0.11C-1.27Mn-0.02Nb-0.01Ti微合金钢连铸坯的高温脆化

在Gleeble 2 0 0 0试验机进行了Q345c hq微合金钢 (% ) :0 11C 1 2 7Mn 0 0 2 0P 0 0 0 7S 0 0 4Cu 0 0 2Nb 0 0 1Ti的连铸坯在 6 0 0～ 10 5 0℃、应变速率 5× 10 - 1 s至 5× 10 - 3 s下的高温拉伸试验。结果表明 ,应变速率为 5 0× 10 - 1 s时 ,Q345c hq钢的脆化温度为 70 0℃左右 ,当应变速率降低到 5 0× 10 - 3 s时 ,钢的脆化温度范围扩大到 6 0 0～ 90 0℃。显微组织分析得出 ,70 0℃时在γ晶界形成网状薄膜先共析铁素体 ,成为裂纹源 ,是脆化的主要原因。避免在 6 0 0～ 90 0℃脆化温度区矫直是防止该钢连铸坯产生裂纹的关键措施     

TC27钛合金的热变形行为及加工图

通过Thermecmaster-Z热模拟试验机,对TC27钛合金在变形温度900～1 150℃和应变速率0. 01～10 s~(-1)范围内进行等温恒应变速率热压缩实验,压缩变形量为50%。结果表明,流变应力随应变的增加迅速增大,达到峰值后随应变的增加而减小,最后趋于相对稳定。流变应力随着温度的增加而减小,随着应变速率的增加而增大。TC27钛合金加工图有2个耗散效率峰值区,一个是900℃/0. 01 s~(-1),此区域变形时出现动态回复;另一个峰值区为1 050℃/0. 01 s~(-1),此区域变形时出现再结晶。     

钕对NiAl基共晶合金高温流变行为的影响

 研究了钕对NiAl 28Cr 55Mo 05Hf共晶合金显微组织及高温流变行为的影响。结果表明：NiAl 28Cr 55Mo 05Hf基体合金是由黑色的NiAl相和灰白色的Cr(Mo)相组成的共晶组织，在相界处聚集有白色的Ni2AlHf(Heusler)相，加入稀土钕可细化组织；NiAl 28Cr 55Mo 05Hf(wNd=005%)合金在较高的应变速率(=194×10-2 s-1和=194×10-3 s-1)下，含稀土合金的流变应力大于不含稀土合金的流变应力，而在低应变速率(=194×10-4 s-1)下，这种强化现象消失。幂指数规律和温度补偿的幂指数规律可以很好地描述各种合金的高温压缩流变行为。加入稀土可降低合金的应力指数和变形激活能，这是因为稀土偏聚在相界上，致使相界上的空位浓度发生变化。     

TA32钛合金板材的超塑性性能研究

研究了真空环境中TA32钛合金在950℃,初始变形速率在5.32×10-4~2.08×10-2s-1条件下的超塑性变形行为。结果表明,不同应变速率条件下,板材的流变应力曲线特征和显微组织演变呈现显著不同。在应变速率较低条件下(5.32×10-4 ~3.33×10-3s-1),拉伸真应力-应变曲线呈传统超塑变形的稳态流动特征,变形后的板材中初生α相晶粒尺寸较大;在高应变速率（8.31×10-3 s-1~2.08×10-2 s-1）条件下,拉伸真应力-应变曲线中流变应力增大到峰值后快速单调递减直到断裂,变形后的板材中初生α相发生动态再结晶,晶粒尺寸与低应变速率条件拉伸的板材相比显著细化。在950℃下,TA32钛合金板材均具有超塑性变形能力,超塑性延伸率在145%~519%之间,当应变速率为5.32×10-4s-1时,板材具有最佳的超塑性性能,拉伸延伸率可达519%。断裂区分析发现,TA32钛合金板材的超塑性断裂模式为空洞聚集-连接-长大型断裂。     

Q345含Nb低碳钢CSP轧制时动态再结晶的研究

用Gleeble -1 50 0热模拟试验机模拟研究了包钢生产的含NbQ3 4 5C低碳钢( % :0 0 56C ,1 2 0Mn ,0 . 0 52Nb ,0 . 0 3 3V ,0 .0 1 2Ti,0 0 .0 52N) 52mm连铸坯在CSP(紧凑式带材生产)轧制时的高温变形过程中真应力应变曲线,回归得出动态再结晶数学模型和动态再结晶的临界条件:Z =9.70×1 0 11exp( 2 5εc)和Z =1 .77×1 0 12 exp( 1 5.8εs) ,式中Z- 变形因子,εc -开始发生动态再结晶的临界变形量,εs -发生完全再结晶的临界变形量。利用动态再结晶判定图,避开轧制道次间的部分再结晶区进行轧制,可有效地降低钢板中的混晶组织。     

钒、氮微合金化钢筋的强化机制

研究了钒、氮微合金化钢筋的强化机理。研究结果表明 ,对 0 .11% V - 85× 10 - 6 N的低氮钢 (钒钢 ) ,约 35 .5 %的钒以 V (C,N)形式析出 ,5 6 .4%的钒固溶在基体中。而在 0 .12 % V- 180× 10 - 6 N的高氮钢中 (钒 -氮钢 ) ,V (C,N)析出量成倍增加 ,约 70 %的钒以 V (C,N)形式析出 ,只有 2 0 %的钒固溶于基体。增氮后 ,V (C,N)析出相的平均尺寸由 10 7nm减小至 73.7nm ,且 1～ 10 nm细小质点的质量比由 2 1.1%提高到 32 .2 %。钢中增氮还细化铁素体晶粒尺寸     

新型Ti-6554钛合金热变形行为及热加工图

利用Gleeble-1500热模拟实验机研究了新型Ti-6Cr-5Mo-5V-4Al合金在740～950℃,应变速率0. 01～10. 00 s^-1条件下的热变形行为。通过真应力-真应变曲线分析了合金在高温变形时的应力随温度及应变速率的变化规律,之后对数据进行回归分析得到了合金的本构方程,最后绘制合金的热加工图并结合微观组织观察研究该合金的热变形机制。结果如下:合金的流变应力对温度和应变速率都十分敏感。在相同的应变速率下,随温度升高,流变应力降低;而在相同温度下,应变速率升高,流变应力也升高。计算得到合金的动态激活能Q为246. 551 kJ·mol^-1。高温变形的本构方程为ε=4. 51×10¹⁰[sinh(0. 0058σ)]^{4. 85272}exp(-246551/RT)。根据热加工图可知,两相区变形时,合金在温度740～770℃、应变速率0. 01～0. 03 s^-1的区域内具有最高的功率耗散系数,达到44%,变形机制为动态回复;β单相区变形时,在温度780～890℃、应...     

王兆文

根据阿基米德原理测量了低温铝电解质Na3 AlF6-AlF3 -Al2 O3 (3% ) -CaF2 (3% ) -MgF2(3% ) -NaCl体系的密度 ,通过回归正交设计计算得到了NaCl含量 (B/ % ) ,冰晶石分子比(CR) ,电解温度 (T/℃ )与电解质密度 (ρ)之间关系的回归 :方程 ρ =4 .35 4 - 8.4 6 4× 10 -3 T+1.983(CR) +2 .0 2 3× 10 -2 B - 2 .882× 10 -4T(CR) +4.70 7× 10 -5TB - 1.6 2 8× 10 -2 (CR)B+4.10 9× 10 -6T2 - 3.84 1× 10 -1(CR) 2 - 2 .0 14× 10 -3 B2 以及经简化方程 :ρ =2 .730 5 - 1.2 2 5× 10 -3 T +2 .2 0 4× 10 -1(CR) - 2 .0 14× 10 -3 (B - 8.2 92 ) 2 ,并讨论了NaCl含量对低温铝电解质密度的影响 ,实验结果表明 :氯化钠含量为 12 %、分子比为 1.5时 ,电解质与铝液的相对密度差大于 15 %。     

本钢铁道车辆用LZ50钢车轴坯的研制

本钢采用铁水预处理、12 0t顶底复吹转炉冶炼、LF +RH TB二次精炼、4 8t钢锭 80 0轧机成坯工艺试生产了铁道车辆用LZ5 0钢 (% :0 4 7～ 0 5 5C ,0 17～ 0 4 0Si,0 6 0～ 0 90Mn) 2 30mm× 2 30mm车轴坯。LZ5 0钢材中氢含量为 (0 5～ 0 7)× 10 -6,氧 (9～ 10 )× 10 -6,氮 (5 5～ 70 )× 10 -6。A +C类非金属夹杂级别为1 0～ 2 5。LZ5 0钢 84 0℃正火处理后的机械性能为σs370～ 385MPa ,σb710～ 735MPa ,δ52 1%～ 2 3%。     

FTSR低碳高强钢连续冷却相变和组织细化

用Gleeble-3500热模拟机研究了低碳钢 (%:0.19C、1.15Mn、0.008Mo、0.002Ti、0.032Als) 85 mm FTSR(薄板坯连铸连轧)铸坯在1 000℃以5 s^-1速率变形40%,然后以5℃/s冷却到900℃并以50 s^-1的速率变形30%,再以1～70℃/s冷却到400℃,空冷的连续相转变和组织。结果表明,冷却速度≤20℃/s时连续冷却转变的组织为铁素体和珠光体;冷却速度达30℃/s时,组织中出现少量粒状贝氏体。随冷却速度增加,晶粒尺寸减小,当冷却速度达10℃/s时,钢中的晶粒尺寸≤10μm,当冷却速度≥20℃/s时,钢中晶粒细化程度减弱。     

碳含量和晶粒尺寸对高碳钢表面脱碳类型和深度的影响

摘要：硬线在加热、轧制等过程中会发生表面脱碳，严重影响工件的性能。通过等温加热实验，研究了加热温度和碳含量对硬线60、70和82B钢表面脱碳层类型和深度的影响，及原始奥氏体晶粒尺寸对弹簧钢60Si2MnA表面脱碳类型和深度的影响。结果表明：保温90min后，60钢在700~750℃时仅存在完全脱碳层，在850~900℃时仅存在部分脱碳层，其完全脱碳层深度随温度增加而逐渐减小，部分脱碳层则相反。70钢仅在850~900℃时存在部分脱碳层。82B钢的脱碳层深度随着温度增加先增加后减少至消失，然后又逐渐增加。硬线在碳含量处于γ单相区时主要发生部分脱碳，且深度随碳含量的升高而增大；碳含量处于α+γ两相区时主要发生完全脱碳，且深度随着碳含量增加先减小后增大。弹簧钢60Si2MnA的完全脱碳层深度随着原始奥氏体晶粒尺寸的增大逐渐减小。     

Effect of carbon content and grain size on structure and depth of surface decarburization of high carbon steel

The surface decarburization of hard wire will occur in the process of heating and rolling, which will seriously affect the performance of workpiece. The effects of holding temperature and carbon content on the type and depth of decarburized layer on hard wire 60, 70 and 82B steel were studied by isothermal heating experiment. The effects of crystallite dimensions of original austenite on decarburization depth of spring steel 60Si2MnA were analyzed. The results show that there is only a complete decarburization layer of 60 steel at 700-750℃ after heating at different temperatures for 90min. There is only a partial decarburization layer at 750-850℃. The depth of decarburized layer decreases gradually with the increase of temperature, and there is only a partial decarburization layer at 850-900℃. The depth of complete decarburization layer decreases gradually with the increase of temperature, and the depth of partial decarburization layer increases gradually with the increase of temperature. The partial decarburization layer of 70 steel only exists at 850-900℃. The depth of complete decarburization layer of 82B steel increases gradually with the increase of temperature, then gradually decreases to zero, at least gradually increases. Only a complete decarburization layer exists at 700℃. There is partial decarburization when the hard wires carbon content is in the γ single phase region, and the depth increases with the increase of carbon content. There is complete decarburization when the carbon content is mainly in the α+γ two phase region, and the depth decreases first and then increases with the increase of carbon content. The depth of the complete decarburization layer of the spring steel 60Si2MnA decreases with the increase of crystallite dimensions of original austenite.     

Recrystallization behavior of twin roll cast low carbon steel strip

The dynamic and static recrystallization behaviors of twin roll cast low carbon steel strip were investigated with an attempt to provide guiding deformation parameters for the on line hot rolling.In order to investigate dynamic recrystallization behavior,as cast strip was reheated and soaked with austenite grain size similar to the width level of the as cast columnar structure.Tensile test was used and the deformation temperature is in the range of 900℃to 1 100℃and strain rates are 0.01 s^-1,0.1 s^-1,1 s^-1.The activation energy and stress exponent were determined as 306kJ/mol and 4.69 respectively.The ratio of critical strain to the peak strain is 0.65,and that of critical stress to the peak stress is 0.92.The dependence of the peak strain on the initial grain size and Zener - Hollomon parameters Z isε_p =9.1×10^-4×D₀^0.48Z^0.13.The kinetics of the dynamic recrystallization and recrystallized grain size was predicted using models published.The as cast coarse austenite were dramatically refined after complete dynamic recrystallization.For static recrystallization,the tensile test was carried out on Gleeble -3500 thermo - mechanical simulator.The deformation temperature is in the range of 800℃to 1 200℃with strain rate 0.01 s^-1 to 1s^-1.The pre strain is fixed at 0.04 to 0.12 and the inter-hit delay time varies from 1 s to 3 000 s.The activation energy and Avrami exponent of static recrystallization were determined as 241 kJ/mol and 0.54 respectively.A kinetics model was proposed to describe the static recrystallization kinetics.The predicted results were in good agreement with the experimental results.     

Influence of intercritical annealing temperature on microstructure and mechanical properties of medium Mn TRIP steel

The transformation, microstructure and mechanical properties of the 0. 2C- 5Mn TRIP steel after intercritical annealing were investigated using dilatometer, scanning electronic microscopy (SEM), transmission electron microscopy(TEM), X- ray diffraction (XRD), and tensile testing machine. The phase transformation thermodynamics of the investigated steel after intercritical annealing was calculated by Factsage software and the characteristics of the transformation were discussed. The results show that the reversed austenite content increases with the increasing of the intercritical annealing temperature, the carbon content in reversed austenite firstly increases and then decreases, manganese content in reversed austenite decreases, which results in the decreasing of the thermal stability of reversed austenite. When the intercritical annealing temperature is 700??, an obvious martensitic transformation occurs during the cooling process. With the increasing of intercritical annealing temperature, cementite is gradually dissolved, but it cannot be completely dissolved due to the short transformation time. When the intercritical annealing temperature is 600-675??, the microstructure after intercritical annealing consists of ferrite, cementite and retained austenite. When the intercritical annealing temperature is 700??, the microstructure after intercritical annealing consists of ferrite, retained austenite, martensite and a small amount of undissolved cementite. The engineering stress and strain curves of the investigated steel are significantly changed with increasing intercritical annealing temperature. At the same time, the optimal mechanical properties with tensile strength of 1138MPa and total elongation of 23% can be obtained after annealed at 675?? for 3min.     

铸轧AZ31镁合金的高温拉伸性能

研究了铸轧AZ31镁合金的高温拉伸性能和变形机制.在300~450℃条件下,分别以恒定拉伸速率10-3 s-1和10-2 s-1进行拉伸至失效试验,在真实应变率为2×10-4~2×10-2 s-1的范围内进行变应变率拉伸试验.当拉伸速率为10-2s-1时,试样在400℃和450℃的延伸率均超过100%;当拉伸速率为10-3 s-1时,试样在400℃和450℃的延伸率均超过200%,该条件下的应力指数n≈3,蠕变激活能Q=148.77 kJ·mol-1,变形机制为溶质牵制位错蠕变和晶界滑移的协调机制.通过光学金相显微镜和扫描电子显微镜观察显示试样断口处存在由于发生动态再结晶和晶粒长大而形成的粗大晶粒,断裂形式为空洞长大并连接导致的韧性断裂.      

高应变速率平面压缩00Cr22Ni5Mo3N双相钢的变形抗力和组织变化

采用Gleeble 3800模拟试验机对锻态00Cr22Ni5M03N双相不锈钢进行900～1200℃,应变速率为10 s^-1和50 s^-1的平面应变试验。结果表明,双相钢的峰值变形抗力随变形温度升高急剧降低,并且当应变速率由10 s^-1提高到50 s^-1时双相钢的峰值应力提高40～60 MPa;在1 000～1200℃变形,钢中铁素体组织发生动态回复和再结晶,奥氏体通过位错的聚集、亚晶界形成发生部分软化。     

0.75C共析钢压缩变形时的组织演变

通过Gleeble 2000和1500热模拟试验机,研究了0.75C共析钢珠光体和过冷奥氏体在压缩变形过程 中的组织演变。试验结果表明,试样以10℃/s加热至700 ℃ 3 min进行60%压缩变形,钢中珠光体片层发生断裂、 破碎;试样加热至1150℃1 min奥氏体化后以20℃/s冷却至700 ℃,压缩变形60%,在变形作用下,钢中部分过冷奥氏体转变成细片层珠光体。     

碳含量对淬火碳钢温变形流变行为的影响

目前关于变形温度、应变速率等因素对流变应力的影响有大量的研究报道,而对温变形条件下碳含量的增加对流变应力的影响规律还缺乏系统研究.基于此开展起始组织为马氏体的不同淬火碳钢温变形流变行为研究.结果表明,在较低温度和较高应变速率(600℃,0.1～1s-1)下,流变应力随碳含量的增加而增大;在较高温度和较低应变速率下(700℃,0.01～0.001 s-1),流变应力在高碳范围内呈下降趋势.碳的质量分数低于0.78％时,淬火碳钢温变形激活能随碳含量的增加而降低;碳的质量分数高于0.78％时,淬火碳钢温变形激活能随碳含量的增加而增加.在相同变形条件下,能量耗散效率最大值随着碳含量的增加呈增大趋势.     

不同硼含量微合金钢的连续冷却相变行为

 利用热模拟试验技术对实验室制备的含硼微合金钢连续冷却转变形为进行了试验研究,利用光学显微镜研究冷却速度、变形对试验钢显微组织的影响,探讨了硼对转变行为的影响规律。结果表明：适量硼延缓多边形铁素体生成,有利于获得贝氏体组织;无硼及wB=00020%时,分别在1~25及05~25℃/s的冷速都能得到贝氏体组织;wB=00030%时,冷速在2℃/s 以上能得到贝氏体组织;与未变形相比,变形导致试验钢贝氏体冷速区间变窄。在同一冷速下,随硼含量增加贝氏体开始转变温度先降低再升高,显微硬度随硼含量增加先增加而后降低。     

热回复过程高强耐候钢Q450NQR1的高温力学性能

在热回复条件下,采用Gleeble-1500D热/力模拟实验机,研究测试了高强耐候钢Q450NQR1(/%:0.05～0.10C、0.30～0.50Si、0.80～1.00Mn、≤0.020P、≤0.008S、0.20～0.40Cu、0.15～0.35Ni、0.40～0.60Cr)200mm×1 350 mm铸坯试样在700～1 000℃,热拉伸应变率5×10^-3 s^-1时的强度、塑性模量和断面收缩率。结果表明,随温度下降铸坯塑性模量(硬化系数)和强度增加,800℃时铸坯的强度随温度的变化速率出现明显转变;925～700℃时铸坯断面收缩率≤60%;为保证铸坯质量,在矫直过程铸坯表面温度应≥950℃。