Deformation prediction of porcelain-enameled steels with strain history by press forming and high-temperature behavior of coating layer

Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of cleaning.The typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the substrate.This firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel substrate.The aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including firing.The FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating layer.The validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the substrate.The results reveal that the FE analysis results agree well with the experimental results with 8% error.

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.

Microstructure and properties of Ti-bearing hot-rolled high-strength steel plates for two-sided enameling

The composition and production technology of the type of hot-rolled steel plate used in two-sided enameling were briefly described. The microstructure and mechanical properties before and after enameling were contrastively investigated,and the precipitates in the samples were analyzed using transmission electron microscope and energy dispersive spectrometer. The results show the ferrite grain size of the steel plate after high-temperature enamel firing to be fine,with a large number of TiC and Ti;C;S;precipitates dispersed throughout the ferrite matrix. After two rounds of enamel firing at a temperature range of 800-890 ℃,its yield strength can still reach342 MPa. The results of a hydrogen permeation test show that the hydrogen storage properties of the steel plate are much better than those of ordinary structural carbon steel. A better bubble structure in the enamel layer can be obtained by this steel plate,with no fish-scale defects on the enameled steel-plate surface.

Study on microstructure and properties of cold-rolled high strength steel for enameling

With its superior comprehensive properties, cold-rolled enameling steel is widely applied in many fields. However, its low yield stress greatly limits its application. This study aims to improve the yield stress of cold-rolled enameling steel under the premise of meeting formability and enameling properties by strengthening the ferrite matrix via solid strengthening of Mn. The grain size of ferrite before and after enameling,mechanical properties of annealed steel, and precipitation behavior of second-phase precipitates are obtained through studying the microstructure and properties of enameling steel at different stages. The microstructure of the steel investigated at room temperature is found to contain equiaxial ferrite and bunchy cementite particles;the ferrite grains have grown to some extent after enameling. The fine dispersed TiC particles and cementite particles contained in the annealed steel are the main factors improving the hydrogen storage capability. Finally, the result of a falling-ball impact test shows that the steel has achieved excellent adherence.

Prevention of burn-on defect on surface of hydroturbine blade casting of ultra-low-carbon refining stainless steel

The burn-on sand is common surface defect encountered in CO2 -cured silicate-bonded sand casting of hydroturbine blade of ultra-low-carbon martensitic stainless steel,its feature,causes and prevention measures are presented in this paper.Experiments showed that the burn-on defect is caused by oxidization of chromium in the molten steel at high temperature and can be effectively eliminated by using chromium-corundum coating.

Causes of the formation of pit defects on the surface of the enamel layer

During the production of the inner walls of ovens,pit defects were formed on the surface of the enamel layer that was enameled on the cold-rolled steel via electrostatic powder spraying and sintering.The paper elaborates on the microstructure and element distribution of the enamel-steel interface and the enamel layer.Optical microscopy,scanning electron microscopy,and energy-dispersive spectroscopy were adopted to investigate the microstructure of a longitudinal section of the defect,and the pit-forming causes were analyzed.The results show that rusty spots lead to pit defects.During high-temperature firing,there is an inadequate fusion and reaction between iron oxides of the rusty spots and the enamel glaze.The rusty spots are closely related to pretreatment process;thus,to avoid their occurrence,electrostatic powder spraying and sintering should be performed timely after forming,degreasing,and thorough drying of the metal sheets.

酸洗搪瓷钢密着性能影响关键因素研究

为提高酸洗搪瓷钢的密着性能,研究了酸洗搪瓷钢密着性能的影响因素,包括烧搪时间、脱脂效能、表面色差和表面粗糙度,对不同脱脂程度、表面状态及粗糙度的试样进行涂搪和烧搪,并采用落球冲击法对密着性能评级。结果表明:在850℃进行烧搪时,烧搪时间从5 min延长至10 min,密着等级从2.0级提高至1.0级。同时,烧搪5 min时,脱脂不充分、保护渣增碳所致色差和降低粗糙度都会降低钢板和瓷釉之间的密着性能,其中脱脂不充分和色差的影响可通过延长烧搪时间至10 min进行改善,但延长烧搪时间后,粗糙度对密着性能仍存在显著影响。

等离子喷涂硅酸盐搪瓷涂层及其热循环行为研究

[目的]硅酸盐搪瓷涂层在冷热循环过程中的失效行为很少受到关注。[方法]采用喷雾造粒与烧结相结合的方式制备了多组分硅酸盐团聚烧结喷涂粉末材料,随后采用大气等离子喷涂技术在12CrMoV合金钢表面制备了SiO_(2)-Al_(2)O_(3)-Na_(2)CO_(3)-CaO基硅酸盐搪瓷涂层,研究了该涂层的微观组织和在700℃下的水淬热震循环行为。[结果]硅酸盐团聚烧结喷涂粉末材料呈球形,粒径分布在20~60μm之间。等离子喷涂硅酸盐涂层呈明显的堆叠层状铺展沉积,表面较为粗糙,其内部虽然存在一定数量的闭孔,但整体较为致密,除了含有一定数量的非晶相,还有SiO_(2)、Al_(2)SiO_(5)和Ca_(2)MgSi_(2)O_(7)晶相。该涂层在700℃水淬热震循环145次后发生部分脆性剥落。[结论]热震循环过程中发生的金属基体氧化、晶相分解,以及冷热交变循环等因素产生的热应力可能是导致涂层失效的原因。

铸坯火焰清理深度对超低碳冷轧搪瓷钢搪瓷性能的影响

通过研究调整铸坯火焰清理深度,验证超低碳冷轧搪瓷钢的抗鳞爆性、密着性以及氢渗透性的变化情况。研究结果表明,铸坯火焰清理深度从4mm降低至2mm,超低碳冷轧搪瓷钢没有出现鳞爆现象,密着等级无变化。氢渗透试验结果显示,降低铸坯火焰清理深度至2mm后,氢渗透时间和抗鳞爆敏感性TH值无明显变化,且TH值均>10min/mm^(2),抗鳞爆性能优良。

提高高钛超低碳搪瓷钢可浇性生产实践

针对高钛超低碳搪瓷钢可浇性差、水口易结瘤情况,对水口结瘤物和结瘤原因进行了机理分析。后续通过强化钢包顶渣改质,降低了顶渣氧化性。全工序低氧位控制,减少氧化铝夹杂物的产生。合理地控制RH循环时间和精炼后钢水镇静时间,严格执行保护浇注和控制大包下渣等措施,钢水可浇性大幅提高,实现搪瓷钢连浇炉数由原来3炉提高至6炉。

冷轧搪瓷钢切边质量控制与改善

基于冷轧连退线圆盘的剪切边原理,对影响冷轧搪瓷钢边部质量的原因进行了研究。结合现场工况,对原料宽度和缺陷进行检测,改进了刀片质量,同时对圆盘剪切边工艺参数、刀片倾斜角及去毛刺辊等进行了调整。通过一系列措施的制定,保证了搪瓷钢边部质量合格,毛刺控制在厚度的1%~3%以内,切边质量不合格率控制在0.8%以内,提高了产品一次命中率和产品形象。

冷轧超低碳搪瓷钢板的开发

简要介绍了冷轧超低碳搪瓷钢板的成分特点及工艺要求 ,分析了钢板的组织结构及析出相 ,研究了冷变形对氢在钢板中扩散系数和穿透时间的影响。实际批量生产结果表明 ,以超低碳为基础、添加适量的合金元素 ,采用合适的工艺制度生产的冷轧钢板既具有优良的成形性能 ,又具有优良的抗鳞爆性能。

退火温度对DC05EK搪瓷用钢贮氢性能的影响

研究rDC05EK冷轧搪瓷用钢板贮氢能力随退火温度的变化规律，分析了析出物对氢渗透时间的影响．结果表明：随着退火温度的升高，小尺寸析出物数量减少，降低了实验钢的贮氢能力，氢渗透时间缩短．退火温度在730～850℃之间，随着退火温度的提升，1mm厚实验钢板的氢渗透时间从16．5min下降到11．9min；退火温度升高至870℃，由于细小弥散析出物的反向溶解，导致氢渗透时间急剧缩短为3．6min，贮氰能力不足；DC05EK冷轧搪瓷用钢合适的连续退火温度范围是730—850℃．

Ti对DC01EK冷轧搪瓷用钢组织性能的影响

针对部分普通钢涂搪后由于H原子扩散导致鳞爆现象,在DC01EK钢中添加Ti元素,研究了Ti对钢板退火过程的再结晶行为及其贮氢性能的影响。结果表明,Ti的添加可形成大量粗大、弥散的第二相粒子Ti4C2S2,阻碍了再结晶过程,改变了钢板的再结晶温度范围,形成了大量的贮氢陷阱,有效提高了钢板的贮氢性能。

IF钢搪瓷板析出相的研究

20 0 1年武钢开始生产冷轧 IF钢搪瓷板 ,为了解 IF钢搪瓷板成分设计的合理性和优化生产工艺 ,在透射电镜上观察了钢中析出相的形态 ,用能谱仪分析了析出相的成分 ,并对析出相的平衡进行了计算。研究结果表明 :IF钢搪瓷板中的析出相主要为 Ti S、Ti4C2 S2 、Ti N以及细小的 Fe Ti P相 ;钢的碳含量增加和低的热轧加热温度有助于 Ti4C2 S2 相的析出 ;钢中富余的固溶 Ti将在退火温度下形成 Fe Ti P相 ;粗大的 Ti S、Ti4C2 S2析出相 ,既使钢板具有良好的涂搪性能 ,又对钢的深冲性能无有害影响 ,因此 。

稀土、钛和铌对冷轧超低碳搪瓷钢板成形性能的影响

在实验室加工了具有不同稀土、钛和铌含量的冷轧搪瓷钢板,测定了钢板的再结晶温度和模拟退火后钢板的成形性能,并观察了其金相组织,分析了钢中的第二相粒子。结果表明,在单加稀土、复合添加稀土+钛或稀土+钛+铌的3种钢中,单加稀土的钢再结晶温度最低,而含稀土+钛+铌的钢再结晶温度最高;经高温退火后,含稀土+钛+铌钢的伸长率和r值在3者中最高,达到了超深冲(即EDDQ)级别。

热轧高强双面搪瓷钢板组织与性能研究

介绍了鞍山钢铁股份有限公司热轧高强双面搪瓷钢板的生产工艺、组织和性能,并分析了实现良好的双面搪瓷性能和高屈服强度的机理,该钢板完全满足用P04型致密瓷釉双面搪瓷的可搪性要求,且钢板搪后屈服强度达到280MPa以上。

冷轧超低碳钢的析出相和氢穿透时间研究

介绍了加钛、稀土等超低碳钢的化学成分和合金特点,分析了钢中析出相的类型、尺寸和数量,测定了氢在钢中的穿透时间和扩散系数,研究了析出相对氢在钢中穿透时间的影响。结果表明,添加足量钛或复合添加稀土、钛和铌的超低碳钢既具有超深冲性能,又具有足够长的氢穿透时间,从而实现了成形性能和抗鳞爆性能的良好匹配。

退火方式对低碳冷轧搪瓷用钢组织性能的影响

研究了罩式退火及连续退火工艺对低碳冷轧搪瓷用钢组织性能的影响规律。结果表明,实验钢中的贮氢陷阱以MnS和Fe3C为主,且罩式退火及连续退火工艺均能使实验钢的成形性能及抗鳞爆性能满足要求。连续退火的退火温度较高,再结晶织构发展充分,得到更优的力学性能及成形性能;罩式退火保温时间长,更有利于析出物的析出,从而增加第二相粒子作为贮氢陷阱得到更优的抗鳞爆性能,对比得出了最优工艺流程,为实验钢的工业化生产提供了理论依据。

退火方式对含硼冷轧深冲搪瓷钢组织性能的影响

在实验室条件下研究了罩式退火和快速连续退火两种方式对含硼搪瓷钢微观组织、力学性能和抗鳞爆性能的影响.结果表明:适当增加Mn,S的质量分数和添加微量B,实验钢不同方式退火板的性能均较好;连续退火板强度稍高于罩式退火板,伸长率A_(50)和rm值明显高于罩式退火板,综合力学性能较好;连续退火板的氢扩散速率明显小于罩式退火板,主要得益于采用快速连续退火得到的实验钢中铁素体晶粒内存在大量弥散分布的渗碳体颗粒作为有效氢陷阱;采用快速连续退火可以实现含硼搪瓷钢良好的力学性能和抗鳞爆性能的匹配.