Al-Fe-Sc合金压缩蠕变行为及形貌演变研究

通过压缩蠕变测试及Al-Fe-Sc合金形貌观察，研究了不同压缩蠕变参数对合金蠕变行为及形貌的影响。实验采取压缩蠕变参数：70和90 MPa压应力，90,120和150℃蠕变温度。发现Al-Fe-Sc合金在70 MPa/90,120和150℃条件下，稳态蠕变速率为1.57×10^-7,1.37×10^-5和3.35×10^-6 s^-1，硬度为HV 40.58,HV 35.16和HV 42.32；在90 MPa/90,120和150℃条件下，稳态蠕变速率为1.79×10^-6,1.36×10^-5和7.60×10^-6 s^-1，硬度为HV 45.54,HV 34.46和HV 50.34。样品形貌随温度的升高和压力的增大由各向异性趋向于多种取向，锯齿状晶粒晶界越明显。透射电镜(TEM)图像显示Al₃Sc沉淀相弥散分布在亚晶粒中和亚晶界处，强烈地阻碍了位错和晶界的移动，起到强化力学性能和抑制压蠕变变形的作用。     

预应变量对超低碳烘烤硬化(ULC-BH)钢硬化性能的影响

测定了ULC-BH钢1 mm退火冷轧钢板(/%:0.002C,0.008Si,0.60Mn,0.043P,0.009S,0.031Al,0.071Ti)经2%~10%预应变,170℃20 min烘烤后的烘烤硬化(BH)值,通过内耗实验获得不同应变时效下的内耗谱线,利用X射线衍射技术测定位错密度,研究了Cottrell气团对ULC-BH钢烘烤硬化性能的影响。结果表明,随预应变量增加,ULC-BH钢的BH值增大;随预应变量增加,Snoek峰逐渐降低,而SKK峰逐渐升高;经2%、6%和10%预应变,位错密度增大,分别为3.9×10¹⁰/cm~2,8.4×10¹⁰/cm²和6.8×10¹¹/cm²,相应的Cottrell气团密度逐渐减小。     

去应力退火处理对301不锈钢0.12mm冷轧带钢力学性能的影响

通过连续去应力退火炉将1.2 mm热轧带钢冷轧成0.12 mm SUS301不锈冷轧带钢(/%:0.13C,0.35Si,1.63Mn,0.033P,0.002S,16.54Cr,6.27Ni,0.051N)在单位张力20 MPa下进行250~400℃、退火速度8.0~15.0 m/min的去应力退火对该钢力学性能影响。试验结果表明,去应力退火前301钢0.12 mm冷轧带钢的HV值、抗拉、屈服强度和伸长率分别为498,1 623 MPa,1 498 MPa和6.9%;随退火温度升高,301钢冷轧带钢的强度和硬度增加,同时伸长率下降,在给定的温度下,随退火速度的增加该冷轧带钢的伸长率增加。在400℃8.0~12.5m/min退火时,因产生马氏体相和位错的攀移,冷轧带钢的HV硬度值≥525,抗拉强度和屈服强度分别为1 771.7~1 790.0 MPa和1 566.7~1 623.3 MPa。     

氮含量对U71Mn高速钢轨力学性能的影响

重轨U71Mn钢(%:0.66～0.76C、0.15～0.35Si、1.10～1.40Mn、≤0.030P、≤0.030S)的冶金工艺流程为100 t转炉-LF(VD)-280 mm×380 mm连铸。研究了转炉至中间包各工序[N]及影响因素,氮含量对钢轨力学性能的影响。结果表明,随钢中氮含量由54×10^-6增加至94×10^-6,钢轨的断裂韧性由34.7～38.1 MPa m1/2降至28.1～31.5 MPa m^1/2。LF精炼时将增碳剂由沥青焦改为无烟煤时,钢中氮含量可控制≤64×10^-6,平均氮含量为50.9×10^-6。     

终轧温度对中锰马氏体NM500钢再加热后组织性能的影响

中锰马氏体耐磨钢具有低成本、高强度、高硬度和高耐磨性等特点，在煤炭采运、水泥搅拌和轨道交通等领域具有广阔的应用前景。利用金相显微镜、扫描电子显微镜和透射电子显微镜等设备，以中锰马氏体NM500钢为研究对象，研究了终轧温度对其热处理后组织和力学性能的影响。研究结果表明，与热轧态试样相比，经850℃保温1 h热处理后，试验钢的原始奥氏体晶粒明显细化，相变后的马氏体组织更加细小，低温冲击韧性大幅提升，且较低的终轧温度使得基体中缺陷密度增加，V(C,N)的数量增大，粒径减小，更有利于再加热过程中奥氏体晶粒的细化。当终轧温度由900℃降低至700℃时，经再加热后，试验钢的原始奥氏体晶粒尺寸由10.50μm细化至5.02μm,马氏体的板条块尺寸由1.37μm减小至1.06μm,位错密度由1.05×10¹⁵ m^-2增加至1.51×10¹⁵ m^-2。马氏体多级组织的细化以及位错密度的增加，显著提升了细晶强化增量和位错强化增量，使得试验钢的抗拉强度、屈服强度和硬度分别增加至1 860 MPa、1 084 MPa和54...     

弹簧钢60Si2Mn大方坯凝固组织的数值模拟

运用ProCAST软件的CAFE模块对60Si2Mn弹簧钢325 mm×280 mm连铸坯的凝固组织进行模拟,研究了钢水过热度和二冷强度对铸坯凝固组织的影响。结果表明,浇钢过热度从10℃增大到30℃后,铸坯晶粒密度从1.055×10⁶m-2减小到1.520×10⁵m^-2,柱状晶显著发达;浇钢过热度同为20℃时,二冷区采用强冷后,晶粒密度从1.009×10⁶m^-2增加到1.083×10⁶m^-2,等轴晶率增大5%。     

铜改性碳纳米管增强银基复合材料的力学性能和摩擦磨损性能

分别添加2%(体积分数)的多壁碳纳米管(carbon nanotubes,CNTs)和表面镀Cu改性后的碳纳米管(Cu@CNTs)作为增强相,采用热压法制备Ag基复合材料,研究CNTs的表面改性对银基复合材料力学性能和摩擦磨损性能的影响。结果表明,Ag-2Cu@CNTs复合材料中的CNTs团簇减少,由内到外形成Ag到Cu再到CNTs逐层包裹的结构,力学性能优异,硬度(HV)达到105.6,抗拉强度为248.5 MPa,比纯银分别提高30.05%和127.98%;与纯银相比,Ag-2Cu@CNTs材料具有优良的摩擦磨损性能,平均摩擦因数由0.86降至0.28,体积磨损率从88.54×10^?4 mm³/(N·m)降至3.96×10^?4 mm³/(N·m)。     

热处理对Ti90合金冷轧管材组织与力学性能的影响

采用LD60三辊冷轧机制备出规格分别为?50 mm×6 mm×L和?67 mm×10 mm×L的Ti90合金管材,研究了退火温度对管材显微组织及力学性能的影响。结果表明：冷轧态Ti90合金管材的显微组织由扭折排列的α集束构成,经750℃退火后形成α集束分布均匀的网篮组织,经930℃退火后形成双态组织;退火温度对管材的组织特征影响较大,而轧制变形量仅对管材的β晶粒尺寸有一定影响;随着退火温度的升高,Ti90合金管材的室温抗拉强度和-10℃低温冲击韧性先降低后升高,延伸率变化不明显,且在930℃退火后综合性能最优。     

卷取温度和冷轧压下率对高强度IF钢力学性能的影响

以不同卷取温度(分别为670℃和710℃)工业生产的高强度IF钢热轧板为研究材料,进行了不同冷轧压下率(分别为55%、65%、75%和85%)的实验室冷轧试验,结合连续热镀锌线的工艺特点进行了盐浴退火试验,采用金相和力学性能测试方法,研究了热轧卷取温度和冷轧压下率对高强度IF钢力学性能的影响。结果表明,较低温度卷取时,热轧卷晶粒尺寸较细,冷轧退火态晶粒尺寸相对较粗,rm值相对较低。冷轧退火态仍具有较细小的晶粒,但屈服强度明显降低,这与间隙碳原子在退火过程通过NbC粗化被大量清除有关。卷取温度对试验钢冷轧退火态的强度、断后伸长率和nm值几乎没有影响。随着冷轧压下率从55%增加到75%时,退火后铁素体晶粒尺寸变化不明显,当冷轧压下率进一步增加到85%时,铁素体晶粒尺寸有所减小。冷轧压下率对强度和断后伸长率影响较小,对nm值没有影响,而rm值随着冷轧压下率的提高而提高。     

35 t三流不对称中间包流场的物理数学模拟和应用

以钢厂三流不对称GCr15钢320 mm×480 mm方坯连铸35 t中间包为研究原型,采用1:3水模型试验和数值模拟相结合的方法研究不同控流装置对中间包内流场的影响,优化中间包内流场,并得到最优的导流墙结构。结果表明,原型中间包各水口滞止时间很小,死区比例达到39.68%;增加优化后的Y型导流墙后,滞止时间增大了29.51 s,死区比例减小了15.54%,且各水口一致性较好。通过GCr15轴承钢现场试验发现,中间包优化后钢水T[O]由优化前的19.3×10^-6~26.3×10^-6平均值22.7×10^-6降低至9.5×10^-6~17.2×10^-6,平均12.3×10^-6;铸坯中夹杂物由12.0~15.3个/mm²降低到6.8~8.4个/mm²,>1.25μm夹杂物明显降低。     

深冲用超低碳冷轧带钢铁素体区热轧的现场试验

研究和对比了经1 880 mm热轧机组在奥氏体区(945～848℃)和铁素体区(803～755℃)热精轧,卷取温度700℃以及73%压下率冷轧的3.0 mm超低碳带钢(%:0.008C、0.029Als、0.000 8B、0.001 4N)退火后的组织和性能。结果表明,与奥氏体区轧制比较,热轧采用铁素体区轧制的710℃退火后冷轧带钢具有较高的伸长率、塑性应变比(r值)和应变硬化指数(n),因而具有较好的深冲性能。     

轧制变形对 F-M 双相钢 0.05C-2.8Mn-4.2Ni-2Al- 1.2Mo-1.9Cu晶粒细化的影响

借助EBSD场发射扫描电子显微镜,研究了轧制变形及热处理后的铁素体/马氏体双相钢0.05C-2.8Mn4.2Ni-2Al-1.2Mo-1.9Cu显微组织演变及力学性能。结果表明,经900℃30%+780℃75%变形,500℃退火的F-M钢晶粒尺寸0.97μm,屈服、抗拉强度和延伸率分别为876 MPa,976 MPa和15.2%,经900℃30%+780℃50%变形,500℃退火的F-M钢晶粒尺寸1.54μm,屈服、抗拉强度和延伸率分别为801 MPa,895 MPa和19.4%。由轧制变形导致的晶粒细化、小角度晶界增多,是提高实验钢强度的主要原因。然而,较大的轧制变形量也使过多的小角度晶界阻碍位错运动,从而导致实验钢在塑性变形过程中,延展性略差。     

HRB335热轧带肋钢筋轧后双线穿水冷却技术的应用

针对轧机产量提高后冷床冷却能力不足的问题,安装了轧后棒材穿水冷却装置。生产结果表明,HRB335Φ16 mm热轧带肋钢筋(/%:0.20C、0.20～0.40Si、0.4～1.2Mn),原终轧速度10.5～11.0 m/s,钢材至冷床温度1020～1050℃,钢筋的屈服、抗拉强度和伸长率分别为342 MPa、520 MPa和16.5%;使用穿水系统后终轧速度提高至11.5～12.0 m/s,钢材至冷床的温度降至880～900℃,通过冷床后降至260℃,钢筋的屈服、抗拉强度和伸长率分别为360 MPa,556 MPa和16.9%,生产率提高3%～5%。     

平整工艺对冷轧780MPa级双相钢力学性能的影响

采用不同的平整工艺对连续退火780 MPa级别的冷轧双相钢进行平整试验,研究了平整伸长率对连续退火780 MPa级别双相钢力学性能的影响,并建立了平整伸长率与780 MPa级别双相钢力学性能的函数关系模型。研究表明：随着平整伸长率的提高,780 MPa级别双相钢的屈服强度提高,抗拉强度保持不变,同时均匀伸长率和总伸长率均有所下降。     

Effects of Cold Rolling Reduction on Retained Austenite Fraction and Mechanical Properties of High-Si TRIP Steel

 Transformation-induced plasticity-aided steel ［TRIP steel (0. 4C-1. 5Si-1. 5Mn)］ was rolled at room temperature to different thickness reductions (0, 4%, 10%, 20%, 40%, and 60%). The mechanical properties, microstructure and austenite fractions of the rolled samples were measured by tensile test, electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) for each rolling. The deformation behavior was studied based on the analysis of the mechanical properties and microstructure of steel after tensile deformation, aiming at understanding the effects of cold rolling reduction on the decay behavior of the austenite and the change of mechanical properties of the TRIP steels. It was found that increasing rolling reduction increases the yield stress gradually but decreases the total elongation significantly. It is very interesting that after 10% rolling reduction the yield stress is about 1000 MPa but still with 20% total elongation, which gives an excellent combination of yield strength and ductility. Based on the XRD results, it was revealed that in both rolling and tension the austenite volume fraction monotonically decayed with the increase of rolling strain, but the decaying rate is faster in tension than in rolling, which may be ascribed to the higher temperature in rolled specimens than in the tensioned ones during deformation. Experimental results and theoretical reasoning indicate that the decreasing trend of austenite volume fraction with strain can be formulated by a unique equation.     

Nb-V微合金化0.15 ~ 0.35Mo含量和轧制温度对建筑用耐火钢性能的影响

试验钢采用50 kg中频感应炉熔炼,并轧成13mm钢板。试验了R1-0.15MoNb,R2-0.15MoV,R3-0.35MoNbV,R4-0.35MoNbVB和R5-0.35MoNbVTiB耐火钢的轧制温度（1 010～1 050℃）对该钢性能的影响。结果表明,R3钢（/%:0.04C,1.12Mn,0.32Si,0.018P,0.023S,0.35Cr,0.35Mo,0.025Nb,0.15N）在1030℃轧制后具有最佳的综合性能,即抗拉强度598 MPa、屈服强度514 MPa、延伸率28%、屈强比0.86、600℃回火前后HV硬度值分别为215和204、0℃冲击功124J;600℃的屈服强度355 MPa,屈强比为0.69,满足耐火钢国家标准要求。     

冷轧变形量对304不锈钢力学性能的影响

 研究304奥氏体不锈钢薄板的硬度随冷轧变形量的变化规律,为奥氏体不锈钢薄板工业生产提供指导。同时,采用金相显微镜、维氏硬度测量、X-射线衍射仪和透射电镜研究了不同变形量冷轧对304不锈钢显微组织和机械性能的影响。在室温对0.5mm厚退火板材进行冷轧,使冷轧变形量从10%增加到52%。结果表明,形变诱发马氏体相变是导致304不锈钢冷轧时产生加工硬化的主要原因,冷轧可以显著提高钢的强度和硬度。当冷轧变形至40%时,304不锈钢的维氏硬度是未变形时的2.2倍,屈服强度、抗拉强度分别增大到未变形时的4.2倍（880MPa）和1.8倍（1312MPa）。     

Recrystallization kinetics of an austenitic high-manganese steel subjected to severe plastic deformation

The evolution of the microstructure and the properties of an austenitic high-manganese steel subjected to severe deformation by cold rolling and subsequent recrystallization annealing is investigated. Cold rolling is accompanied by mechanical structural twinning and shear banding. The microhardness and microstructural analysis of annealed samples are used to study the recrystallization kinetics of the high-manganese steel. It is shown that large plastic deformation and subsequent annealing result in rapid development of recrystallization processes and the formation of an ultrafine-grained structure. A completely recrystallized structure with an average grain size of 0.64 μm forms after 30-min annealing at a temperature of 550°C. No significant structural changes are observed when the annealing time increases to 18 h, which indicates stability of the recrystallized microstructure. The steel cold rolled to 90% and annealed at 550°C for 30 min demonstrates very high strength properties: the yield strength and the tensile strength achieve 650 and 850MPa, respectively. The dependence of the strength properties of the steel on the grain size formed after rolling and recrystallization annealing is described by the Hall–Petch relation.     

Deformation Behavior of Fe-36Ni Steel during Cryogenic (123-173 K) Rolling

Microstructural evolution and mechanical properties of cryogenic rolled Fe-36Ni steel were investigated. The annealed Fe-36Ni steel was rolled at cryogenic temperature( 123-173 K) with 20%- 90% rolling reduction in thickness.The deformation process was accompanied by twinning at cryogenic temperature,and the mean thickness of deformation twins was about 200 nm with 20% rolling reduction. When the rolling reduction was above 40%,twinning was suppressed due to the stress concentration in the tested steel. Deformation microstructure of Fe-36Ni steel consisted of both twin boundaries and dislocations by cryogenic rolling( CR),while it only contained dislocations after rolling at room temperature( RT). The tensile strength of Fe-36Ni steel was improved to 930 MPa after 90% reduction at cryogenic temperature,while the tensile strength after 90% reduction at RT was only 760 MPa. More dislocations could be produced as the nucleation sites of recrystallization during CR process.