Ti微合金化对高锰钢组织和性能的影响

研究了Ti微合金化对Mn18钢组织和力学性能的影响,并分析了Mn18钢锤头失效的原因。结果表明,Ti微合金化在Mn18钢中具有细化晶粒、提高冲击韧性、伸长率、强度和硬度等作用,在Mn18钢加入0.10%和0.30%的w[Ti]时,随着Ti含量增加,高锰钢的硬度增大、强度提高,冲击韧性和延伸性也均呈优化趋势,继续增加w[Ti]至0.51%时,除布氏硬度继续增大外,KU2数值及稳定性、强度稳定性、伸长率等指标均出现下降趋势,高锰钢属于高氮奥氏体钢,加入Ti后迅速析出大量TiN,作为异质核心,起到系列有益作用,加入量过大,则TiN类夹杂物的尺寸过大,且出现局部聚集,将对Mn18钢的性能稳定性造成不利影响,也易于导致Mn18锤头断裂失效。在Mn18钢中使用Ti微合金化,为保证其有益效果,其含量不应超过0.30%。

Influence of Ti(C,N)precipitates on austenite growth of micro-alloyed steel during continuous casting

Austenite grain size is an important influence factor for ductility of steel at high temperatures during continuous casting. Thermodynamic and kinetics calculations were performed to analyze the characteristics of Ti(C,N) precipitates formed during the continuous casting of micro-alloyed steel. Based on Andersen-Grong equation, a coupling model of second phase precipitation and austenite grain growth has been established, and the influence of second precipitates on austenite grain growth under different cooling rates is discussed. Calculations show that the final sizes of austenite grains are 2.155, 1.244, 0.965, 0.847 and 0.686 mm, respectively, under the cooling rate of 1, 3, 5, 7, and 10 ℃·s^(-1), when ignoring the pinning effect of precipitation on austenite growth. Whereas, if taking the pinning effect into consideration, the grain growth remains stable from 1,350 ℃, the calculated final sizes of austenite grains are 1.46, 1.02, 0.80, 0.67 and 0.57 mm, respectively. The sizes of final Ti(C,N) precipitates are 137, 79, 61, 51 and 43 nm, respectively, with the increase of cooling rate from 1 to 10 ℃·s^(-1). Model validation shows that the austenite size under different cooling rates coincided with the calculation results. Finally, the corresponding measures to strengthen cooling intensity at elevated temperature are proposed to improve the ductility and transverse crack of slab.

Ti-Mg脱氧钢复合夹杂物诱导针状铁素体原位观察

以Ti-Mg脱氧钢为研究对象,采用热模拟和高温激光共聚焦显微镜(CLSM)研究了不同冷速对组织相变的影响以及连续冷却条件下原位观察晶内夹杂物诱导针状铁素(AF)体形成过程。结果表明:随着冷速的增加,AF含量先增加后降低,冷速为5℃/s时,AF含量最多;高温原位观察发现,614℃时AF开始在夹杂物处形核,553℃时形核长大结束。电子探针面扫夹杂物内层以MgO-Al_(2)O_(3)为主体,外层覆盖TiOx-MnO。贫Mn区的形成是诱导含Ti-Mg复合夹杂物诱导生成AF的主要原因。

Ti对中碳高硅锰合金钢组织及耐磨性的影响

利用SEM、EDS、Q10M显微维氏硬度计、RtecMFT-5000多功能往复式摩擦试验机、白光干涉仪等设备研究了不同Ti含量的中碳高硅锰合金钢的微观组织、显微硬度、析出相成分和形貌等特征,并进行了耐磨性分析与磨损机制解析。结果表明:Ti的适量加入可以有效细化晶粒,但过量Ti(0.7wt.%)的加入会导致晶粒粗化,并且Ti加入量的不同会导致析出物种类、尺寸与形貌的变化;硬度与摩擦磨损试验对比发现,Ti的添加总体上降低了中碳高硅锰合金钢的硬度,其耐磨性能得以提升主要依赖于合金化后析出的微米级TiC、TiN颗粒硬质相,0.5wt.%的Ti添加量可有效降低中碳高硅锰合金钢的硬度,同时降低摩擦系数,提高耐磨性,这主要归因于晶粒细化强化与析出强化作用。

Static Recrystallization Behavior of Hot Deformed Austenite for Micro-Alloyed Steel

Static recrystallization behavior of austenite for micro-alloyed steel during hot rolling was studied and the influence (τ-ε diagram) of holding time and deformation at different deformations and isothermal temperatures on microstructuralstate of austenite were discussed. Corresponding to parameter Z in the dynamic recrystallization diagram, parameterY was then introduced to simplify static recrystallization diagrams.

Effect of Mo on the continuous cooling transformation behavior of Nb-Ti micro-alloyed low carbon steel

The effect of molybdenum on the continuous cooling transformation behavior of the micro-alloyed low carbon steel containing niobium and titanium was investigated by a Gleeble 3800 thermo-mechanical simulator. The phase transformation temperature of the steel at various cooling rates was detected. The microstmcture was observed by optical microscope （OM） and scanning electronic microscope （ SEM）, and its Vickers hardness was tested. Based on these, its dynamic continuous cooling transformation （CCT） diagrams were determined. The results show that the transformation temperature from deformed austenite to acicular ferrite （AF） is decreased when Mo is added, and the formation of pro- eutectoid ferrite （F） and pearlite （P） is either inhabited or postponed. Mo can also enlarge the range of the cooling rate in forming AF, and refine the microstructure effectively.

1RK91不锈钢电渣重熔过程中Ti含量控制研究

为了实现电渣重熔1RK91不锈钢过程中Ti含量的精准控制,以CaF_(2)-CaO-Al_(2)O_(3)三元渣系为基础,通过向渣中添加一定量的MgO、TiO_(2)、Al进行电渣重熔试验。结果表明:在三元基础渣系中添加5%(质量分数,下同)MgO和4%TiO_(2),电渣锭Ti损失量可降低12.9%以上;添加5%MgO和0.4%Al粉时,随着渣中TiO_(2)含量的增加,电渣重熔锭Ti烧损量减小,TiO_(2)添加量达到10%时,出现烧铝增钛现象。试验确定了电渣冶炼1RK91钢的渣系调控方案,在基础渣系中添加5%MgO、7%TiO_(2)和0.4%Al粉,Ti烧损量可控制在2.5%以内,实现了Ti元素的精准控制。

中碳CrMo钢中Ti、Nb液析形貌及生成机理分析

通过观察微合金Ti、Nb、V在42CrMo钢连铸坯中的液析形貌,以及液析经加热轧制后的变化,同时,采用热力学计算的方式推导液析生成机理。结果表明,在含w[Ti]0.012%、w[Nb]0.030%、w[V]0.030%、w[N]0.003 5%的42CrMo钢410 mm×530 mm连铸坯中,可观察到Ti、Nb以复合碳氮化物的形式析出,形成微米级液析,w[Ti]较高(70%~83%)的多呈多边形块状,w[Nb]较高(70%~85%)的多呈薄膜状或不规则块状,液析中基本不含V元素;Ti和Nb的碳氮化物液析可互溶并共同生长,Nb含量较高的液析以Ti含量较高的液析为核心长大为块状,部分液析以含硫夹杂物为核心形核并长大;连铸坯心部的碳氮化物液析较多,并且尺寸较大(最长达35μm),连铸坯表面的数量较少,尺寸较小(10μm以下);连铸坯经1 200℃加热并轧制后,液析可部分回溶,数量减少,尺寸减小,并且在轧制过程中破碎。

Ti微合金化400 MPa级光伏支架用钢的开发

详细介绍了山西建龙1500生产线试制400 MPa级光伏支架用热轧钢带的成分设计、工艺路线以及产品质量情况。生产实践表明,按照设计的成分和工艺生产的光伏支架用热轧带钢的组织为铁素体+少量珠光体,拉伸性能和冷弯性能优异,能够满足用户的使用要求。

Al/Ti/Steel覆板爆炸焊接界面的显微组织特征

利用电子显微技术研究了Al／Ti／Steel覆板爆炸焊接中两个异种焊接界面的显微组织变化特征透射电镜直接取样观察到在界面处有组织过渡区，并且过渡区之间及过渡区与母材之间存在明显的边界Al／Ti界面过渡区为Al＋Ti混合组织；Ti／Steel界面由FeTi金属间化合物区和非晶区组成过渡区的形态和宽度与焊接过程中的合金元素扩散及冷却速度有关。

Effect of Hot Processing Technology on Mechanical Properties and Structure of Interface of Ti/Steel Composite Sheet

研究了热加工工艺对钛-钢复合板界面力学性能和显微组织的影响。测试了在A，B，C，D4种温度下热轧复合板界面的力学性能，用金相显微镜及扫描电镜观察了界面显微组织并分析了界面的成分。结果表明，在A，B2种温度下轧制的钛-钢复合板界面机械性能良好，延伸率高，其剪切强度不但可保持坯料原有的水平，甚至还略有增加。在C，D2种温度下轧制的钛-钢复合板界面机械性能相对较低，延伸率较高，但剪切强度要比爆炸复合坯料低，尤其是D加热温度，轧制后界面剪切强度急剧下降。热轧的终轧温度也是影响钛-钢复合板界面结合性能的重要因素。在低于相转变温度的合适温区热轧，且终轧温度合适，获得的钛-钢复合板结合界面无爆炸波纹，没有污染，生产的脆性化合物极细小，组织类同于钛材完全退火的等轴组织。

21Cr超纯铁素体不锈钢TiN析出的热动力学研究

非金属夹杂的数量和尺寸控制对钢铁的加工性能与使役行为有着重要影响.基本凝固理论对21Cr超纯铁素体不锈钢中TiN的析出条件进行数值求解,从理论上研究了TiN的热力学、动力学形成条件与析出规律.结果表明:试验钢钢液中无TiN析出,凝固过程中固液界面前沿发生溶质偏析富集,促使TiN在固相率f_(s)为0.15时开始析出.析出的TiN尺寸受钢液中Ti、N元素初始含量与凝固冷却速率的影响,降低Ti、N初始含量,提升凝固冷却速率均可减小TiN半径,Ti,N元素含量对TiN尺寸影响更加敏感,可通过降低钢液中N元素初始含量延迟凝固过程中TiN夹杂物的析出.实际生产中可调控钢液中Ti的添加量,使得TiN的数量与尺寸分布更加合理.

Precipitation characteristic of high strength steels microalloyed with titanium produced by compact strip production

Transmission electron microscopy （TEM） and physics-chemical phase analysis were employed to investigate the precipitates in high strength steels microalloyed with Ti produced by compact strip production （CSP）. It was seen that precipitates in Ti microalloyed steels mainly included TiN, Ti4C2S2, and TiC. The size of TiN particles varied from 50 to 500 nm, and they could precipitate during or before soaking. The Ti4C2S2 with the size of 40-100 nm might precipitate before rolling, and the TiC particles with the size of 5-50 nm precipitated heterogeneously. High Ti content would lead to the presence of bigger TiC particles that precipitated in austenite, and by contrast, TiC particles that precipitated in ferrite and the transformation of austenite to ferrite was smaller. They were less than 30 nm and mainly responsible for precipitate strengthening. It should be noted that the TiC particles in higher Ti content were generally smaller than those in the steel with a lower Ti content.

Precipitation behavior of Ti in high strength steels

Precipitation behavior of Ti in high strength steels was investigated by means of the equilibrium solid solubility theory. The contributions of Ti content to yield strength were calculated. The calculated results were verified by the hot rolling experiment for C–Mn steel and C–Mn–Ti micro alloyed steel, respectively. The research results show that the precipitates are mainly Ti N at the higher temperature. With the decreasing temperature, the proportion of Ti C in precipitates increases gradually. When the temperature drops to 800 °C, Ti C will become predominant for the precipitation of Ti. When Ti content is less than 0.014%(mass fraction), Ti has little influence on the yield strength. When Ti content is in the range of 0.014%–0.03%(mass fraction), the yield strength of Ti micro alloyed steel is greatly increased, which leads to instability of the mechanical properties of the steel. Therefore, the design of Ti content in high strength steels should avoid this Ti content range. When Ti content is higher than 0.03%, the yield strength increases stably. In this experiment, when added Ti content was controlled in the range of 0.03%–0.05%, the contribution to the yield strength of Ti micro alloyed steel can reach about 92.44 MPa.

Effects of B and Ti on the Toughness of HSLA Steel Weld Metals

Effects of microalloying Ti and B on the microstructures and low temperature toughness of manual metal arc (MMA) deposits were investi- gated.Weld metals containing 200-300 ppm Ti and 29-60 ppm B deposited by manual coated elec- trodes provided an optimum low temperature toughness.The addition of B in weld metals low- ered the γ→α transformation temperature which promoted the acicular ferrite (AF) transformation. Solid solutioned B suppressed grain boundary ferrite as well as side plate ferrite formation and benefited the acicular ferrite formation.Titanium protected B from oxidizing as well as nitriding and formed Ti-Mn silicate inclusions.Ultra-high volt- age electron microscope analyses showed that TiO structure in the Ti-Mn silicate inclusions was the favorable nucleation site for acicular ferrite forma- tion.

INFLUENCE OF PHASE COMPOSITION ON PITTING CORROSION RESISTANCE OF SPUTTERED COATING OF 1Cr18Ni9Ti STAINLESS STEEL

A series of single bcc,bcc plus fcc duplex and single fcc microcrystalline coatings of 1Cr18Ni9Ti stainless steel were prepared by using sputtering technique.The resistance against pitting corrosion was studied by measurements of pitting corrosion potentials and electrochemical noise during initiation of corrosion pits.The results show that the sputtered coatings with single bcc phase or single fcc structure are more resistant to pitting corrosion than those with bcc plus fcc duplex phase structure.

Morphology and orientation relationship of VC precipitates in HSLA steel

The morphology and distribution of VC precipitates in HSLA steel as well as the orientation relationship between VC precipitate and α-Fe were studied by transmission electron microscopy （TEM）. The chemical composition of the VC precipitate was analyzed qualitatively by using analytical electron microscopy （AEM） equipped with an energy dispersive spectrum （EDS） system. The VC precipitate is needle-like in shape with a size of about 10 nm in length and is homogeneously dispersed in the α-Fe matrix. The smaller lattice misfit along the 〈100〉 lattice direction of α-Fe matrix leads to VC precipitate forming with its long axes nearly parallel to the 〈100〉 lattice direction of α-Fe matrix. It is confirmed that the orientation relationship between VC precipitate and α- Fe is the ＂N-W＂ orientation relation by selected area electron diffraction （SAED） patterns.

FEM simulation on residual stress distribution during diffusion bonding between Ti （ C, N） metallic ceramic/interlayer/40Cr steel

Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.

Effect of Coiling Temperature on Ti(C,N) Precipitation and Properties of Batch Annealed DC06EK Enamel Steel

The effects of hot-strip coiling temperature on Ti（C,N） precipitation, texture and hydrogen permeation behavior in DC06 EK enamel steel were investigated by TEM, EBSD test and electrochemical hydrogen permeation experiment. It was found that the Ti（C,N） particles in hot-strip coarsened with increasing coiling temperature, whereas after cold-rolling and annealing, the size difference of Ti（C,N） particles was lessened. The hot-strip coiling temperature has a significant impact on the recrystallized texture in the subsequent cold-rolled and annealed sheet. Hot-strip using high temperature（700 ℃） coiling leads to strong {111} recrystallized texture in annealed sheet, with peak intensity 9.2. On the contrary, in annealed sheets using hot-strip coiling at 650 ℃, their {111} recrystallized textures were weaker, which was also reflected in their rmvalues. Even though the hydrogen diffusion coefficient is slightly lower（7.76×10^（-5） mm^2/s） in annealed sheet using low temperature coiling（600 ℃）, appropriately higher coiling temperature is more suitable for DC06 EK enamel steel combining both good drawability and fish-scale resistance.

Metallurgical and Corrosion Properties of Explosively Welded Ti6A14V/Low Carbon Steel Clad

Titanium alloy （Ti6Al4V） and low carbon steel （LCS） were joined by explosive welding method using different ratios of explosive. Some metallurgical properties of joined samples were investigated. Joined samples were examined by means of optical microscope, scanning electron microscope （SEM） and tensile-shearing tests. Bending, tensile, hardness and corrosion behaviour of the samples were investigated. Separation was not occurred on the joining interface after tensile-shearing and bending tests. It is seen that hardness of both plates were increased with increasing explosive. It is found that increasing explosive ratio leads to an increase in corrosion. It is also found that corrosion rate was high at the beginning of the experiment but the rate of the corrosion decreased subsequently during the experiment.