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1.
微合金高强度钢连续冷却转变及显微组织研究   总被引:3,自引:0,他引:3  
以国内某厂新型微合金高强度钢的开发研究为背景,在THERMECMASTOR-Z热模拟试验机上对试验钢种进行了不同变形程度、变形速率和冷却速度等工艺条件下的热模拟实验.分析比较了不同变形工艺参数对微合金高强度钢相变及组织的影响.实验结果表明,提高轧后冷却速度使 Ar3温度降低;高温加热抑制相变,变形促进相变;变形速率越大,相变开始温度越高,变形程度越大,相变开始温度越高.增大变形程度和轧后快速冷却有助于铁素体晶粒的细化和减少珠光体的含量.试验钢种的γ+α两相区的温度范围大于130℃.  相似文献   

2.
薄板坯连铸连轧工艺及微合金高强度钢的开发   总被引:11,自引:1,他引:10  
薄板坯连铸连轧工艺的生产流程有别于传统工艺流程。由于连铸板坯没有经过γ→α和α→γ这两个相变过程,因而导致轧前奥氏体晶粒粗大,不利于产品的组织细化和性能提高。另外,因轧前奥氏体中微合金元素的溶解量相对较高,故而轧后的沉淀强化效果较强。通过优化道次变形量,轧制速度,轧制温度,冷却速率和卷取温度等工艺参数可得到综合性能优良的微合金高强度的带钢产品。  相似文献   

3.
以国内某厂新型微合金高强度钢的开发研究为背景,在THERMECMASTOR-Z热模拟试验机上对试验钢种进行加热、保温、冷却的热模拟试验;并利用Zeiss Axioplan2万能金相光学显微镜进行显微组织观察,分析比较了不同冷却速度对微合金高强度钢相变及组织的影响。试验结果表明,随着冷却速度的增大,相变开始温度和相变结束温度均有所下降,铁素体的含量逐渐减少,晶粒明显细化,相变区间也逐渐减小;与此同时,变形促进了相变的发生。  相似文献   

4.
Nb-V-Ti微合金化高强度钢08MnCr连续冷却转变曲线和组织   总被引:1,自引:0,他引:1  
利用ThermecMaster-Z热模拟实验机测定了一种Nb-V-Ti微合金化高强度钢08MnCr(s2)在910~1 200℃不变形(静态)和变形(动态)奥氏体0.05~30℃/s冷速下连续冷却转变(CCT)曲线,并分析和观察了对应的相变及组织.实验结果表明,提高轧后的冷却速度使Ar3降低,导致钢的晶粒进一步细化;冷却速度大于10℃/s开始出现贝氏体转变.提高加热温度时相变温度降低,变形奥氏体相变温度较不变形奥氏体相变温度高.冷速较低时,铁索体晶粒呈多边形;冷速高时,铁素体晶粒多呈尖角形.  相似文献   

5.
本文从提高我国输油、输气管线用热轧板卷的韧性出发,探讨了在热轧宽带钢连轧机上生产低碳高强度微合金X60~X65级管线钢的优化控制轧制与控制冷却工艺制度,研究了热变形过程中变形奥氏体的再结晶规律、轧后冷却过程中相变规律,以及整个加热、轧制、冷却、卷取过程中微合金元素碳、氮化物的固溶与析出行为。结果表明,该实验用钢的合理控轧控冷工艺为:奥氏体化温度为1200℃,粗轧区开轧温度为1150℃,终轧温度为1050℃;精轧区开轧温度为950℃,终轧温度为860℃,轧后冷却速度为15℃/s,卷取温度为550℃。采用上述工艺,宝钢生产的X60~X65级管线钢板的冲击韧性值提高了1倍以上,其综合性能达到或接近日本进口钢板的实物水平。  相似文献   

6.
张迎晖  赵鸿金  康永林 《钢铁》2007,42(3):52-55
采用正交实验的方法在热模拟机上进行了TRIP钢热变形后冷却工艺的优化研究.结果表明,热变形后控制铁素体相变的慢速冷却的速度及控制贝氏体相变的快速冷却的速度对最终组织的组成影响较大;在分析实验数据的基础上,提出了TRIP钢轧后最佳冷却工艺.  相似文献   

7.
热连轧E36船板钢连续冷却相变行为   总被引:1,自引:0,他引:1  
通过热模拟试验机模拟了20 mm E36船板钢(%:0.15C、0.38Si、1.56Mn、0.011P、0.002S、0.04Nb、0.06V、0.02Ti、0.037Als)经1 080℃和830~890℃分别以变形速率1 s-1变形30%的双道次轧制及冷却过程,测得连续冷却转变曲线,并研究终轧温度和轧后冷却速度(5~25℃/s)对该钢相变和组织的影响。结果表明,随着冷却速度的增加,相变开始温度降低,珠光体的体积分数减小,贝氏体的体积分数增大;随着终轧温度的降低,相变开始温度升高;铁素体晶粒随冷却速度的增加和终轧温度的降低而细化。  相似文献   

8.
本文研究了不同终轧温度和不同轧后冷却速度对09V钢在轧后冷却过程小的动态Ar_3,Ar_1点的影响规律。变形使相变温度提高;终轧温度越低 动态Ar_3,Ar_1温度提高的幅度越大;随轧后冷却速度加快,钢的动态Ar_3,Ar_1温度不断降低。  相似文献   

9.
通过热模拟试验.单道次大变形研究SS400钢形变温度、形变量及轧后冷却速度与显微组织的关系;进行了粗轧后不同待温冷却速度的模拟实验.研究精轧之前待温时间对轧后组织的影响;进行了不同开轧温度的两道次压缩实验,考察精轧开轧温度及终轧温度对组织的影响。  相似文献   

10.
通过对3种不同铌、钒含量的低碳钢进行多道次热压缩变形以模拟中厚板的超细晶轧制工艺,考察了显微组织演变过程、微合金元素和变形条件对组织演变的影响。结果表明:变形过程中有部分奥氏体通过形变诱导相变转变为铁素体;变形并快速冷却后得到平均晶粒尺寸为3~6μm的超细晶组织.铌促进、钒抑制形变诱导铁素体相变,铌、钒微合金化均有较好的细化作用,铌的作用优于钒.再结晶温度以上进行的粗轧有利于精轧时形变诱导铁素体的形成;在精轧温度范围内,增加变形道次、降低道次应变率有利于获得细化的显微组织;降低终轧变形温度对组织细化是最有效的.  相似文献   

11.
The transformation behavior of Nb-V micro-alloyed low carbon austenite steel during continuous cooling was investigated through Gleeble-3800 themomechanical simulator and metallographic analysis. The experimental results show that the dynamic CCT diagrams shift to the left and upper compared with the static ones, the begin temperature of A????-Fe transformation is gradually lower with the increase of cooling rate. The high temperature deformation improves Ferrite and Pearlite transformation and decreases Ferrite transformation zone. When the cooling rate is lower, the deformation improves Bainite transformation; when the cooling rate is higher, the deformation restrains Bainite transformation.  相似文献   

12.
摘要:通过热模拟实验,研究了冷却工艺参数对Ti微合金化高强钢组织和硬度的影响。结果表明:当终冷温度为700℃时,随着冷却速度的增大,铁素体和珠光体组织得到了显著细化,实验钢硬度增加;随着终冷温度的降低,多边形铁素体晶粒尺寸呈减小趋势,铁素体和珠光体含量逐渐降低,珠光体片层间距逐渐减小,贝氏体含量增加,相变强化和细晶强化共同作用使得实验钢的硬度逐渐增加;钢中存在少量粗大的TiN和Ti4C2S2粒子,冷却速度由5℃/s增大到30℃/s,TiC粒子的析出数量明显增加,平均尺寸由8.1nm减小到6.7nm;终冷温度由700℃降到600℃,第二相粒子TiC的析出数量逐渐减少,平均析出粒子尺寸由6.7nm减小到5.9nm。研究结果为Ti微合金化高强钢控制冷却工艺的制定奠定了理论基础。  相似文献   

13.
采用热力模拟试验机、光学显微镜、显微硬度计研究了耐蚀钢12CuCrNiV在不同冷却速率下的连续冷却组织转变规律,并绘制其CCT曲线,同时研究了形变温度和冷却速度对耐蚀钢热变形后的组织和硬度的影响规律。结果表明:连续冷却转变情况下,耐腐蚀钢在冷速小于15℃/s时,有铁素体转变;冷速小于1℃/s时,有珠光体转变;冷速在0.5~20℃/s之间时,有贝氏体转变。控制冷速在5~15℃/s可得到铁素体和贝氏体复相组织。随变形温度的降低,试验钢形变过程中形变诱导铁素体相变现象显著,且伴随有M/A岛生成;随冷却速度的增高,形变诱导相变现象减弱,M/A岛数量减少。与连续冷却试验相比较,形变诱导析出现象明显,其硬度增量为40~50HV,形变可使试验钢的析出向更高冷速移动。  相似文献   

14.
 Continuous cooling transformation behaviors of low carbon steels with two Si contents (050% and 135%) were investigated under undeformed and deformed conditions. Effects of Si contents, deformation, and cooling rates on γ transformation start temperature (Ar3), phase microstructures, and hardness were studied. The results show that, in the case of the deformation with the true strain of 04, the length of bainitic ferrite laths is significantly decreased in low Si steel, whereas, the M/A constituent becomes more uniform in high Si steel. An increase in cooling rates lowers the Ar3 greatly. The steel with higher level of Si exhibits higher Ar3, and higher hardness both under undeformed and deformed conditions compared with the steel with a lower Si content. Especially, the influence of Si on Ar3 is dependent on deformation. Such effects are more significant under the undeformed condition. The hardness of both steels increases with the increase of cooling rates, whereas, the deformation involved in both steels reduces the hardness.  相似文献   

15.
The effect of molybdenum on the continuous cooling transformation behavior of the micro-alloyed low carbon steel containing niobium and titanium was investigated by a Gleeble 3800 thermo-mechanical simulator.The phase transformation temperature of the steel at various cooling rates was detected.The microstructure was observed by optical microscope(OM) and scanning electronic microscope(SEM),and its Vickers hardness was tested.Based on these,its dynamic continuous cooling transformation(CCT) diagrams were determined.The results show that the transformation temperature from deformed austenite to acicular ferrite(AF) is decreased when Mo is added,and the formation of pro-eutectoid ferrite(F) and pearlite(P) is either inhabited or postponed.Mo can also enlarge the range of the cooling rate in forming AF,and refine the microstructure effectively.  相似文献   

16.
在实验室利用Gleeble-3500热模拟试验机对3种Nb、V微合金化Q355E热轧H型钢进行了连续冷却转变规律测试,研究了冷却速度对试验钢组织与硬度的影响。结果表明:在冷速为0.5℃/s时,组织中开始出现贝氏体;冷速大于7℃/s时,珠光体转变即终止。在中等冷速下,Nb的加入促进了贝氏体的形成,抑制了铁素体与珠光体的形核;并且Nb的加入使铁素体转变区右移。Cr的加入降低了较高冷速下铁素体与珠光体相变点,并促进了高冷速下马氏体的形成。由于受V析出的影响,含V试验钢在冷速为1℃/s时其硬度曲线有一个"波谷"。3种试验钢的冷速在0.5~3℃/s之间时,试验钢可获得强韧性较好的细小准多边形铁素体、少量珠光体与贝氏体的复合组织。  相似文献   

17.
 采用热膨胀法结合显微金相与硬度检测,在热模拟试验机上测定了1000MPa级低碳微合金高强钢焊接过程中的临界点Ac1和Ac3,绘制出该钢在不同冷却速率下的焊接连续冷却转变曲线(SH-CCT曲线),研究了冷却速率对焊接热影响区粗晶区(CGHAZ)组织和硬度的影响规律,揭示了不同冷却速率下焊接热影响区的相变过程及组织特征,同时获得了奥氏体晶粒平均尺寸随t8/5的变化关系。研究结果表明,在焊接条件下,该钢的奥氏体化温度要比平衡状态下的奥氏体化温度显著升高;该钢在相当宽的冷却速率范围内发生中温转变,获得贝氏体组织;在较快的冷却速率(≥40℃/s)下,焊接热影响区组织以马氏体为主;随着冷却时间t8/5的增加,硬度逐渐下降,最高硬度HV10为425。在试验条件下,奥氏体晶粒粗化程度并不显著。  相似文献   

18.
The effects of controlled rolling on transformation behavior of two powder forged (P/F) microalloyed vanadium steels and a cast microalloyed vanadium steel were investigated. Rolling was carried out in the austenitic range below the recrystallization temperature. Equiaxed grain structures were produced in specimens subjected to different reductions and different cooling rates. The ferrite grain size decreased with increasing deformation and cooling rate. Ferrite nucleated on second phase particles, deformation bands, and on elongated prior austenite grain boundaries; consequently a high fractional ferrite refinement was achieved. Deformation raised the ferrite transformation start temperature while the time to transformation from the roll finish temperature decreased. Cooling rates in the cast steel were higher than in P/F steels for all four cooling media used, and the transformation start temperatures of cast steels were lower than that of P/F steel. Intragranular ferrite nucleation, which played a vital role in grain refinement, increased with cooling rate. Fully bainitic microstructures were formed at higher cooling rates in the cast steel. In the P/F steels inclusions and incompletely closed pores served as sites for ferrite nucleation, often forming a ‘secondary’ ferrite. The rolling schedule reduced the size of large pores and particle surface inclusions and removed interconnected porosity in the P/F steels. Formerly Postgraduate Researcher in the Department of Metallurgy and Materials Science, UMIST/University of Manchester, United Kingdom  相似文献   

19.
The effect of simple strain path changes as well as post-deformation continuous cooling rate during thermomechanical-controlled processing of microalloyed steel was studied using laboratory physical simulation. The phase transformation characteristics were directly analyzed by dilatometry under various cooling rates. The microstructures of the transformation products were characterized quantitatively using EBSD. The results have shown that while strain path changes impose a considerable influence on the hot flow behavior of the austenite, the cooling rate following hot deformation is the determining factor of the phase transformation mechanism and behavior which establishes the final transformation products and subsequent mechanical properties.  相似文献   

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