloying elements, such as Cr,Ni. The content of 2.Fe_2O_3 excess 5% in stainless steel with micro / nano structure was 1000 鈩，
本文编号：2446278
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