430不锈钢冷轧板再结晶组织演变以及动力学模型

以现场高温连续退火工艺为基础,利用热模拟机研究了冷轧430薄板在650℃到875℃范围内等温退火过程,对不同退火温度下组织随保温时间的演变规律进行了详细的分析,并建立了该材料的再结晶动力学方程。结果表明:退火温度对材料再结晶的孕育期和完全再结晶所需时间有很大的影响,材料分别在850℃、825℃温度下保温34 s、5 min即可完全再结晶;当温度低于800℃时,材料在实验时间范围内均无法完全再结晶。通过硬度法确定了不同退火温度下材料的再结晶率随保温时间的变化关系,并建立了JMAK型再结晶动力学方程,Avrami指数n的值在0.5~1.0之间,再结晶激活能Q activ为309.12 kJ/mol。     

铈对低铬铁素体不锈钢静态再结晶行为的影响

为研究铈对低铬铁素体不锈钢的静态再结晶行为的影响,冶炼含铈和不含铈的00Cr12不锈钢,在Gleeble-3800型热模拟试验机上采用双道次压缩法,测量不同温度下、不同道次间隔时间试验钢的应力应变曲线,计算再结晶体积分数,评价材料静态再结晶行为;对试验钢在不同温度下退火,侵蚀后进行组织观察。结果表明:铈的添加可抑制试验钢静态再结晶的进行,提高试验钢的再结晶温度,细化晶粒,铈含量0.028wt%时可将00Cr12不锈钢的静态再结晶激活能由103kJ/mol提高到114kJ/mol。铈在晶界的偏聚,对晶界起到拖拽作用,降低了晶界迁移速度,从而抑制了静态再结晶行为。     

Nb、Ti对铁素体不锈钢铸态及热轧态组织、织构的影响

研究了不同Nb、Ti添加情况下铁素体不锈钢的铸坯组织特征以及热轧后板材的组织和织构.研究结果表明:Nb的添加可以明显细化铸坯组织,而Nb、Ti双稳定元素的添加强烈地促进了铸坯组织晶粒的等轴化和晶粒细化.Nb、Ti元素的加入不仅可以细化铸坯组织,同时也可以细化热轧后的板材组织,单独添加的Nb、Ti元素均可以推迟板材的再结晶过程,Ti的作用更为明显,而Nb、Ti的同时加入可明显推迟板材的再结晶过程.     

Nb-Ti-Al高温合金的再结晶动力学和晶粒长大行为

研究了Nb-Ti-Al高温合金的静态再结晶行为及晶粒长大行为,并通过实验得出了再结晶动力学和晶粒长大方程.结果表明:冷轧变形后,合金在880～1000℃进行退火处理,可获得均匀、细小的晶粒,再结晶晶粒体积分数与退火时间的关系可用Avrami方程进行描述.随着冷轧变形量的增加,再结晶激活能逐渐减小,其范围为274.05 ～ 198.45 kJ/mol.在850 ～1000℃的温度范围内,研究了加热温度和时间对合金晶粒尺寸变化的影响.     

TB8钛合金板材再结晶动力学

对TB8合金冷轧板材在770~820℃温度范围内的再结晶动力学研究表明:试验用TB8钛合金冷轧板材的再结晶最佳退火温度为790~810℃。采用Avrami方程可以较好的描述冷轧TB8合金板材退火过程的再结晶情况。800℃退火处理动力学拟合方程为:lnln[1/(1?x?t?)]??2.38?0.86lnt。由实验数据计算得到合金再结晶激活能为102.87 k J/mol。     

17%Cr铁素体不锈钢的再结晶组织与织构特征

利用电子背散射衍射(EBSD)技术研究了17%Cr铁素体不锈钢退火时间对组织、织构的影响。研究了再结晶晶粒的显微组织、微观织构和晶粒间取向分布与成形性的关系。结果表明,随着退火时间的延长,再结晶晶粒长大,γ取向线上{111}110,{111}112的先增强后减弱,α取向线上的{112}110,{111}110先减弱后增强。当在1040℃退火时间为3 min时,γ织构密度最高,r值最大,△r的绝对值最小,此时获得了此钢种最好的成形性能。     

热处理过程中430不锈钢的再结晶行为及其数学模型研究

研究热处理过程中430不锈钢的再结晶行为,对其微观组织和硬度演变过程进行分析,同时建立了描述再结晶过程的JMAK模型。结果表明,完全再结晶所需的时间会随着热处理温度的升高而明显缩短。温度为800~875℃时,430不锈钢的软化作用明显,硬度明显下降。     

形变Cu-4Al合金再结晶动力学

测试了Cu-4Al合金经50％变形后在不同温度下再结晶动力学曲线，并根据公式G＝G0exp(-Q/RT)计算出再结晶激活能。     

热轧退火态430不锈钢的高温抗氧化性能

研究了热轧退火态的430铁素体不锈钢在700~900℃的高温氧化行为,测量了其恒温氧化增重曲线,利用扫描电镜(SEM)和能谱仪(EDS)观察分析了氧化表面形貌和组成,使用X射线衍射仪(XRD)鉴定了氧化物的种类。结果表明:在700℃生成的Cr2O3氧化膜不足以覆盖基体,材料氧化缓慢;800℃时氧化速率相对较大,生成的氧化物主要为Cr Mn1.5O4和Fe2O3;900℃时氧化十分迅速,材料表面有大量Fe2O3突起;退火温度对材料高温氧化性能影响不大。     

热轧退火态430不锈钢的高温氧化行为

研究了热轧退火态的430铁素体不锈钢在700~900 ℃的高温氧化行为,测量了其恒温氧化增重曲线,利用扫描电镜（SEM）和能谱仪（EDS）观察分析了氧化表面形貌和组成,使用X射线衍射仪（XRD）鉴定了氧化物的种类。结果表明：在700 ℃生成的Cr2O3氧化膜不足以覆盖基体,材料氧化缓慢;800 ℃时氧化速率相对较大,生成的氧化物主要为CrMn1.5O4和Fe2O3;900 ℃时氧化十分迅速,材料表面有大量Fe2O3突起;退火温度对材料高温氧化性能影响不大。     

Recrystallization of cold-drawn stainless steel

Summary Lengthening the holding time during the heating of cold-drawn 1Kh18N9T steel tubes reduces the initial and final recrystallization temperatures.An intensive lowering of the recrystallization temperature range occurs within the initial 10 min.The recrystallization process develops during the treatment of cold-drawn tubes at 975 to 1050°C as a result of heating without holding, and at 750 to 850°C by heating and a 3 hr holding period.     

热轧复合不锈钢-碳钢复合板界面特征

研究了热轧不锈钢-碳钢复合界面的组织形貌、成分、硬度变化及结构特征。结果表明热轧复合碳钢—不锈钢复合板的复合界面两侧存在一定厚度的扩散层。由于元素扩散及碳化物的生成,复合界面附近硬度升高。对于基层碳钢,靠近界面处显微硬度值最高,而对于复层不锈钢,在距界面处一定距离,显微硬度达到最高值。复合界面剥离后呈现等轴韧窝形貌,表明通过热轧复合的方法,不锈钢和碳钢之间能够实现良好的复合。     

Antibacterial mechanism of Cu-bearing 430 ferritic stainless steel

Copper(Cu)-bearing stainless steel has testified its effectiveness to reduce the risk of bacterial infections.However,its antibacterial mechanism is still controversial.Therefore,three 430 ferritic stainless steels with different Cu contents are selected to conduct deeper research by the way of bacterial inactivation from two aspects of material and biology.Hereinto,electrochemical and antibacterial results show that the increase in Cu content simultaneously improves the corrosion resistance and antibacterial property of 430 stainless steel.In addition,it is found that Escherichia coli(E.coli)on the surface 430 Cu-bearing stainless steel by the dry method of inoculation possesses a rapid inactivation ability.X-ray photoelectron spectroscopy(XPS)aids with ion chelation experiments prove that Cu(Ⅰ)plays a more crucial role in the contact-killing efficiency than Cu(Ⅱ),resulting from more production of reactive oxygen species(ROS).     

410不锈钢锻后退火工艺

现有文献资料上对410不锈钢锻后退火的工艺提法不同,为了确定适合的退火工艺,根据现有文献资料,选取不同参数进行试验,通过对硬度和金相组织的对比,确定了780℃退火、保温2.0~3.0 h、出炉后自然空冷的不完全退火工艺,并严格执行410不锈钢锻造工艺,控制终锻温度在900℃以上。该工艺在生产中进行了实践,结果证明,退火工艺达到了保证180~220 HBW的硬度范围、提高切削性能的预期。此不完全退火工艺与完全退火工艺相比,锻件的硬度合格率、机械加工性能和生产效率都得以提高,产品最终力学性能也得到了相应的提高,从而说明了该退火工艺具有较强的实用性和良好的经济效益。     

Corrosion of hot-rolled 430 stainless steel in HCl-based solution

The mixtures of hydrochloric acid and hydrogen peroxide were employed as the environmental friendly pickling solution for 430 hot-rolled stainless steel in this study. Increase of HCl concentration accelerates the corrosion rate of base metal, however aggravates the intergranular attack in sole hydrochloric acid solution. Addition of oxidant (H₂O₂) boosts the corrosion potential of stainless steel significantly resulting in the change of electrode action. At high oxidant content (0.6?mol?l^?1 H₂O₂), a corrosion product film accumulates onto the surface and the corrosion is then governed by the mass-transport at the film/stainless steel interface. The random dissolving of metal ions because of the film leads to brightening of stainless steel surface and the local corrosion is suppressed.     

铁素体不锈钢板坯连铸机技术要点

结合铁素体不锈钢连铸过程高温凝固特性,拟新建的双流铁素体不锈钢板坯连铸机采用直弧型连续弯曲连续矫直的特殊技术,选用全程无氧化浇铸、大容量中间包、结晶器自动液面控制减少钢水中夹杂物;采用摩擦力监测、结晶器漏钢预报保证浇铸的连续性;合理设计动态一冷和二冷配水等提高铸坯表面质量,并设计采用电磁制动、低过热度浇铸、二冷电磁搅拌、二冷动态轻压下技术提高铸坯内部质量。     

铁素体不锈钢表面皱折及其评价方法

皱折缺陷是中铬铁素体不锈钢发生较大塑性变形后容易出现的表面缺陷。这种缺陷往往破坏了不锈钢制品的外观,因此需要对制品进行研磨和抛光以消除皱折的影响。然而,额外的加工工序大幅增加了企业的生产成本,同时不可避免地造成了环境污染。那么,正确认识和评价铁素体不锈钢的表面皱折缺陷就显得非常重要。本文主要讨论界定铁素体不锈钢表面皱折缺陷,并简要介绍表面皱折缺陷的形成原因,进而厘清表面皱折缺陷的评价参数,最后针对已有测试方法存在的问题提出可供参考的解决办法。     

Characterisation of ferritic stainless steel by Barkhausen techniques

Magneto-acoustic emission (MAE) and magnetic Barkhausen noise (MBN) sensing techniques were developed and employed to characterise plastically deformed and heat-treated AISI 430 ferritic stainless steel samples. These results have been compared to the mechanical hardness, coercivity and residual stress of the samples. MAE and MBN were shown to decrease with increasing permanent material deformation. It was found that the inverse of MAE (absolute energy) and MBN (RMS) are linearly proportional to hardness. With increased deformation, the resultant change in dislocation density was found to effect material coercivity. It has been shown that the inverse of MAE absolute energy and MBN have an exponential relationship to the change in material coercivity. The results are explained in terms of the different mechanisms that effect dislocation-domain wall interactions. A new measurement parameter has been developed for microstructural characterisation called MAE absolute energy and has proved to be a useful quantitative method in MAE waveform measurement.     

Continuous dynamic recrystallization of AISI 430 ferritic stainless steel

The high-temperature deformation behavior of AISI 430 ferritic stainless steel was studied by torsion tests. The deformation tests were performed in the temperature range of 900–1100°C and strain rate range of 5.0×10⁻² −5.0/sec. The evolutions of flow stress and microstructure show the characteristics of continuous dynamic recrystallization (CDRX). The flow stress gradually decreased with strain over the peak stress without steady state. Below the 100% effective strain, grains appeared in small angle grain boundaries with a misorientation of 3–9°. In addition, when heavy deformation (>300%) was applied, higher misorientation (∼15°) was achieved. The tendency of CDRX increased with increasing strain rate and decreasing temperature. The dependence of CDRX grain size on the strain rate and temperature was discussed.