RH真空精炼脱碳模型参数辨识及应用

阐述了RH真空处理脱碳原理和真空脱碳算法,分析了表观脱碳速率的影响因素,针对影响因素具有多样性、复杂性和不确定性的特点,结合实际生产和经验数据,采用RBF神经元网络建立表观脱碳速率模型,在实际生产中通过该模型提高了真空处理脱碳模型预测精度.     

50Mn2V钢板脱碳层超标分析及工艺优化

简要介绍了钢板脱碳机理以及影响脱碳的因素(加热温度、加热时间、加热炉内气氛).分析实际生产中造成50Mn2V钢板脱碳的原因,提出了通过改变加热时空燃比、加热炉内压力,对加热工艺进行优化,合理安排生产组织,使50Mn2V钢板脱碳层超标问题得到解决.     

固态炼钢新工艺研究的提出与进展

固态炼钢是由铸铁薄板通过气-固反应形式脱碳生产薄钢板带的一种新工艺。近年来,气-固反应脱碳研究主要集中于电工钢的脱碳,本文对温度、气氛条件以及保温时间对固态脱碳的影响进行了综合概述,介绍了固态炼钢新工艺的研究进度,以及对未来前景的展望。     

高品质IF钢碳含量控制关键技术研究

针对攀钢某厂超低碳钢生产过程中存在的RH深脱碳能力弱、脱碳结束到钢液连铸过程增碳严重的问题,通过RH脱碳工艺参数进行优化,无碳钢包技术的综合应用,使IF钢成品的碳碳量得到了有效控制。     

白心可锻铸铁管路连接件生产技术的研究

研究开发了一种使用罩式电阻炉、采用气相脱碳法生产白心可锻铸铁管路连接件的先进技术。同时探讨了这种铸件的化学成分、熔炼工艺以及影响脱碳处理的诸因素。     

防脱碳涂层在U75V重轨钢生产中的开发与应用

为解决高碳含量的U75V重轨钢在加热过程中易出现严重氧化及脱碳而影响其力学性能的难题，通过对U75V重轨钢热物性能、脱碳特征的研究，考虑防脱碳涂层在加热过程的热膨胀系数和导热系数，采用以相变温度为分界点的分温度段设计理念，并结合氧化及脱碳特征分析了防脱碳涂层玻璃相、C平衡、固相致密烧结及综合热膨胀系数，有针对性地设计开发了防脱碳涂层。通过实验室实验调整了涂层组分，最后进行了工业现场试验验证。结果表明：所开发的防脱碳涂层在U75V重轨钢生产中的高温加热条件下，绝大多数情况下能保证钢坯脱碳层厚度在100μm以内，基本能实现零脱碳；未使用涂层的U75V重轨钢钢坯脱碳层厚度为270～550μm,大部分脱碳层厚度集中在450～550μm。采用防脱碳涂层，吨钢成本虽增加约16元，但在现有加热介质和加热工艺条件下，有效解决了U75V重轨钢加热过程中的脱碳问题。     

丙碳脱碳塔内件的改造—以MD型塔板代换散装填料

近年来,碳酸丙烯酯(丙酯)脱碳获得了相当规模的工业应用。但某些厂由于脱碳塔内件采用散装填料,气液分布欠佳,又易堵塞,影响了脱碳效率和气液通量。良渚化肥总厂的丙碳脱碳塔几经改动调试,见效不大,今年8月,由浙江工学院提供科技成果MD技术,厂校合作,以MD型塔板代换散装填料获得成功。生产实测表明,MD型塔板的通量可提高30％以上,传质效率可提高20％以上,操作稳定,是丙碳脱碳的最佳塔内件,值得推广应用。     

上钢五厂九车间采用浸酸法防止钢材表面脱碳

上钢五厂九车间生产冷拉棒钢,滚珠轴承钢户量约占总产量的三分之一。历年来滚珠轴承钢的表面脱碳是生产中的老大难问题。常因脱碳不合格而改规格,甚至发生用户退货事件,损失很大。酸洗 QC 小组成立后,根据国外资料关于“钢材浸磁酸后热处理,可以防止表面脱碳”的报导,采用正交试验法,摸索出符合车间生产条件的浸酸工艺。规定硫酸浓度控制在     

弹簧钢50CrV4加热气氛对表面脱碳的影响

研究了加热气氛对弹簧钢50Cr V4脱碳厚度的影响,分析了H_2O、CO_2、O_2的3种气体对弹簧钢50Cr V4脱碳层厚度的影响。以实际生产加热炉中的气氛为基准,采用了6种不同的气氛,分别改变H_2O、CO_2、O_2的摩尔浓度研究这3种气体对50Cr V4脱碳的影响。分析了6种气氛下H_2O、CO_2、O_2摩尔浓度与脱碳层厚度的关系。结论表明:H_2O、O_2的脱碳效果都要比CO_2明显。用数学模型及数据拟合的方法求出了脱碳影响因子,不仅验证了上述观点并且精确地确定了3种气体的脱碳作用强弱,3种气体脱碳影响因子分别为a(CO_2)=0.37,b(O_2)=1.63,c(H_2O)=0.86,其中CO_2的脱碳作用很弱。     

冶炼过程的脱碳速度对硅锰钢性能的影响

在第一拖拉机股份公司铸钢厂实际生产条件下,分析了冶炼生产,控制冶炼周期中的氧化脱碳速度可控制钢中氧含量的高低,试验结果表明,氧化脱碳速度控制为0.009￣0.012%C/min,钢液原始含氧量可控制在100 ppm以内,并保证钢液中的残余稀土含量,从而减少硫化物对硅锰钢性能的影响,可得到冲击功大于35J的硅锰钢。     

Surface decarburization behavior and its adverse effects of air-cooled forging steel C70S6 for fracture splitting connecting rod

Surface decarburization behavior and its adverse effects of air-cooled forging steel C70S6 for automobile engine fracture splitting connecting rod were investigated comprehensively by mechanical properties, microstructure and fracture morphology analysis. The results show that the surface decarburization in the outer surface of the fracture splitting at the big end bore and the micro-cracks in the decarburized layer are result in the uneven and spalling fracture surfaces of the waster connecting rod product. Besides, partial decarburization is produced between 900 °C and 1250 °C for heating 2 h, and decarburization sensitivity reach maximum at 1150 °C, but no complete decarburization forms for heating 2 h at 650-1250 °C. The decarburized depth follows a parabolic law with the increase of the heating time from 0.5 h to 12 h, and the decarburization sensitivity coefficient is 2.05×10^-5 m·s^-1/2 at 1200 °C. For the connecting rod manufacturing, surface decarburization must be under effective control during the hot forging process but not the control cooling process.     

FIB-SEM Sectioning Study of Decarburization Products in the Microstructure of HVOF-Sprayed WC-Co Coatings

The thermal dissolution and decarburization of WC-based powders that occur in various spray processes are a widely studied phenomenon, and mechanisms that describe its development have been proposed. However, the exact formation mechanism of decarburization products such as metallic W is not yet established. A WC-17Co coating is sprayed intentionally at an exceedingly long spray distance to exaggerate the decarburization effects. Progressive xenon plasma ion milling of the examined surface has revealed microstructural features that would have been smeared away by conventional polishing. Serial sectioning provided insights on the three-dimensional structure of the decarburization products. Metallic W has been found to form a shell around small splats that did not deform significantly upon impact, suggesting that its crystallization occurs during the in-flight stage of the particles. W₂C crystals are more prominent on WC faces that are in close proximity with splat boundaries indicating an accelerated decarburization in such sites. Porosity can be clearly categorized in imperfect intersplat contact and oxidation-generated gases via its shape.     

ZGMn13Cr2钢水韧处理中的脱碳行为

研究了不同水韧条件下ZGMn13Cr2钢的脱碳行为,分析了实际脱碳深度与理论计算之间的关系,并对传统的计算模型进行了修正.结果表明,水韧处理加热温度越高,保温时间越长,脱碳越严重.当加热温度为1000℃时,实际脱碳深度与理论脱碳深度相似;加热温度为1050℃和1100℃时,由于氧化反应的加剧以及碳化物的作用,实际脱碳深...     

国内外脱碳层深度测定方法标准综述

介绍了钢的脱碳产生机理和类型,国内外脱碳层深度测定方法标准,国家标准的变迁历程,研析和比较各种测定方法原理、特点和差异,介绍典型钢种的金相测定方法,提出规范有效脱碳层的测定方法,解决轴承钢、高速钢和钢轨用钢的脱碳层测定难题,有助于理解实施国内外脱碳层测定方法标准,方便国际钢铁贸易交流,推动钢的脱碳层控制和测试技术的发展与进步。     

电子探针面分析法测定钢的脱碳层深度

提出钢表层脱碳层深度测定的一种新方法,即电子探针面分析法.对热轧态高碳工具钢75Cr1、淬火齿轮钢20CrMnTi、冷轧退火低碳车厢板SH1100钢3个典型钢种完成脱碳层深度的测定试验,结果表明:对于珠光体-铁素体型中高碳钢的脱碳层深度测定,金相法测定值是电子探针面分析法测定值的77％左右;对于淬回火钢的脱碳层深度测定...     

Nb-V微合金化对弹簧钢60Si2MnA表面脱碳的影响

研究了Nb-V复合微合金化、加热温度和保温时间对弹簧钢60Si2MnA表面脱碳行为的影响,并运用Fick第二定律讨论了脱碳层深度与温度、时间之间的定量关系,探讨了Nb-V降低60Si2MnA表面脱碳敏感性的机理。结果表明,等温处理或等时处理,60Si2MnA的脱碳层深度的实测值和基于扩散方程的计算值具有较好的一致性,Nb-V复合微合金化可以明显降低弹簧钢60Si2MnA的脱碳敏感性。     

Microstructure of a nitrided steel previously decarburized

In this study the effects of a surface-controlled decarburization on the structure of a nitrided steel are analyzed. Samples of a quenched and tempered 42CrMo4 steel were decarburized by heating in air at different depths and submitted to gaseous nitriding. After decarburization and nitriding, the microstructure of surface layers was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The nitrogen and carbon profiles in the diffusion layers were determined by SEM equipped with a wavelength dispersive spectrometer (EPMA-WDS) and by glow discharge optical spectrometry (GDOS). The effect of nitriding was determined by microhardness measurements. Our results indicate that a previous decarburization only slightly affects the surface hardness, but reduces the conventional nitriding depth. The decarburization also favors the nitrogen take-up and produces increased nitrogen concentrations in the compound layer and in the narrow zone beneath it.     

高磁感取向硅钢的脱碳退火工艺

采用自主研发的热处理试验装置,完成高磁感取向硅钢27QG090实验室脱碳退火过程,利用蔡司显微镜和X射线衍射仪分析脱碳退火后试样的显微组织和宏观织构。结果表明,高磁感取向硅钢27QG090经实验室脱碳退火后的显微组织类型为铁素体,平均晶粒尺寸为30～40μm。宏观织构主要类型为α织构和α^*织构({114}〈481〉、{113}〈361〉等织构),还有微弱的高斯织构{110}〈001〉。经实验室研究选定的最优工艺为850℃脱碳退火7 min。采用该工艺在工业生产线脱碳退火后的宏观织构与实验室脱碳退火后主要织构类型相同。脱碳退火后平均晶粒尺寸为30μm左右时,铁损最低,为0.80 W/kg,磁感应强度可达到1.93 T。     

HVOF喷涂纳米结构WC-12Co涂层的组织结构分析

纳米结构WC-12Co涂层的研究目前已受到了广泛重视,对其组织结构及影响因素的研究有利于提高涂层性能.采用HVOF工艺制备了纳米结构、多峰结构及普通微米结构3种WC-12Co金属陶瓷复合涂层,并采用SEM、XRD等对粉末及涂层的显微形貌、组织结构进行了分析;探讨了粉末在喷涂过程中的氧化脱碳机理,并指出了与之相关的影响因素.结果表明:纳米结构WC-12Co涂层结构致密,孔隙率低,与基体结合状态良好;纳米粉末在喷涂过程中比微米粉末氧化失碳严重,并发生了不同的纳米晶粒的长大;纳米粉末在喷涂过程中的氧化脱碳程度不仅与喷涂工艺有关,还在很大程度上取决于粉末本身的结构特性.     

Effect of Decarburization on the Residual Stresses Produced by Shot Peening in Automotive Leaf Springs

The shot peening is used in the leaf springs manufacturing process for producing a compressive residual stress field (CRSF) at and near the surface that improves the fatigue resistance. The resulting CRSF is influenced by the surface ferrite thickness associated with the decarburization. Hence, this work aims to extend the knowledge on the influence of the decarburization on the CRSF for the given shot peening conditions. A study on the laboratory scale was conducted for an SAE 5160 steel grade used in the automotive industry. Next, specimens with different decarburization depths were treated using industrial shot peening, and the resulting CRSF was characterized. The CRSF was found to be influenced by the decarburization depth. It is assumed that the elastic deformation mechanism is predominant at low decarburization depths, followed by a zone in which both the elastic and plastic deformation have competing mechanisms that contribute to the CRSF, and at higher decarburization depths, the dominant mechanism is plastic deformation. The values for σ_srs and σ_mcrs decrease as the decarburized depth increases, and suitable CRSFs were obtained below a decarburization depth of 120 µm in industrial leaves. Furthermore, the prediction based on expressions correlating the measured variables was good in these leaves.