工艺参数对中Mn-TRIP钢组织和性能的影响
发布时间：2019-02-13 01:22
【摘要】：随着汽车领域的不断发展,除了在汽车安全性上的要求越来越高,节能减耗也逐渐成为一种新的发展趋势,为了实现这个目标,迫切需要开发和应用高强钢与超高强钢。中Mn-TRIP钢作为典型的第三代先进汽车高强钢,开始受到越来越多的关注。本文以中频感应熔炼炉冶炼出的四种不同成分的中Mn-TRIP试验钢为研究对象,通过连续冷却转变、形变热模拟、中试热轧和中间退火等试验,研究了热轧工艺参数和退火工艺参数对中Mn-TRIP钢组织和性能的影响。首先在Gleeble3500热力模拟试验机上对试验钢的连续冷却转变规律进行了研究,得到了对应的连续转变曲线;研究了形变热模拟工艺对试验钢组织和性能的影响。结果表明:马氏体相变在实验的所有冷速条件下都可以发生,随着冷速增加,马氏体含量增加,不同成分的马氏体组织形态存在一定差异;贝氏体相变只有在冷速比较低的情况下才有可能发生;在实验条件下改变形变温度和变形量的低温大变形对试验钢的组织转变影响不大。在此基础上,根据试验钢组织和变形工艺参数之间的关系,确定了试轧工艺参数并开展了中试轧制试验,对不同终轧温度下试验钢组织和性能的变化规律进行了研究,结果表明:成分相同,随着终轧温度降低,原始奥氏体晶粒尺寸减小,形成的马氏体束也较小,板条更细更短,马氏体相变更完全;同时,终轧温度越低,对应的抗拉强度反而越高,延伸率降低;在所有热轧态试验钢中,1-3号试验钢的综合力学性能最佳。中Mn-TRIP钢热轧后必须进行退火处理,以获得更好的强度和塑性的匹配,也可为后续冷轧做好组织准备。因此,本文研究了不同成分的试验钢在退火后组织和性能的变化,发现在不同退火温度下退火10h后,不同成分的试验钢组织中马氏体的数量都有减少,分布也更加均匀,铁素体数量减少,由XRD衍射图谱还可发现退火后出现了一定数量的残余奥氏体;同时,随着退火温度的升高,屈服强度先减小后增大,抗拉强度提高,而断后延伸率降低,当退火温度为620℃时,综合力学性能最佳,强塑积最大可达31.5 GPa·%。
[Abstract]:With the continuous development of automobile field, in addition to the higher and higher requirements of automotive safety, energy saving and consumption reduction has gradually become a new development trend. In order to achieve this goal, it is urgent to develop and apply high-strength steel and ultra-high strength steel. As a typical third generation advanced automobile high strength steel, medium Mn-TRIP steel has been paid more and more attention. In this paper, four kinds of intermediate Mn-TRIP test steels with different compositions from intermediate frequency induction smelting furnace were studied. The experiments were carried out through continuous cooling transformation, deformation thermal simulation, pilot-scale hot rolling and intermediate annealing, etc. The effects of hot rolling process parameters and annealing process parameters on the microstructure and properties of Mn-TRIP steel were studied. At first, the continuous cooling transformation law of test steel was studied on Gleeble3500 thermal simulation machine, and the corresponding continuous transformation curve was obtained, and the effect of deformation thermal simulation technology on the microstructure and properties of test steel was studied. The results show that martensite transformation can take place under all the experimental cooling rates, and with the increase of cooling rate, the content of martensite increases, and the microstructure of martensite with different composition is different to a certain extent. Bainitic transformation can occur only when the cooling rate is low, and the change of deformation temperature and deformation amount at low temperature and large deformation have little effect on the microstructure transformation of the test steel. On this basis, according to the relationship between the microstructure and deformation parameters of the test steel, the parameters of the test rolling process were determined and the rolling tests were carried out. The variation of the microstructure and properties of the tested steel at different finishing rolling temperatures was studied. The results show that the grain size of the original austenite decreases, the martensite beam is smaller, the lath is thinner and shorter, and the martensite phase changes completely with the decrease of the final rolling temperature. At the same time, the lower the final rolling temperature, the higher the tensile strength and the lower the elongation. Among all the hot rolled test steels, 1-3 # test steel has the best comprehensive mechanical properties. Middle Mn-TRIP steel must be annealed after hot rolling in order to obtain a better match of strength and plasticity, and it can also be prepared for subsequent cold rolling. Therefore, the changes of microstructure and properties of different composition test steels after annealing are studied in this paper. It is found that after annealing for 10 h at different annealing temperatures, the number of martensite in different compositions of test steels decreases and the distribution of martensite is more uniform. The number of ferrite is reduced, and a certain amount of retained austenite can be found after annealing by XRD diffraction pattern. At the same time, with the increase of annealing temperature, the yield strength decreases and then increases, and the tensile strength increases, while the elongation at break decreases. When the annealing temperature is 620 鈩，
本文编号：2421022
[Abstract]:With the continuous development of automobile field, in addition to the higher and higher requirements of automotive safety, energy saving and consumption reduction has gradually become a new development trend. In order to achieve this goal, it is urgent to develop and apply high-strength steel and ultra-high strength steel. As a typical third generation advanced automobile high strength steel, medium Mn-TRIP steel has been paid more and more attention. In this paper, four kinds of intermediate Mn-TRIP test steels with different compositions from intermediate frequency induction smelting furnace were studied. The experiments were carried out through continuous cooling transformation, deformation thermal simulation, pilot-scale hot rolling and intermediate annealing, etc. The effects of hot rolling process parameters and annealing process parameters on the microstructure and properties of Mn-TRIP steel were studied. At first, the continuous cooling transformation law of test steel was studied on Gleeble3500 thermal simulation machine, and the corresponding continuous transformation curve was obtained, and the effect of deformation thermal simulation technology on the microstructure and properties of test steel was studied. The results show that martensite transformation can take place under all the experimental cooling rates, and with the increase of cooling rate, the content of martensite increases, and the microstructure of martensite with different composition is different to a certain extent. Bainitic transformation can occur only when the cooling rate is low, and the change of deformation temperature and deformation amount at low temperature and large deformation have little effect on the microstructure transformation of the test steel. On this basis, according to the relationship between the microstructure and deformation parameters of the test steel, the parameters of the test rolling process were determined and the rolling tests were carried out. The variation of the microstructure and properties of the tested steel at different finishing rolling temperatures was studied. The results show that the grain size of the original austenite decreases, the martensite beam is smaller, the lath is thinner and shorter, and the martensite phase changes completely with the decrease of the final rolling temperature. At the same time, the lower the final rolling temperature, the higher the tensile strength and the lower the elongation. Among all the hot rolled test steels, 1-3 # test steel has the best comprehensive mechanical properties. Middle Mn-TRIP steel must be annealed after hot rolling in order to obtain a better match of strength and plasticity, and it can also be prepared for subsequent cold rolling. Therefore, the changes of microstructure and properties of different composition test steels after annealing are studied in this paper. It is found that after annealing for 10 h at different annealing temperatures, the number of martensite in different compositions of test steels decreases and the distribution of martensite is more uniform. The number of ferrite is reduced, and a certain amount of retained austenite can be found after annealing by XRD diffraction pattern. At the same time, with the increase of annealing temperature, the yield strength decreases and then increases, and the tensile strength increases, while the elongation at break decreases. When the annealing temperature is 620 鈩，
本文编号：2421022
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