残余元素对连铸坯和热轧板表面质量的影响

 通过扫描电镜、透射电镜和EDS分析,对残余元素对连铸坯和热轧板表面质量的影响进行了研究。试验结果表明,连铸坯氧化层中存在铜、砷和锡同时富集。热轧板基体层与氧化层界面存在铜、砷和锡富集,基体层铜、砷和锡含量高于氧化层铜、砷和锡含量。铜、砷和锡在γ晶界偏聚和铁优先氧化造成连铸坯中铜、砷和锡富集,加热炉二次加热加剧铜、砷和锡富集,铜、砷、锡向钢基体渗透扩散,恶化钢的塑性,导致中板表面微裂纹缺陷,分析了铜、砷和锡富集相对表面微裂纹的影响机理。     

钢中残余元素在连铸坯和热轧板中的富集行为

通过扫描电镜和X射线能谱分析仪(X-EDS)分析,对低合金钢种连铸板坯和热轧板中Cu、As和Sn的富集行为进行了研究.实验结果表明:连铸坯中氧化层和氧化层/基体层界面存在Cu、As和Sn元素同时富集现象;热轧板氧化层/基体层界面存在Cu、As和Sn元素富集相,基体层中Cu、As和Sn含量高于氧化层;热轧板晶界处Cu、As和Sn含量明显高于热轧板晶内;Cu、As和Sn在γ晶界偏聚和Fe的优先氧化造成连铸坯中Cu、As和Sn富集,加热炉的二次加热加剧Cu、As和Sn的富集程度,引起Cu、As和Sn向钢材基体渗透扩散,使钢的塑性恶化,导致中板大量表面微裂纹缺陷.分析了Cu、As和Sn富集相对表面微裂纹的影响机理.     

残余元素对低合金钢连铸坯高温延塑性的影响

 采用Gleeble 1500热模拟试验机测试了含有一定量残余元素Cu、As和Sn的低合金钢连铸坯的高温延塑性。低合金钢的第Ⅰ脆性温度区在ts～1340 ℃之间,第Ⅲ脆性温度区在920～730 ℃之间。由于钢中Cu、As和Sn等残余元素含量比较高,因此第Ⅲ脆性温度区比较宽,深度比较大。     

炼钢过程中的残余元素

本文讨论的主题是去除锑、砷、铜、铅、锌稀有元素。将残余元素的分压和其在钢中浓度的关系与典型的冶炼温度下铁的蒸汽压进行比较。只有铅、锌在铁不损失的情况下，可以以气体状态去除。而对于电炉底吹气体时，将有60％－90％的铅、锌可以去除。在钢包熔炼炉脱气过程中，估计会有25％－40％铅、锌被去除。研究表明，往钢液中喷入碳化钙去除例如锑、砷、锡残余元素是可行的。由大包底部喷入碳化钙的浓度与砷、锡浓度的涵数关系表明，在一定条件下，砷、锡可以被部分去除。利用硫化物从铁水中去除铜的实验数据也可以获得。利用这些数据可以估算出冰铜（主要成分为Na2S、FeS )去除铜的含量，然而，由于需要大量的反应物，除铜之后对钢液的去硫工作以及从钢液中除很难成为现实。研究利用冰铜、液态铝、反应气体从废钢中除铜的方法。实验过程成功地去除一定数量的铜，然而将它运用到生产中目前尚被怀疑。结论是：恰当的物料选择和机械清理是避免在随后的炼钢过程中去除残余元素的最佳方法。     

浅谈微合金元素对低合金钢热塑性的影响

介绍了几种微合金元素对低合金Ｃ－Ｍｎ钢热塑性的影响,分析了这些微合金元素影响热塑性的原因。结果表明,Ｃ－Ｍｎ钢中Ｃ含量在０．１８％左右时热塑性最低;Ｍｎ／Ｓ比低于５０时热塑性明显恶化;凡是能够在未变形前的１０００～１３００℃生成晶界析出物的元素,如Ｎｂ、Ａｌ、Ｓ特能降低钢,那些生成高温晶内析出物的元素,Ｔｉ、Ｃａ、Ｂ、ＲＥ等则能改善钢的热塑性。     

Influence of Residual Elements on Mechanical Properties of Two Carbon Steel Grades

Experiments were carried out to study the influence of residual elements on microstructure and mechanical properties of two carbon steel grades (i.e. 0.04% C and 0.20% C). The effect of residuals on the microstructure of the carbon steels was mainly to decrease ferrite grain sizes. The effect of residuals on tensile properties was mainly to increase yield and tensile strengths and to slightly decrease ductility, which reflected a combination of solid solution hardening by residuals and grain refinement. The 40 J notch toughness transition temperature (TT) was determined by fitting Charpy absorbed energies to a hyperbolic function and by finding the temperature corresponding to 40 J in the fitted curve; a statistical analysis was performed to ensure the repeatability of TTs defined by this procedure. After the step‐cooling heat treatment to maximize segregation, the 40 J TT of a 0.04% C steel with high Mn and Si contents increased by 28K and the 40 J TT of 0.20 % C steels with the highest residual level (0.085% Sn, 0.4% Cu and 0.4% Ni) increased by 24K, indicating that the upward shift of TT is small even for high levels of residuals. Grain boundary segregation was semi‐quantitatively analysed by Auger electron spectroscopy. Small amounts of Sn segregation were observed, most notably in the low‐C grade.     

TMCP工艺在低合金钢生产中的应用

根据济钢宽厚板厂现场实际情况,采取低碳低合金化和TMCP工艺相结合,成功开发了低合金高强度结构钢Q345E,该钢的各项力学性能符合国际标准要求。不仅为后续高强钢Q550D-Z、Q690D-Z合金减炼化提供参考数据,同时也为轧制同级别钢种去合金化成份提供合理的数据依据,保证该钢种采用合理的化学成份满足客户需求的力学性能。     

Dual Phase Heat Treatment of Low-Alloy Steel

Many researches on dual phase steel have beencarried out inthe past decades due to excellent prop-erties such as high work-hardening rate,highstrength and good ductility.Dual phase steels main-ly include three types of phase structure,ferrite-matensite,ma…     

Selective Oxidation of TWIP Steel During Continuous Annealing

The selective oxidation of Al‐free and Al‐added TWIP steel after full austenitic annealing at 800°C in a N₂ + 10%H₂ gas atmosphere with a dew point of ?17°C was investigated by means of transmission electron microscopy. A thick MnO layer was formed at the surface of Al‐free TWIP steel after the recrystallization annealing. Small crystalline c‐xMnO · SiO₂ (x > 2) particles and amorphous a‐xMnO · SiO₂ (x < 0.9) particles were found at the MnO/steel interface. In the subsurface, the Mn depletion resulted in the formation of a narrow ferrite layer. The annealing of the Al‐added TWIP steel also resulted in the formation of a thick MnO surface layer. At the MnO/steel interface, Kirkendall voids were formed between the amorphous a‐xMnO · SiO₂ (x < 0.9) oxide and crystalline c‐xMnO · Al₂O₃ oxide in the case of Al‐added TWIP steel. In the subsurface, a thin layer was depleted of Mn and the original austenite had transformed into ferrite. Internal oxidation of Al to Al₂O₃ and the formation of crystalline c‐xMnO · Al₂O₃ (x > 1) compound oxide particles were found to occur at the grain boundaries of the Mn‐depleted ferritic zone. The present contribution highlights the implications of the selective oxidation of TWIP steels for their processing in continuous annealing and continuous hot dip galvanizing lines.     

Effect of Residual Elements on Hot‐Crack Susceptibility of Austenitic Stainless Steel

After partial melting and solidification of cylindrical samples hot tensile tests were performed on austenitic stainless steels containing residual elements such as copper, tin and lead as well as calcium and magnesium. Using well controlled cooling conditions down to the testing temperature a radially solidified microstructure in the test zone of the samples was achieved. The testing material was prepared by remelting of base material from the industrial production and addition of single elements in the vacuum induction furnace. The maximum strength and the reduction of area were determined in the temperature range between liquidus and 1100°C. With regard to the reheating and hot rolling process some samples were thermally treated under industrial conditions. The ductility of the material at temperatures down to 950°C was tested and the effect of annealing was evaluated. Recommendations for material processing by continuous casting and hot rolling were derived from the tests performed.     

加热工艺对含铜钢表面氧化的影响

研究了加热工艺对含铜钢表面氧化的影响.结果表明,加热温度和加热时间对含铜钢表面氧化程度影响显著.含铜钢液态铜相出现在1 100～1 200℃的加热温度范围,而在1 000℃和1 300℃加热时,基体与氧化层界面处不出现液态铜相.加热温度为1 100℃时,液态铜相沿奥氏体晶界向基体的渗透能力比1 200℃时更强.高温加热时,随加热时间延长,含铜钢的氧化程度加重,同时也增强了液态铜相向基体的渗透.加镍可有效防止含铜钢在高温过程中形成液态铜相,避免铜发生热脆.     

Si对含铜钢表面高温氧化后铜元素富集的影响

研究了Si元素对抑制含铜钢高温氧化后表面铜元素富集的影响。结果表明:添加Si元素使合金氧化后形成较多内氧化产物2FeO.SiO2,该氧化物在生长过程中对基体局部区域形成包裹,可割断液相铜的扩散途径,降低富铜相中Cu的浓度,有利于减轻含铜钢高温氧化后基体表面铜元素偏聚,但同时会导致合金在1 150℃以上高温区抗氧化性能减弱。     

稀土对渗铝HK40耐热钢氧化性能的影响

采用 OM、SEM、EDX及 XRD等仪器设备 ,研究了经渗铝和稀土渗铝处理的 HK40耐热钢在 10 0 0℃、110 0℃、12 0 0℃空气中氧化的行为。发现经渗铝和稀土渗铝处理的 HK40耐热钢试样 ,其氧化动力学呈抛物线规律 ,经稀土渗铝处理后的试样 ,其氧化膜的塑性和粘附性得到改善 ,抗氧化性能有所提高     

鞍钢低合金钢及微合金钢生产与开发

为着阐述鞍钢低合金钢及微合金钢的生产与开发,首先回顾了我国特别是鞍钢的低合金钢及微合金钢的发展历程,接着又说明近20年来共生产低合金钢两干多万吨,“八五”期间生产了117种微合金钢,共计68万多吨,为我国经济建设和发展的需求及替代进口作出了较大的贡献。近几年为满足经济建设的急需,鞍钢高度重视技术改造,采用先进的生产工艺,已经为技术改造和设备配套投资10多亿元,同时又锻炼和培养了一支高素质高水平的技术队伍,为今后鞍钢在扩大低合金钢微合金品种、提高质量、促进高附加值产品的开发与生产,提高产品竞争力等,奠定了良好的基础。     

钢中残余元素对CSP产品质量的影响

简要论述了钢中残余元素对CSP产品质量和性能的影响及相关控制措施,包括钢中残余元素的来源和含量,板材中残余元素Cu等含量与边裂的关系;板材中残余元素的偏析;残余元素过多可导致冷轧板卷酸洗不净、表面发暗等现象;残余元素对板卷性能如抗腐蚀性能的影响等。提出了钢铁业要做大做强．必须提高钢水的纯净度和合理控制钢中残余元素含量的措施。