热处理温度对热镀锌双相钢组织和性能的影响

对不同温度热处理的两种热镀锌双相钢的组织和性能进行了测试,研究了热处理温度对热镀锌双相钢组织和性能的影响,结果表明:在780 ℃热处理时,组织中存在一定比例的珠光体组织,当热处理温度在800 ℃以上时,组织为铁素体 马氏体.热镀锌双相钢的屈服强度随热处理温度的升高而降低,当热处理温度从780 ℃上升到800 ℃时,屈服强度急剧下降.屈强比随热处理温度的升高而降低,当热处理温度从780 ℃上升到800 ℃时,屈强比急剧下降.     

连续退火工艺对冷轧热镀锌双相钢780DP性能的影响

研究了冷轧连续退火过程中退火温度和缓冷段温度对冷轧热镀锌双相钢780DP组织与性能的影响。结果表明,通过调整退火工艺,可以得到强韧性能配合较好的铁素体—马氏体双相钢组织;在一定的温度范围内,随着退火温度和缓冷温度的升高,双相钢780DP抗拉强度有不同程度的下降,而延伸率有所上升,缓冷温度在600℃左右可以得到较理想的实物性能。     

冷轧热镀锌双相钢退火过程中组织演变实验研究

利用OM、SEM、TEM等技术分析了实验钢冷轧组织在热镀锌退火过程中的再结晶与相变规律,研究了460℃左右保温对双相钢显微组织的影响。实验结果表明:在热镀锌退火初期的加热过程中,在680~780℃大量进行再结晶,加热速度较高(10℃/s)会使再结晶进入双相区,与相变并存。在双相区保温时,奥氏体首先在破碎的碳化物处形成,奥氏体量不断增加。460℃保温时,由于处于贝氏体转变区,产生贝氏体组织,马氏体减少,导致强度的下降,对材料力学性能造成不良影响。     

退火温度和平整对冷轧热镀锌双相钢组织和性能的影响

本文在实验室试制了高强度冷轧热镀锌用双相钢,探讨了不同的退火温度和平整工艺对双相钢力学性能和组织的影响规律.研究表明:退火温度在800℃以上时,试制的低硅C-Mn-Cr系双相钢才能得到由铁素体和马氏体组成的性能优良的双相钢.平整工艺显著提高双相钢的屈服强度和屈强比,降低双相钢的延伸率,平整率小于1%时,有利于工业上得到综合性能良好的双相钢.     

冷轧双相钢DP800生产工艺及性能研究

探讨了800 MPa级冷轧双相钢的成分体系、冷却处理工艺、组织及性能;研究了退火温度、冷却速率对双相钢性能的影响,分析了双相钢的强化机理,并且优化了退火工艺参数。结果表明,冶炼过程采用C-Si-Mn-Cr-V成分体系,轧制过程采用650℃±20℃的中温卷取,连续退火过程中快冷段投入高氢(H2含量20%)冷却,冷速达到42~50℃/s,能够得到由铁素体和马氏体组成的冷轧双相钢DP800,综合力学性能优良。     

基于淬火回火的热镀锌退火工艺对双相钢组织性能的影响

提出了基于淬火回火的双相钢热镀锌退火工艺,并进行试验研究了该工艺对双相钢显微组织和力学性能的影响。结果表明,随着热镀锌或/及合金化时间的延长,材料的强度下降、塑性升高,相对于热镀锌退火,热镀锌合金化退火的温度更高、时间更长,因此双相钢的强度下降更明显;微合金元素铌延迟回火时马氏体中固溶碳的析出并延迟马氏体的回复再结晶过程,可以提高双相钢的回火稳定性,从而改善热镀锌双相钢的力学性能。     

超高强度冷轧双相钢组织与性能

在Gleeble-3500热模拟试验机上进行冷轧超高强度双相钢的连续退火工艺研究,利用光学显微镜、扫描电镜、透射电镜和拉伸试验研究了连续退火过程中各个参数对1000MPa级冷轧双相钢组织性能的影响.结果表明:试验用钢在退火温度800℃下保温80s,可以得到抗拉强度为1030MPa、延伸率为14%超高强双相钢;随着退火温度的升高,屈服强度和抗拉强度降低.当退火温度为830℃时,显微组织中粒状的非马氏体组织明显增多.过时效温度低于300℃时,屈服强度和抗拉强度变化不大;当过时效温度超过300℃时,抗拉强度急剧下降,屈服强度先降低后升高,在过时效温度为360℃时开始出现屈服平台.     

工艺参数对800 MPa热镀锌双相钢组织性能的影响

 在实验室试制了低Si 的C Mn Cr Mo系的800 MPa级冷轧热镀锌双相钢,研究了卷取温度、退火温度、退火时间等工艺参数对双相钢微观组织和力学性能的影响。试验结果表明：试验用钢在820~850 ℃退火,保温100 s以上,抗拉强度可以达到800 MPa级以上。随着退火温度的升高,强度升高,但综合性能以退火温度为820 ℃时为最佳。在820 ℃退火时,随着保温时间的增加,双相钢的强度显著增加,当保温时间超过100 s以后,强度增加缓慢。690 ℃高温卷取有利于获得最终力学性能良好的双相钢组织。     

热镀锌双相钢热轧工艺制度研究

研究了热轧工艺对热镀锌双相钢组织与性能的影响。结果表明,通过调整热轧工艺,可以得到强韧性能配合较好的组织均匀的铁素体-马氏体双相钢。在一定的温度范围内,随着终轧温度和卷取温度的升高,双相钢的屈服强度和抗拉强度有不同程度的下降,而延伸率有所上升。高温卷取易导致热轧基板晶粒粗大并出现带状组织,通过降低卷取温度可有效提高热轧基板组织的均匀性,使热轧基板的晶粒细腻均匀,从而改善热轧带状组织。     

热镀锌双相钢的发展和应用

简要介绍了热镀锌和双相钢的发展历程,说明了发展热镀锌双相钢的必要性。介绍了国内外的热镀锌双相钢的生产和应用情况。     

冷却工艺对Si-Mn系热轧双相钢组织和性能的影响

通过热轧试验研究了3种冷却工艺对传统成分Si-Mn系热轧双相钢组织及性能的影响。试验结果表明：在3种冷却工艺条件下,试验钢的最终组织为铁素体和马氏体双相组织。当终轧后采用空冷＋超快冷的冷却工艺时,钢板的屈强比最低,伸长率和n值最大,晶粒尺寸较大,但强度相对最小;当终轧后采用层流冷却＋空冷＋超快冷的冷却工艺时,钢板的晶粒...     

连续退火温度对高硅双相钢组织及性能影响

 用连续退火模拟试验机,在实验室试制了冷轧高硅DP590,并通过扫描电镜、EBSD、透射电镜和力学性能测试研究了不同退火温度（735~835℃）对其组织和力学性能的影响。结果表明：退火温度对高硅双相钢强度和塑性有重要的影响,当退火温度为785℃时,材料获得良好的综合力学性能。不同温度退火后得到的组织均为铁素体和均匀分布在其晶界上的岛状马氏体;利用EBSD技术清晰地观察到离散分布于铁素体和马氏体晶界处的残余奥氏体。运用透射电镜观察到马氏体周围的位错线及位错团,这是双相钢连续屈服特性的重要保障。     

锰对热轧态双相钢显微组织和力学性能的影响

用薄晶体透射电镜研究锰对热轧空冷后低碳Si-Mn双相钢的组织和力学性能的影响。实验结果表明:钢中锰含量为1.79%时,显微组织中出现珠光体。拉伸工程应力-应变曲线有明显物理屈服延伸。钢中锰含量越少、珠光体量越多时,应力-应变曲线上屈服平台越长。锰含量大于2.09%时,轧态组织中不再出现非马氏体型转变产物珠光体。轧态组织中的马氏体岛区,由几个微区组成。这些微区分别为内孪晶马氏体区和位错板条马氏体区。     

Effects of Heat Treatment Process Parameters on Microstructure and Mechanical Properties of DP440Cold Rolled Strip

In order to optimize the production process, improve the production efficiency and accelerate the development and application of the domestic dual-phase steel, the effects of heat treatment process parameters on microstructure and mechanical properties of DP440 cold rolled strip were studied by the CAS-300 simulated continuous annealing equipment. When the heating rate increased from 5 to 100 ℃/s, both the tensile strength and yield strength increased because of the decreased grain size. When the intercritical annealing temperature increased from 780 to 850 ℃, the martensite content decreased so that the tensile strength decreased first, then increased, and the yield strength increased. When the rapid cooling rate increased from 25 to 100 ℃/s, because the martensite content increased, the tensile strength increased, while the yield strength decreased. When the overaging temperature increased from 260 to 400 ℃, the tensile strength decreased, while the yield strength increased. When the overaging time increased from 240 to 480 s, the tensile strength decreased a little, while the yield strength increased a little.     

Microstructure and Properties of 980MPa UltrafineGrained Cold Rolled Dual-Phase Steels

Two kinds of 980MPa grade cold rolled dual phase steels have been developed by designing C-Si-Mn and C-Si-Mn-Nb alloy systems.The microstructure of martensite in Nb-free steel is consisted of lath martensite and twined martensite with the volume fraction of 67%.However,the main hard phase in Nb-containing one is twined martensit with the volume percent of 59%.The size of martensite islands in Nb-containing steel is from 1μm to 3μm,and the size of NbC precipitates is from 15nm to 40nm.As to Nb-containing steel,the yield strength,tensile strength,yield ratio and elongation are 501MPa,1035MPa,0.48 and 17.5% respectively.Futhermore,Nb-containing steel has higher working hardening rate value above the critical strain 6.5%.And it decreases slowly with increasing the strain.This is mainly because of ultrafine grain size and nano-precipitates in ferrite,which improves the compatibility of phases and reduces the stress concentration at the phase interface.     

Relationship Among Microstructure and Properties and Heat Treatment Process of Ultra-High Strength X120 Pipeline Steel

 The variation of heat treatments including directed quenching and tempering off-line after controlled rolling (DQT) and quenching off-line and tempering off-line after controlled rolling (RQT) with microstructure and mechanical properties of a low-carbon microalloyed steel was compared and analyzed. For DQT, the quenched steel was obviously banded microstructure, with increasing tempering temperature, lath martensite coarsened, the cusp carbide precipitated at grain boundaries, the yield strength fluctuated slightly, and the fracture-separation was obvious. The impact toughness was better in the steel tempered at 500 ℃ for 1 h. In RQT, with increasing tempering temperature, lath martensite degenerated, intragranular and intergranular finer precipitations with smaller than 30 nm precipitated and grew up and were distributed dispersedly, the stripe-like carbides were distributed at grain boundaries, and the yield strength and tensile strengthen decreased obviously. The impact toughness of RQT process was much better than that of DQT process, and the comprehensive mechanical properties were better for the steel tempered at 500 ℃ for 1 h of RQT process.     

液压缸筒用热处理双相钢管研究

研究了液压缸筒用热处理双相钢管的力学性能和爆破性能。试验结果表明:热处理双相钢管经精密冷拔后制作液压缸筒,强度高,韧性好,爆破压力也高,并且生产工艺简单,成本低。它可代替调质钢管用作煤矿液压支柱油缸等液压缸筒。     

Effect of Heat Treatment Process on Properties of 1000 MPa Ultra-High Strength Steel

 Two types of steel, C-Mn-Cr-Mo-B microalloyed steel and C-Mn-Mo-Nb-Cu-B microalloyed steel, are designed to develop 1000 MPa ultra-high strength steel. Two kinds of processes, thermomechanical controlled process (TMCP) combined with traditional off-line quenching and tempering (QT) process versus controlled rolling process (CR) combined with direct quenching and tempering (DQ+T) process, are applied. The effect of heat treatment processing mode on the microstructure and mechanical properties is studied. The relationship between microstructure and mechanical properties is investigated by SEM and TEM. After tempering at 450 to 550 ℃ for 1 h, the steel produced by TMCP+QT process shows combination of excellent strength and low temperature toughness. The yield strength is above 1000 MPa, elongation above 15% and impact energy at -40 ℃ more than 30 J. After tempering at 450 ℃, a large number of ε-Cu particles precipitated in C-Mn-Mo-Nb-Cu-B steel produced by CR+DQ+T process lead to a significant increase in yield strength. And after tempering at 500 to 600 ℃, the yield strength of the steel is further improved to 1030 MPa because of precipitates, such as nitride or carbide of niobium, carbide of molybedenum and vanadium. When the tempering temperature is increased above 620 ℃, the yield strength is still higher than 1000 MPa and elongation is above 20% and impact energy at -40 ℃ is more than 35 J. After tempering at above 500 ℃, the toughness of the steel treated by TMCP+QT process is superior to that of steel by CR+DQ+T process.     

590MPa级冷轧双相钢组织与性能研究

实验室进行了590 MPa级冷轧双相钢研制,研究了化学成分、轧制工艺和连续退火工艺,进行了力学性能测定和显微组织分析,结合试验结果分析了平整延伸率对钢带力学性能的影响。结果表明,试制的冷轧双相钢经820℃保温,缓冷至680℃,以> 30℃/s速率冷却至270℃进行过时效处理,平整延伸率为0.8%,得到力学性能优良的冷轧双相钢,试验钢屈服强度、抗拉强度、伸长率分别为376 MPa、652 MPa、1%。