热轧工艺和合金成分对釉化用钢组织性能影响的研究
发布时间：2019-05-11 08:17
【摘要】：本课题研究了生产热水器内胆所用的低C釉化用钢,因热水器内胆在使用时需承受一定的温度和压力,故对釉化用钢的屈服强度有一定的要求。在实际的釉化烧结过程中,釉化用钢会经历晶粒粗化、相变和溶质扩散等过程,其力学性能也会相应地发生变化,而热轧工艺和合金成分在很大程度上决定了釉化用钢轧制态和釉化烧结后的性能,因此研究热轧工艺和合金成分对釉化用钢组织性能的影响具有重要意义。本文采用实验、有限元模拟和热力学计算相结合的方法,对不同成分和轧制工艺的釉化用钢进行了深入研究,分析讨论了连轧和形变诱导铁素体相变(DSIT)工艺、以及合金元素Si和Mn含量对釉化用钢在釉化烧结前后的力学性能和显微组织的影响,为进一步改进轧制工艺和合金成分提供指导。主要的研究结果如下:与传统的连轧工艺相比较,由DSIT工艺轧制的钢板因经历了反复的形变诱导铁素体相变而获得了较细小的晶粒。但当后三道次开轧温度较高时,由于应变诱导铁素体相变形核的不均匀性以及组织中出现的较多的块状相,使得钢板的轧制态屈服强度与连轧钢板无明显差别,且屈服平台变窄;当控制后三道次开轧温度接近Ar3时,DSIT工艺轧制的钢板的组织均匀性得到改善,屈服强度有一定的提高。经815℃～871℃不同温度的热处理后,连轧钢板的屈服强度出现了明显的下降,降幅在20～30MPa之间;而DSIT轧制的钢板热处理后屈服强度有不同程度的提高。热处理过程中钢板屈服强度的变化与显微组织的演变相对应。有限元模拟结果显示:在轧制初期,钢板表面温度均低于心部温度,随着轧制过程的进行,两者趋于一致。在DSIT轧制过程中,钢板所承受的轧制力更大,温度波动也更为明显。对于不同Si、Mn含量的钢板,Si含量较低的钢板无明显的屈服平台,且组织中存在较多尺寸较大的珠光体相,铁素体晶粒增大;经815℃～871℃热处理后,钢板的拉伸曲线出现了明显的屈服平台,屈服强度增加,但受热处理温度影响较大,热处理温度较高时屈服强度发生下降,可能与高温热处理后钢板显微组织中的珠光体尺寸较大有关。根据热力学计算结果,降低Si含量和增加Mn含量均会使铁素体-奥氏体转变温度降低,保温过程中钢板中的奥氏体量增多,这可能是钢板组织中珠光体形态受热处理温度影响较大的原因。此外,提高Mn含量后,组织中的Mn23C6析出相将会增多,相应地将消耗更多的C原子,使得固溶在铁素体基体中的C减少,间隙原子钉扎位错形成的"柯氏气团"数量也相应减少,这可能是Mn含量较高的钢板在热处理后屈服强度较低的原因。
[Abstract]:In this paper, the low C glazed steel used in the production of inner tank of water heater is studied. Because the inner tank of water heater needs to bear a certain temperature and pressure when it is used, there are certain requirements for the yield strength of glazed steel. In the actual glazing sintering process, the glazed steel will go through the process of grain coarsening, phase transformation and solute diffusion, and its mechanical properties will also change accordingly. The hot rolling process and alloy composition determine the rolling state and properties of glazed steel to a great extent, so it is of great significance to study the effect of hot rolling process and alloy composition on the microstructure and properties of glazed steel. In this paper, the glazed steel with different composition and rolling process has been deeply studied by means of experiment, finite element simulation and thermodynamic calculation, and the (DSIT) process of continuous rolling and deformation induced Ferrite transformation has been analyzed and discussed. The effects of Si and Mn contents on the mechanical properties and microstructure of glazed steel before and after glazing sintering provide guidance for further improvement of rolling process and alloy composition. The main results are as follows: compared with the traditional continuous rolling process, the steel plate rolled by DSIT process has obtained finer grains due to repeated deformation-induced Ferrite phase transformation. However, when the temperature of the last three passes is high, the rolling yield strength of the steel plate is not significantly different from that of the continuous rolling steel plate due to the inhomogeneity of the deformed nucleus of the strain-induced ferrite phase and the appearance of more bulk phases in the microstructure. And the yield platform becomes narrower; When the three-pass rolling temperature is close to Ar3, the microstructure uniformity and yield strength of the steel plate rolled by DSIT process are improved to a certain extent. After heat treatment at different temperatures from 815 鈩，
本文编号：2474334
[Abstract]:In this paper, the low C glazed steel used in the production of inner tank of water heater is studied. Because the inner tank of water heater needs to bear a certain temperature and pressure when it is used, there are certain requirements for the yield strength of glazed steel. In the actual glazing sintering process, the glazed steel will go through the process of grain coarsening, phase transformation and solute diffusion, and its mechanical properties will also change accordingly. The hot rolling process and alloy composition determine the rolling state and properties of glazed steel to a great extent, so it is of great significance to study the effect of hot rolling process and alloy composition on the microstructure and properties of glazed steel. In this paper, the glazed steel with different composition and rolling process has been deeply studied by means of experiment, finite element simulation and thermodynamic calculation, and the (DSIT) process of continuous rolling and deformation induced Ferrite transformation has been analyzed and discussed. The effects of Si and Mn contents on the mechanical properties and microstructure of glazed steel before and after glazing sintering provide guidance for further improvement of rolling process and alloy composition. The main results are as follows: compared with the traditional continuous rolling process, the steel plate rolled by DSIT process has obtained finer grains due to repeated deformation-induced Ferrite phase transformation. However, when the temperature of the last three passes is high, the rolling yield strength of the steel plate is not significantly different from that of the continuous rolling steel plate due to the inhomogeneity of the deformed nucleus of the strain-induced ferrite phase and the appearance of more bulk phases in the microstructure. And the yield platform becomes narrower; When the three-pass rolling temperature is close to Ar3, the microstructure uniformity and yield strength of the steel plate rolled by DSIT process are improved to a certain extent. After heat treatment at different temperatures from 815 鈩，
本文编号：2474334
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