Neutron Scattering Study on Precipitation and Recrystallization Behaviours in P‐Free and P‐Alloyed IF‐Steel Sheets

In order to investigate the effect of coiling temperature and alloying of phosphorus (P) on the formation of precipitates and recrystallization behaviour, initial samples of P‐free and P‐alloyed IF‐steels were prepared by coiling at 580 and 720°C. Variations of precipitates and textures after coiling, cold rolling and recrystallization annealing were studied by means of small angle neutron scattering (SANS), neutron texture measurements and TEM observations. Hardness measurements and microstructure observations disclose that both coiling temperature and alloying of P affect softening of cold rolled samples. Coiling at a lower temperature increases the number of fine precipitates smaller than 10 nm in the hot band. Upon recrystallization annealing, precipitates ranging in size from 10 to 50 nm increase at the expense of fine particles smaller than 10 nm. Recrystallization behaviours in cold rolled IF‐steel samples were discussed by tackling the distribution of precipitates and the amount of solute P atoms in solution.     

Recovery and ordering in cold-rolled boron-doped Ni76Al24

The annealing behavior of a highly ordered intermetallic compound, i.e., boron-doped Ni₇₆Al₂₄, was studied for three degrees of cold rolling. The prerecrystallization phenomenon was found to consist of two mechanisms: recovery and restoration of order. The order parameter restored with annealing varied with the degree of cold rolling. Recovery was detected by a decrease in hardness and strain (measured by a half-maxima width). Ordering took place continuously in the case of 25 pct rolled material; however, the 85 pct deformed material showed that ordering was restored in two stages; the first stage was faster than the second. The 45 pct one showed some unusual features in ordering behavior. The hardness and strain parameter measurements also confirmed the presence of various stages before the onset of recrystallization. Those were verified by transmission electron microscopy and quantified in terms of the degree of order, which, in turn, depended on the degree of rolling.     

Zr-Sn-Nb-Fe合金加工过程中再结晶退火处理研究

以Zr-1.0Sn-1.0Nb-Fe合金为研究对象,对其挤压管坯、一次冷轧管坯及二次冷轧管坯进行真空退火处理,并采用偏光显微镜对每道次退火后的金相组织进行观察分析,研究了不同挤压温度以及不同退火制度对Zr-Sn-Nb-Fe合金再结晶退火处理的影响。结果表明:同一加工态下,600℃的挤压管坯在640℃/2 h退火发生再结晶程度大于640℃的挤压管坯,再结晶温度随挤压温度的降低而降低;在600℃的退火温度下,延长保温时间对锆合金再结晶程度影响不大;对挤压管坯、一次冷轧管坯的最佳退火温度为600℃/2 h,二次冷轧管坯的最佳退火温度为580℃/2 h或590℃/2 h。     

00Cr12Ti铁素体不锈钢的再结晶退火与成形性研究

 研究了1.0 mm厚 00Cr12Ti冷轧板在再结晶退火工艺条件下力学性能的变化规律。研究结果表明,随着退火温度的升高,维氏硬度、屈服强度、抗拉强度和屈强比均呈快速下降趋势,在超过800 ℃之后变化不大。再结晶退火后,00Cr12Ti钢拥有较多的{111}取向的晶粒,塑性应变比值r0、r45、r90和r-在退火温度超过780 ℃以后都有较大升高,并且r90>r0>r45。在700～800 ℃之间,平面各向异性Δr值变化不大,随后Δr值随温度上升急剧升高,因而成形时易产生严重的制耳现象。通过杯突试验发现,杯突值IE与r-值的变化相一致,表明00Cr12Ti冷轧板在高温再结晶退火后,可获得良好的成形性能。     

含氮马氏体不锈钢420U6冷轧板再结晶退火的热模拟试验

采用Gleeble-3800热模拟试验机并结合硬度法与金相法分别测定了压下率66%含氮马氏体不锈钢420U6的1 mm冷轧板定时条件下的再结晶温度和恒温条件下的再结晶时间,通过Arrhenius公式计算了试验钢的再结晶激活能。试验结果表明,当保温时间为60 s时,试验钢的再结晶温度为664.2℃当退火温度为780℃时,再结晶时间为7.7 s;再结晶激活能Qr为145.3 kj/mol。     

CSP工艺冷轧薄板盐浴退火再结晶实验

 研究了以CSP工艺热轧板卷为原料的冷轧薄板在盐浴退火过程中的再结晶行为,通过显微组织、显微硬度及电子背散射衍射技术观察、分析揭示了再结晶的规律,结果表明,CSP工艺冷轧薄板经盐浴退火后的再结晶组织为等轴状晶粒;在相同温度下盐浴退火,冷轧压下率较大时,完成再结晶所需的保温时间较短,再结晶晶粒细小。     

冷轧中锰钢退火过程中硬度及组织的演化

 利用EBSD技术研究了冷轧中锰钢在退火过程中的组织演化规律,从而揭示了其硬度变化的原因。研究结果表明:冷轧中锰钢在650℃退火,获得了0.3~0.6μm等轴状奥氏体和铁素体的超细晶组织,且随着退火时间的延长组织结构没有发生明显粗化;在550~650℃退火,随着温度的升高,奥氏体含量不断增加;在700℃退火时,奥氏体稳定性降低,出炉空冷过程中发生了马氏体转变,硬度升高;逆转变奥氏体相的稳定性主要受其碳含量控制,碳含量越高越容易获得大量稳定的逆转变奥氏体。     

Effect of Nb on Microstructure Evolution in Cold Rolled Dual-Phase Steels:Interaction of Recovery,Recrystallization and Phase Transformations

The effects of Nb addition,individually and in combination with Ti,were evaluated over a range of coiling temperatures.Coiling temperature influences the ratio of soluble and precipitated Nb in the hot rolled steel containing 0.08 % C and 2.2 % Mn.Nb bearing precipitates can co-precipitate on TiN and impact the microstructure and mechanical properties of the steel after annealing treatment.Microstructure characterization revealed that recovery and recrystallization processes preceded austenite formation.The effects of Nb on austenite formation in cold rolled steels during heating and isothermal holding and on austenite decomposition during subsequent cooling were investigated using dilatometry.The addition of Nb retarded ferrite recrystallization starting temperature,but had no significant effect on the starting temperature of austenite formation during heating.The Nb addition also accelerated austenite formation once the transformation started,and was beneficial for the formation of a finer and homogeneous microstructure.     

Recrystallization of deep drawing columbium (Nb)-treated interstitial-free sheet steels

The softening response after isochronal annealing of cold-rolled, Cb-treated, vacuum decarburized-deoxidized, interstitial-free steels was investigated by hardness measurements, tension tests, and optical and transmission electron microscopy. Softening after annealing, following cold reduction, occurs by recovery-recrystallization and a reduction in precipitation hardening due to the coarsening of CbC precipitates. The recrystallization start temperature increases markedly with increasing amounts of Cb in solid solution in ferrite. Fine CbC precipitates retard recrystallization to a much lesser degree, and their effects can be eliminated by coarsening prior to cold reduction. Recrystallization initiates at free surfaces. Partially recrystallized structures consist of two layers of recrystallized matrix separated by an unrecrystallized zone. The recrystallized layers thicken with increasing temperature or time. This phenomenon is an inherent characteristic of these steels and not a result of external influences.     

Recrystallization of deep drawing columbium (Nb)-treated interstitial-free sheet steels

The softening response after isochronal annealing of cold-rolled, Cb-treated, vacuum decarburized-deoxidized, interstitial-free steels was investigated by hardness measurements, tension tests, and optical and transmission electron microscopy. Softening after annealing, following cold reduction, occurs by recovery-recrystallization and a reduction in precipitation hardening due to the coarsening of CbC precipitates. The recrystallization start temperature increases markedly with increasing amounts of Cb in solid solution in ferrite. Fine CbC precipitates retard recrystallization to a much lesser degree, and their effects can be eliminated by coarsening prior to cold reduction. Recrystallization initiates at free surfaces. Partially recrystallized structures consist of two layers of recrystallized matrix separated by an unrecrystallized zone. The recrystallized layers thicken with increasing temperature or time. This phenomenon is an inherent characteristic of these steels and not a result of external influences.     

薄带连铸取向Fe-6.5％Si钢形变热处理过程组织演化

设计并利用双辊薄带连铸工艺制备出取向Fe- 6. 5%Si钢铸带,研究了热处理工艺对铸态、形变和初次再结晶组织、织构及析出物的影响规律。结果表明,铸带退火可以促进铸态组织中的柱状晶长大,同时增加200nm以下MnS- AlN或MnS- NbN复合析出物的面密度。随着铸带退火温度升高,冷轧组织中变形带宽度以及带内剪切带长度增加,初次再结晶织构中{111}〈112〉组分增强,{110}〈001〉晶粒所占比例增大。铸带退火有助于改善冷轧板高温退火过程中的二次再结晶行为,提升产品磁性能。     

邯钢罩式退火生产Ti-IF钢工艺

讨论了一种罩退Ti-IF钢的生产工艺,检测了75%和80%压下率条件下的再结晶温度,得出了与压下率相关的Ti-IF钢再结晶经验公式;通过数值模拟计算了不同罩退工艺条件下钢卷的冷点情况,预测了740℃保温15h是最佳罩退工艺;通过XRD检测了钢卷在不同退火工艺条件下的织构组成情况,分析了退火工艺对冲压性的影响。通过透射电镜检测出成品卷的析出物组成为TiN、TiS和Ti_4C_2S_2,未检测出TiC和AlN粒子,说明成品中的碳、氮在热轧加热前已经被钛完全固定,其成分、工艺设计满足IF钢的设计要求。     

深冲搪瓷钢DC03EK析出物及其抗鳞爆性能分析

对DC03EK深冲用冷轧搪瓷钢铸坯、热轧基料进行析出物检测,对其冷轧成品卷进行析出物、抗鳞爆敏感性TH值、成形极限FLD测试。结果表明,DC03EK深冲用冷轧搪瓷钢材料中存在弥散分布的Ti(C,N)、TiN、TiC、TiS、Ti4C2S2和极少量的MnS等析出物,铸坯中析出物颗粒较大,经热轧轧制较大颗粒析出物变小,经冷轧轧制及罩式退火后,析出物变得细小并弥散分布,使得DC03EK具有高的抗鳞爆敏感性TH值,同时又具有良好的成形性。     

退火工艺对铁素体不锈钢SUS410L热轧钢板组织和性能的影响

研究了不同退火温度和保温时间对SUS410L热轧态钢板再结晶行为和力学性能的影响。试验结果表明,当保温温度为700℃时,保温480 min后SUS410L热轧钢板仍未完成再结晶。当保温温度为750℃和800℃时分别于120 min和30 min基本完成再结晶,晶粒在之后的保温时间里逐步长大。为避免退火过程中出现马氏体而降低材料的延伸率,退火温度≤800℃。材料的力学性能与热处理后的再结晶程度密切相关。当保温温度为750℃且保温时间为480 min时可获得最佳的综合机械性能:延伸率38%,HRB硬度值67,屈服强度236 MPa,抗拉强度441 MPa。     

Effect of copper precipitation on the development of recrystallization textures through continuous annealing of low-carbon sheet steel

The development of {111} recrystallization textures in 0.5 pct and 1 pct Cu-containing steels through a simulated continuous annealing cycle has been investigated. A low-carbon content of 0.05 pct compared with extra low-carbon content of 0.005 pct accelerated the precipitation of ε-Cu by preaging prior to cold rolling, and a nickel content up to 0.95 pct gave the adverse effect. Pole intensity ratio, I₂₂₂/I₂₀₀, of the cold rolled and continuous-annealed sheet depended more strongly upon the distribution density of ε-Cu particles than upon the amount of carbon in solid solution. The optimum dispersion of e-Cu precipitates for producing a strong {111} texture was about 300 particles per μm³ in distribution density, and 20 to 30 nm in particle size. Also, it was suggested that through continuous annealing by utilizing the effect of prior precipitates such as ε-Cu, a high strength, dual-phase steel with a highr-value could be produced. Formerly Graduate Student, Kyushu University     

不同退火工艺下TWIP钢微观组织及力学性能演变

摘要：以在650℃温轧的Fe-24Mn-2Al-1Si-0.05C TWIP钢为研究对象,通过金相显微镜(OM)、扫描电镜（SEM）、透射电镜（TEM）、室温拉伸等实验手段,研究温轧TWIP钢在回复退火、部分再结晶退火、高温短时退火以及高温退火等不同退火工艺下其微观组织及力学性能的演变。结果表明,随着退火工艺的改变,实验钢的微观组织由回复退火时包含高密度位错、形变孪晶等的变形晶粒逐渐向高温退火时的无畸变再结晶晶粒转变;而部分再结晶退火时,实验钢的微观组织由未再结晶区的变形晶粒和细小的再结晶晶粒混合组成。随退火工艺的改变,实验钢拉伸前、后的硬度变化趋势为先下降然后基本不变最后上升;实验钢的变形机制逐渐由位错滑移为主向孪生滑移为主转变。     

Coercive force and microstructure in a Zr-permalloy

An alloy containing 80.0 pct Ni, 12.65 pct Fe, 6.74 pct Mo, 0.36 pct Zr, and 0.25 pct Mn by weight was cast, homogenized, and successively cold rolled into thin strips with area reductions of 0, 50, 75, and 90 pct. Annealed samples were studied by optical and electron microscopy, electron diffraction, and magnetic testing to determine the effects of cold work and annealing upon the microstructure and magnetic properties of the alloy. Cold work produced a high initial hardness together with high coercive force. Recrystallization of the cold worked structures occurred upon annealing at 600°C (873 K) and above and caused significant and parallel decreases in hardness and coercive force. The activation energy for recrystallization was found to be 80.5 kcal/g mole (337.0 kJ/g mole) for the 50, 75, and 90 pct cold worked specimens. After annealing at 600°C (873 K), a small number of spherical Ni₄Mo particles were observed, but the particles produced little change in magnetic properties apparently because of their relatively coarse size and large spacing. Beginning at 700°C (973 K) ribbon-shaped particles of a Ni₅Zr intermetallic compound also precipitated out of solid solution. Both the Ni₄Mo and Ni₅Zr precipitates were the result of a homogeneous continuous precipitation reaction within the grains. A peak in coercive force at 800°C (1073 K) is attributed to domain wall pinning associated with the fine distribution of rodlike Ni₅Zr particles. Cold working 90 pct and aging at 800°C (1073 K) was found to increase coercive force by almost 60 pct from the minimum produced by complete recrystallization. Annealing, however, decreased hysteresis and improved squareness.     

双相区热处理对430铁素体不锈钢热轧板组织和性能的影响

研究了α+γ双相区热处理对430铁素体不锈钢热轧板显微组织和力学性能的影响,并与工业罩式炉退火后的热轧板显微组织和力学性能进行了对比分析。结果表明:在双相温度区间对430不锈钢热轧板进行热处理,分割了热轧板轧向的条带状组织,抑制了聚集组织的形成。与常规罩式炉退火工艺相比,双相区热处理显著提高了430不锈钢热轧板的伸长率,降低了屈服强度和硬度,有利于改善最终冷轧产品的冲压性能和抗起皱性。     

耐大气腐蚀冷轧钢带Q310NQL2罩式炉退火工艺分析

实验室模拟罩式炉工艺对Q310NQL2耐大气腐蚀冷轧钢带进行8个不同温度的退火,分析了退火钢带力学性能、硬度及显微组织随温度的变化。结果表明,强度随着温度升高呈现出两个“平台区”和一个“骤变区”,最终确定了耐大气腐蚀冷轧钢带Q310NQL2的再结晶温度为650 ℃。采用罩式炉工业化生产耐大气腐蚀冷轧钢带Q310NQL2,退火温度冷热点设定为660/680 ℃,保温时间设定为12 h,钢带完成了再结晶过程的同时,力学性能、晶粒度等级均满足标准要求。