Effect of Thermomechanical Processing on the Microstructure and Mechanical Properties of Nb-Ti-V Microalloyed Steel

The paper presents the results of thermomechanical treatment via forging on the microstructure and mechanical properties of newly obtained microalloyed steel containing 0.28% C, 1.41% Mn, 0.027% Nb, 0.028% Ti, and 0.019% V. The investigated steel is assigned to the production of forged elements for the automotive industry. Conditions of forging using the thermomechanical processing method were developed based on plastometric tests. Continuous and double-hit compression tests were conducted using the Gleeble 3800 thermomechanical simulator. The samples were investigated in a temperature range from 900 to 1100 °C and a strain rate of 1 and 10 s^?1. To determine the recrystallization kinetics of plastically deformed austenite, discontinuous compression tests of samples using the applied deformation were conducted in a temperature range from 900 to 1100 °C with isothermal holding of the specimens between successive deformations for 2-100 s. Observations of the microstructures of thin foils were conducted using a TITAN80-300 FEI transmission electron microscope. The applied thermomechanical treatment allows to obtain a fine-grained microstructure of the austenite during hot-working and production of forged parts. These acquire advantageous mechanical properties and guaranteed crack resistance after controlled cooling from the end plastic deformation temperature and successive tempering. Forgings produced using the thermomechanical treatment method, consecutively subjected to tempering in a temperature range from 550 to 650 °C, reveal values of YS_0.2 which equal from 994 to 892 MPa, UTS from 1084 to 958 MPa, KV from 69 to 109 J, KV^?40 from 55 to 83 J, and a hardness ranging from 360 to 300 HBW.     

形变热处理对Al-Li合金组织和性能的影响

研究了形变热处理对2091型Al-Li合金显微组织和力学性能的影响,结果表明,固溶＋8％变形＋双级时效可以使合金获得良好的强塑性配合。合金中主要强化相δ（Al3Li）适宜的粒度、析出相S’（Al2CuMg）分散沉淀、晶界上平衡相析出量的减少以及δ＇无沉淀析出带（PFZ）的窄化,是合金强塑性改善的主要原因。     

形变热处理对ZK60镁合金组织性能的影响

对ZK60镁合金进行了热挤压、热处理实验,并对挤压态、挤压后T5处理态、挤压后T6处理态试样分别进行了室温拉伸试验,并观察其金相组织.结果表明:铸态ZK60镁合金热挤压后,在晶粒细化同时,有大量细小点状第二相析出,使其综合力学性能明显提高.挤压后直接时效的T5态试样,其抗拉强度比挤压态有所提高,伸长率稍有降低;挤压后经T6处理的试样,抗拉强度和伸长率均比挤压态、挤压+T5态的低.     

Effect of High-Temperature Severe Plastic Deformation on Microstructure and Mechanical Properties of IF Steel

Extensive research work has been carried out on interstitial-free steel to understand its response to deformation; particularly, the behavior during severe plastic deformation (SPD). However, most of these studies were mainly undertaken in the ferritic regime. The present investigation reports the initial results of our attempt to employ accumulative roll bonding (ARB), one of the variants of SPD, at a high temperature (950 °C). A considerable grain refinement has been observed, which may be attributed to the severity of deformation and recrystallisation at high temperatures. Nanoindentation tests have been performed at various stages of ARB process to understand the evolution of mechanical properties.     

退火方式对390MPa级高强IF钢组织及性能的影响

研究了390MPa级高强IF钢在连续退火和罩式退火条件下的组织与性能,结果表明,连续退火和罩式退火后P210P1钢的组织均较纯净,为铁素体组织；与连退卷相比,罩退卷的晶粒尺寸偏小,且晶粒尺寸均匀性较差.连退卷力学性能指标均满足国标要求,而罩退卷的r90°值较低,其余指标与连退卷相当.     

热处理对模具钢组织与力学性能的影响

考察3Cr2Mo型塑料模具钢经200～600℃回火处理后的力学性能和组织形态变化.结果表明,回火处理后,该钢粒状贝氏体组织出现大量针状碳化物和稳定化的不连续条形岛状组成物,发现其有利于提高3Cr2Mo钢的冲击韧度和屈服强度.当在350℃同火处理3 h,可使该钢的屈服强度提高40%,冲击韧度提高60%.     

退火工艺对IF钢显微组织与力学性能的影响

对IF钢板分别进行了模拟连续退火和快速退火,运用EBSD技术对退火钢板的显微组织进行了研究,测试了退火钢板的力学性能,探讨了退火工艺对IF钢显微组织与力学性能的影响。结果表明:与模拟连续退火工艺相比,快速退火工艺使IF钢板晶粒更加细小均匀且同样具有强烈的γ-<111>//ND再结晶织构,但导致IF钢规定非比例延伸强度Rp0.2升高,断后伸长率降低,塑性应变比r90降低。     

时效处理对超高锰钢组织及力学性能的影响

研究了时效处理工艺对超高锰钢的组织及小变形轴向压缩情况下的形变硬化能力的影响.结果表明,适当的时效处理可以提高超高锰钢的形变硬化能力,硬化速率与起始硬度无关.经时效处理的超高锰钢,真应力一真应变分段符合Hollomon方程,具有双n力学行为,小变形即可获得较高形变硬化.     

热处理对超高碳钢组织和性能的影响

采用几种不同的热处理工艺对超高碳钢进行球化处理,并对不同热处理状态下的试样进行了组织观察和力学性能测试分析,探讨了热处理对超高碳钢组织和性能的影响。结果表明,随着碳化物球化率的提高,钢的塑性得到明显改善。经840℃×20min淬火+650℃×3h高温回火处理样品因能获得圆整度高的球状碳化物,而拥有σs=576MPa、σb=835MPa的高强度和δ5=18·4%的良好塑性。经1200℃×4h高温正火+800℃×2h球化退火处理的超高碳钢由于获得的球状碳化物颗粒细小且分布均匀,基体在变形时受到的阻碍作用较弱,故强度较高(σs=622MPa,σb=927MPa),但塑性稍有下降(δ5=16·0%)。经720℃×3·5h退火处理和840℃×20min空冷+720℃×2·5h退火处理的超高碳钢尽管含有一定量的片状碳化物,也能获得高的强度(σs>590MPa,σb>870MPa)和较好的塑性(δ>11%)。     

不同退火工艺下高强IF钢的微观组织和力学性能

以含Nb高强IF钢为研究对象,经热轧、冷轧和模拟连续退火,研究了不同退火工艺下IF钢的微观组织和力学性能。结果表明,冷轧压下率和退火温度一定时,IF钢的晶粒尺寸随退火时间的增加而不断变大。当退火温度为850℃,保温时间为120²40 s时,IF钢的抗拉强度为470 MPa,屈强比为0.60。     

Effect of Heat Treatment on Microstructure and Mechanical Properties of Quenching and Partitioning Steel

In order to investigate the effect of microstructural characterization on the mechanical properties and retained austenite stability, a different type of quenching and partitioning steel(I-QP) through intercritical annealing before the quenching and partitioning process was designed, which can realize lamellar intercritical microstructure compared to the conventional quenching and partitioning(QP) process. The morphology of ferrite and martensite/retained austenite is lamellar in the I-QP steel while it is equiaxed after being heat-treated by conventional QP process. The I-QP steel is proved to have better formability and mechanical properties than conventional QP steel, which is due to the highervolume fraction of retained austenite in the I-QP steel and confirmed by electron backscattering diffraction patterns and X-ray diffraction. Furthermore, the stability of retained austenite in I-QP steel is also higher than that in conventional QP steel, which is investigated by tensile tests and differential scanning calorimetry.     

深冷处理对Cr12钢组织和力学性能的影响

研究了经不同工艺深冷处理的Cr12钢的显微组织和力学性能。结果表明,深冷处理可以在一定程度上提高Cr12钢的硬度,明显提高其耐磨性,其中深冷处理6h后钢的磨损失重下降了45％。但淬火后进行深冷处理,再于180℃回火8h的Cr12钢的冲击韧度未能得到明显改善。     

固溶处理对T-250马氏体时效钢的组织及力学性能的影响

通过透射电镜(TEM)研究T-250马氏体时效钢组织变化,结合断口扫描电镜(SEM)观察,研究固溶温度和保温时间对T-250马氏体时效钢的组织及力学性能的影响。结果表明,T-250马氏体时效钢固溶态的硬度在280～292HB之间,几乎不受固溶温度和保温时间的影响;T-250马氏体时效钢中的马氏体形貌为板条状,且板条形貌不随固溶温度的升高和保温时间的延长而变化;固溶温度和保温时间对固溶态T-250马氏体时效钢的拉伸性能和冲击韧性的影响不大,固溶态T-250马氏体时效钢具有良好塑性和韧性。     

热处理对高强度捆带钢的组织和性能的影响

实验室研究了一种高强捆带钢的热处理工艺、组织和性能的关系.结果表明:含031%C-0.23%Si-1.43%Mn的冷轧板,经735～745℃的两相区迅速淬火+470℃中温同火后可达到1100 MPa以上的抗拉强度和10%以上的伸长率,用此工艺生产的捆带钢比传统的铅浴等温淬火工艺具有更高的强度.     

深冷处理对3Cr13组织和力学性能的影响

利用SLX-30程序控制深冷箱、金相显微镜、扫描电镜和洛氏硬度计,研究了刀剪材料3Cr13钢经普通热处理、深冷处理后的微观组织及力学性能变化。结果表明,与普通热处理相比.深冷处理后钢中析出的碳化物数量明显增加,分布更加均匀弥散;深冷处理后洛氏硬度值较普通热处理增加了5.3 HRC,冲击韧度增加了0.8 J。     

不同热处理温度对30MnSi钢组织及性能的影响

研究了淬火温度、回火温度、回火冷却介质对抗震30MnSi钢力学性能和微观组织的影响。结果表明,当淬火温度为910℃、回火温度为480℃、淬火水温为30℃时,试验钢筋具有最好的力学性能。     

热处理工艺对Nb-Ti低合金钢力学性能及组织的影响

以Nb-Ti低合金钢为研究对象,实验分析了3种不同的热处理工艺对奥氏体晶粒形态演化,以及材料微观组织和力学性能的影响,并分析了其影响机理。为低碳低合金钢的成分及热处理工艺优化提供了参考。     

热处理工艺对H13钢组织和力学性能的影响

比较了H13钢盐浴分级淬火、盐浴分级淬火＋200℃×2h回火、真空高压气淬和真空高压气淬＋200℃×2h回火后的力学性能,试验表明,H13钢真空高压气淬后的力学性能更为优良。这主要是因为H13钢盐浴分级淬火后,存在拉应力,而真空高压气淬后存在压应力;同时还与真空淬火具有脱气作用,残留奥氏体较多等因素有关。研究结果还表明分级淬火后应快速冷却,减少贝氏体量,增加马氏体转变量,抵消部分热应力,有利于减小模具的畸变和提高韧性。     

退火工艺对高强IF钢组织与性能的影响

以用高强IF钢为研究对象,研究不同退火工艺对其组织与力学性能的影响。结果表明,随着退火温度的升高,IF钢的抗拉强度逐渐降低,断后伸长率和屈强比逐渐升高。随着退火时间的延长,IF钢的抗拉强度与屈服强度先增加后降低。     

热处理对挤压铸造n-SiC_p/AZ91D镁基复合材料组织和力学性能的影响

采用金相、X射线衍射、扫描电镜(SEM)、拉伸试验等方法分析和测试了挤压铸造纳米Si C颗粒增强AZ91D镁基复合材料在铸态(F)、固溶态(T4)和人工时效态(T6)下的组织和力学性能。结果表明,固溶处理可使n-Si Cp/AZ91D铸态组织中的β-Mg17Al12共晶相溶入到基体中,形成单一的过饱和α-Mg固溶体,合金抗拉强度和伸长率均有大幅提高,分别达到265 MPa和13.7%;经时效处理后,复合材料的抗拉强度和屈服强度进一步提高,分别为275,145 MPa;SEM结果显示,β-Mg17Al12相主要以连续析出/非连续析出方式分别在晶内及晶界上析出,特别是纳米Si C颗粒分布对二次析出相β-Mg17Al12的形貌、尺寸、分布有一定的影响,使二次析出相变得细小和弥散分布,从而充分发挥了二次析出相的沉淀强化作用;最后对n-Si Cp/AZ91D复合材料不同热处理条件下的断口形貌进行了SEM观察,并且对其断裂方式进行了分析和讨论。