变形速率对普碳钢中形变诱导铁素体相变的影响

针对普通碳素钢(Q235类型),研究在Ae3～Ar3温度区间内采用形变诱导铁素体机制获得超细晶铁素体的数量与变形速率的相互关系。实验在Gleeble 1500热模拟实验机上进行。实验方案为：1000℃保温2min,以10℃／s的速度冷却到变形温度[Ae3(840℃)至Ar3(780℃)],变形量为30％～50％,变形后立即水淬。结果表明,在840℃变形时,随着变形速率的增大,形变诱导铁素体量增多;在780℃变形时,随着变形速率的增大,形变诱导铁素体量减少;而在840-780℃之间变形时,变形速率存在最佳值,在该值下诱导生成的铁素体量最大。     

Nb微合金钢连续冷却过程中铁素体晶粒尺寸的预测

基于相变动力学和热力学原理,讨论了合金元素Nb对铁素体相变的影响,建立了连续冷却过程中Nb微合金钢铁素体晶粒尺寸预测模型,模拟了应变量、轧制温度、冷却速度和固溶Nb含量对铁素体晶粒尺寸的影响,并将模型计算结果和试验结果进行比较,两者吻合良好,表明该模型能够用来预测Nb微合金钢连续冷却过程中铁素体晶粒尺寸。     

热变形和加速冷却对低碳微合金钢组织的影响

利用Gleeble-1500热模拟实验机研究了热变形和加速冷却工艺对3种低碳微合金钢组织演变的影响,结果表明,在再结晶或未再结晶温区实施1道次变形的晶粒细化效果不如2道次形次的效果明显,在再结晶和再结晶温区实施4道次变形可以得到更细的组织,配合较高的冷却速度可以形成部分针状铁素体组织。随着冷却速度的提高,组织变得更细,并且针状铁素体的数量增加。在相近的变形和冷却条件下,碳、锰含量较高的试样具有更细的组织。     

Influence of Controlled Rolling and Cooling Process on the Mechanical Properties of Low Carbon Cold Forging Steel

In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forging steel was investigated.The results show that the faster cooling after the deformation (especially in low temperature rolling conditions) leads to the refinement of the ferrite grain.The specimen exhibits very good mechanical properties owing to the finer ferrite grains.The pearlite morphologies can also affect the mechanical properties of low carbon cold forging steel.The mechanical properties increase with decreasing final cooling temperature within the range from 650℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony.The mechanical properties of the specimens with fast cooling after the conventional rolling are not only better than those of the specimens with slow cooling after low temperature rolling,but also almost similar to those of the specimens with fast cooling after low temperature rolling.It is suggested that fast cooling after high temperature rolling (the conventional rolling) process would be of important industrial value.     

控轧控冷工艺对低碳铌微合金钢组织和性能的影响

用Gleeble-1500热模拟实验机测定了低碳铌微合金钢变形后的连续冷却转变曲线(CCT曲线),并在实验室对该实验钢采用不同的工艺进行了控制轧制和控制冷却的实验.研究了工艺参数对实验钢力学性能和微观组织的影响,分析了低碳铌微合金钢的强韧化机制.热模拟实验结果表明,实验钢在较宽的冷却速度范围(0.5～30 ℃/s)内可以获得贝氏体组织.控轧控冷的实验结果表明,实验钢的组织主要为铁素体和贝氏体.随着终轧温度的降低,组织得到细化,强度提高,但屈强比也随之增加;降低卷取温度使组织中的贝氏体含量略有增加,强度有所提高.初步探讨了贝氏体对实验钢性能的影响,为制定合适的生产工艺制度提供了依据.     

谈微合金化钢的控轧控冷技术

通过查阅大量参考文献,主要综述了控轧控冷技术的原理、特点及控制要素,并分析了控轧控冷对微合金钢的组织与性能的影响。     

热轧低碳钢不同冷却模式下的相变模拟与验证

利用计算机模拟技术，研究了控轧控冷中输出辊道上冷却模式对低碳钢相变的影响。以低碳钢SS400为例，针对鞍钢热轧带钢厂1780生产线，计算了输出辊道上3种不同冷却模式下低碳钢的相变行为，包括铁素体转变开始温度、组成相体积分数随时间的变化以及铁素体体积分数沿带钢长度方向的分布。研究表明，冷却模式对输出辊道上带钢的温度一时间曲线、铁素体转变开始温度及组成相的演化过程影响较大，但对最终组成相的体积分数影响较小。     

Characteristics of Strain-Induced Ferrite in Low Carbon Steel

Itiswellknownthatthestrain inducedtrans formationfromaustenitetoferritecanleadtograinrefinement .Thushighermechanicalpropertiessuchasstrengthandductilitycanbeobtained[1,2 ] .Someresearcheshavebeencarriedoutonthenucleationofstrain inducedferriteinthepastyears .PDHodgsonetalsuggestedthattheaustenitegrainsshouldbeascoarseaspossibletodecreasenucleationatgrainbo undaries[3 ] .PJHurleyetalconsideredthatthecel lularboundaryofdislocationsuppliesthesitesfornu cleationofstrain inducedferrite[4] .Yang…     

应变诱发铁素体相变对低碳钢晶粒细化的影响

研究了在奥氏体低温区变形时显微组织的变化,并测试了其变形抗力。结果表明：在Ar3以上温度变形会产生应变诱发铁素体相变,使变形抗力下降。通过降低变形温度,铁素体晶粒得到细化。     

Formation of Intragranular Ferrite During Isothermal/Thermomechanical Processes in a Medium Carbon V-Ti-N Microalloyed Steel

For a V-Ti-N microalloyed steel with 0.34%C-1.54%Mn,intragranular ferrite (IGF) was obtained in both isothermal austenite decomposition processes and thermomechanical processes simulating the industrial seamless tubing manufacture process.Results show that with decrease of the isothermal temperature in range of 600℃ down to 450℃,not only the morphology of IGF changed from equiaxed to acicular,but also the equiaxed IGF and the acicular IGF were refined.More importantly,it is found that the amount of equiaxed ferrite increased significantly in the thermomechanical process sample water quenched from 550℃ after 800℃ deformation than that in the isothermally treated sample at 550℃ sample without hot deformation.It implies that appropriate controlled deformation with controlled cooling can significantly promote equiaxed IGF formation,and not solely rely on nucleation mechanisms related with inclusions.Hot deformation of austenite without dynamic and complete static recrystallization causes high energy regions,therefore further promotes the nucleation potency of IGF.     

Surface Ferrite Grain Refinement and Mechanical Properties of Low Carbon Steel Plates

Considering the specialities of the steel plate production, the TMCP study has been carried out with Gleeble 2000 tester to explore the possibility of fine grained ferrite in the low carbon steel plates with the chemical composition of C 0.13--0.18, Si 0.12-0.18, Mn 0.50-0. 65, P 0. 010-0. 025, and S 0. 005-0. 028. The plates with thickness of 8. 7 mm in which the ferrite grain size is smaller than 8μm have been produced by special de- formation process in the laboratory. Furthermore, the trial production of special plain carbon steel plates of 16-25 mm in thickness and 2 000- 2 800 mm in width with fine grained ferrite has been successfully carried out in the Shougang Steel Plate Rolling Plant. The ferrite grain size is 5.5-7μm in the surface layers and 9.5-15μm in the central layer respectively. The yield strength is 320- 360 MPa, tensile strength is 440-520 MPa and the elongation is 25%- 34 %. It is very important for the rolling plants to improve the low carbon steel plates＇ mechanical properties. The results show that the ferrite grains in the surface layer can be refined effectively by the appropriate rolling process, and the strength can be also increased.     

高速拉拔低碳钢的表面结构形态、润滑及性能研究

与普线相比,高线拉拔过程中润滑粉吸附不好,影响线材性能。文章研究了控冷工艺、线材表面形态及润滑剂配方对高线低碳钢拉拔过程中润滑粉吸附效果的影响。高线低碳钢拉拔中吐丝温度为930℃时,盘条氧化铁皮中Fe O最厚,润滑粉吸附效果最好,采用延迟冷却,线材表面润滑粉吸附效果好,有利于提高拉丝钢的拉拔性能;轧制吨位在200-600t时,线材的表面状态最有利于润滑粉的吸附;润滑剂中添加30%油性剂,线材表面润滑粉吸附均匀,有利于拉拔过程的润滑。     

微合金高碳硬线钢的研制

通过实验室研究与酒钢现场生产工艺相结合,对微合金高碳钢在中小型转炉条件下的生产技术进行了研究。试验表明,改进工艺后钢中ω（TO）平均降低至0．0038％,显微夹杂物数量降低了78％,大颗粒夹杂物数量降低了65%。铌微合金化处理后高碳钢线材的力学性能得到了改善。酒钢应用新工艺生产了铌微合金高碳硬线钢2980t,拉拔正常且钢丝性能优良。     

中碳钢形变及冷却过程中的组织演变

热模拟单向压缩下,中碳钢形变温度低于Ad3（786℃）点时,析出形变诱导铁素体（DIF）,DIF量随形变温度降低而提高;在低于750℃形变时,DIF量远高于平衡态铁素体含量54％。DIF析出时碳原子高度富集在铁素体晶界和铁素体／奥氏体界面。形变后在低于A1（719℃）温度等温或控冷过程中。过冷奥氏体将发生不同类型的转变：高于Ad3形变试样中,奥氏体转变为铁素体＋片层状珠光体;低于Ad3点但高于Ar3（645℃）点形变时,未转变奥氏体转变为铁素体＋片层状珠光体＋晶界渗碳体;稍高于Ar3点形变时,将获得铁素体＋弥散渗碳体的球化组织。     

控轧控冷工艺条件下Nb-V钢碳氮化物的析出行为

本文通过热模拟实验和电子显微技术等方法,系统地研究了控轧控冷对铌钒钛复合微合金化低碳热轧钢板的铌、钒、钛碳氧化物的析出行为的影响,研究结果对开发高强度船体用钢板具有参考价值。通过研究表明,在奥氏体区和铁素体区都用Ni(C,N）析出,对Nb、V的析出起了诱导作用,并与Nb、V形成复杂的碳氮化物。在铁素体中主要以基体均匀沉淀析出和位错沉淀析出。     

变形晶界对低碳钢显微组织的影响

对不同温度下变形和变形后再加热到奥氏体区的低碳钢SS400的显微组织进行了研究,结果表明：变形使奥氏体和铁素体晶界呈锯齿状,锯齿状的奥氏体晶界优先成为铁素体的形核位置,锯齿状的铁素体晶界有利于铁素体再结晶核心的形成。     

控轧控冷工艺对DH36级船体用结构钢低温韧性的影响

通过合理的化学成分设计,采用不同的控轧控冷工艺,对DH36船板钢在生产试制过程中产生的-40℃纵向冲击功波动较大的现象进行了研究。研究表明,降低Ⅱ阶段的开轧温度,增大未再晶区的变形量（〉60％）,结合合理的控冷工艺,能有效提高DH36级船板钢的综合性能,尤其是钢的低温韧性。     

含铌钢碳氮化物二相粒子在控轧控冷工艺中析出规律

针对含Nb微合金化钢，模拟安钢中板厂现有生产工艺，利用透射电镜技术，研究在试验室条件下，通过对试样进行单道次及多道次金属再结晶区和未再结晶区的控制轧制，探讨控轧控冷工艺对Nb碳氮化物第二相粒子析出规律的影响，并结合安钢轧制工艺现状，提出建议。     

控制轧制和控制冷却技术的新发展

阐述了控轧控冷工艺的机理和工艺特点，介绍了为改善板形而开发的分开的冷却和润滑系统以及动态轧翻工艺、GCr15轴承钢控轧新工艺的热模拟实验结果和低碳贝氏体钢的新发展。指出应积极消化吸收先进的控轧控冷工艺，研制开发出高强、高韧性钢板。     

控轧控冷工艺对低合金高强钢Q460力学性能的影响

通过改变终轧温度及轧后冷却速度,研究了终轧温度及轧后冷却速度对力学性能的影响。研究结果表明：采用轧后加速冷却的方法,可以显著细化Q460的铁素体晶粒,从而提高其强韧性能。当冷速从2℃/s提高到3.86℃/s时,铁素体晶粒直径从11.5μm细化到8.33μm。当冷速达到2.96℃/s以上时,Rel≥475MPa,Rm≥600MPa,屈强比为70%-80%。