高碳钢SWRH72A线材轧制工艺的实验研究

采用热模拟技术研究高碳钢SWRH72A在热加工过程的金属现象和变化规律，建立了钢的连续冷却转变曲线(CCT)，并着重研究了高碳钢SWRH72A轧制中终轧温度、吐丝温度和冷却速度对钢的综合性能的影响，旨在建立合适的热轧工艺。     

原位观察铌对高碳钢珠光体相变的影响

 为了研究微合金元素铌(Nb)对高碳钢中珠光体相变的影响,在高温激光共聚焦显微镜下原位观察了不含铌和含铌高碳钢连续冷却过程中珠光体动态形核和长大行为。结果表明,在高碳钢中添加铌增加了珠光体形核点的数量,这是因为铌提高珠光体单位面积形核数量。同时,铌元素减慢珠光体长大速率是由于铌显著阻碍珠光体长大,但当铌质量分数超过0.014%后,阻碍珠光体长大速率的效果不再进一步增加。从以上结果可知,在高碳钢中添加铌促进珠光体形核,但是减慢珠光体长大速率。所以,为了更加准确地研究铌元素对珠光体相变的影响,选用不含铌及铌质量分数为0.027%的两种高碳钢,在Gleeble-3500热模拟试验机上进行与高温原位观察试验相同试验工艺的热膨胀试验。通过热膨胀试验发现,铌的添加增大过冷度,导致降低了珠光体相变温度区间,但是铌显著阻碍碳在奥氏体中的扩散系数,所以铌减慢珠光体长大速率。另外,铌减慢连续冷却条件下的珠光体相变动力学,推迟珠光体相变,从而降低珠光体相变速率,表明铌对珠光体长大的阻碍作用强于其对珠光体形核的促进作用。因此,在高碳钢中,铌元素的添加推迟珠光体相变。此外,铌的添加增大过冷度,使含铌高碳钢的珠光体片层细化,提高了含铌高碳钢的硬度,但在铌质量分数超过0.014%后,细化效果不再进一步增强。     

82A钢高速线材控制冷却工艺的优化

利用Gleeble 1500热模拟实验机测定了82A高碳钢(%:0.81C、0.50Mn、0.21 Si、0.007P、0.006S)0P5.5 mm线材在0.8～40℃/s冷却速度下的连续冷却转变(CCT)曲线,经与现场实测冷却曲线估算的实际相变温度拟合修正,得出符合生产实际的动态CCT曲线.结合高速线材控制冷却过程的基本模型,得出82A钢线材适宜的吐丝温度为910～930℃;相变过程最佳冷却速度为9～12℃/s.     

高碳钢盘条控制冷却工艺的探索与实践

根据高碳钢盘条索氏体化转变机理,对标准型斯太尔摩控制冷却线及高碳钢盘条的控制冷却工艺进行了探索,指出了该冷却线控制冷却的特点、问题和改进措施．     

高碳钢线材生产轧后冷却工艺探讨

本文介绍了当前高碳钢线材产品主要存在的质量问题,并提出了改进方法,认为轧后冷却工艺是高附加值高碳钢线材生产的关键。对于四种高碳钢线材轧后冷却方式进行了简述,对比了四种冷却方式的优缺点,认为斯太尔摩风冷线应用最广,但效果最小;其他三种工艺都是比较先进,其中EDC(Easy Drawing Conveyor)工艺在中国已经有应用,并取得了不错的效果。     

微合金化铌钒对高碳钢组织转变影响

研究了四种成分银钒微合金化(Nb 0～0.072%,V 0.09%～0.12%)高碳钢(0.70%～0.73%C)在900～1200℃的加热温度下的奥氏体晶粒长大规律,并采用热模拟试验机测定了连续冷却相转变行为,利用金相显微镜、硬度仪等研究了冷却速度对金相组织、硬度等指标的影响。结果表明:Nb和V含量增加可细化奥氏体晶粒尺寸,降低高温晶粒长大倾向,并且CCT曲线转变区向右下方移动,贝氏体和马氏体形成和结束点向低冷速方向扩大.结束点由8℃/s降低至3℃/s,样品硬度也随之增加。     

铌微合金化高碳钢的连续冷却转变

在Geeble-1500热／力模拟试验机上测定了铌微合金化高碳钢与普通高碳钢变形后的连续冷却转变曲线，分析比较了它们的组织演变规律。实验结果表明，与普通高碳钢相比，含铌高碳钢的转变温度较高，A P两相区的温度范围较大(在所测定的冷速下，温度范围均在100℃以上)，且在相同冷速下，先共析铁素体的数量明显增多，而奥氏体晶粒较小。在本实验条件下，当冷速大于10℃／s时，含铌高碳钢转变后的珠光体片层间距较小；在冷速大于30℃／s时，其基体中出现贝氏体组织。     

宽厚板高碳钢边部裂纹缺陷控制

分析了鞍钢股份有限公司鲅鱼圈钢铁分公司厚板连铸机高碳钢钢板边裂缺陷的产生原因,采取优化结晶器锥度和二次冷却强度、提高扇形段接弧精度和结晶器足辊接弧精度等措施后,高碳钢钢板边裂发生率仅为0.95%。     

相变过程温度场的有限元模拟

借助ＡＮＳＹＳ５．３采用ＡＮＳＹＳ参数化设计语言ＡＰＤＬ,模拟了高碳钢线材在斯太尔摩冷却线上冷却温度分布。结果表明,用连续转变曲线ＣＣＴ模拟比较接近于实际冷却过程,能够较准地模拟由于相变而引起的温度分布变分,为分析金属材料组织,性能变化提供参考。     

南钢高碳钢生产的质量控制

高碳钢是一种碳含量在0.6%到1.7%之间的特种钢材,它在我国目前的工业生产体系中占有举足轻重的作用。因此,在实现智能化、自动化、机械化的连续铸造工艺中,实现对产品质量的控制是国内钢铁企业发展的第一要务。对高碳钢的组成进行深入的研究,通过对高碳钢成分的认识,对其质量进行分析,以达到提高高碳钢的质量。     

Effect of Carbon Content on Mechanical Properties and Weather Resistance of High Performance Bridge Steels

The influence of carbon content on the mechanical properties of high yield strength bridge steel has been in-vestigated. The results show that the excellent mechanical properties and corrosion resistance are obtained for the steel with carbon content of 0.03%-0.05% (mass percent). According to the results, a new weathering bridge steel plate with carbon content of 0.045% (mass percent)has been developed. The appropriate controlled cooling process should be taken due to the results of CCT (continuous cooling transformation)and TTT (time-temperature-transformation)to ensure both microstructure and mechanical properties. CCT curve of the newly developed steel shows that when accelerated cooling speed is higher than 5℃/s, the intermediate transformation products can be formed. The TTT curve displays that the intermediate transformation temperature ranges from 600 to 530℃. Yield strength of the newly developed steels reaches 500 MPa, and their elongation and toughness are excellent.     

铬和铝元素对低碳贝氏体钢组织和性能影响

 低碳贝氏体钢通常需要添加一定量合金元素来提升性能,为了研究合金元素铬和铝在低碳贝氏体钢中的作用,以Fe-C-Si-Mn-Mo系贝氏体钢为基础,设计了单独添加铬元素和复合添加Cr+Al元素的3种低碳贝氏体钢,研究了铬和铝的添加对连续冷却处理低碳贝氏体钢显微组织、力学性能及贝氏体相变的影响规律。结果表明,连续冷却条件下,铬可以促进低碳贝氏体钢相变趋向于更低的温度区间进行,细化贝氏体组织,从而提高强度;铝可以促进贝氏体相变动力学,但对低碳贝氏体钢意义不大。同时,添加铝会使低碳贝氏体钢组织粗化,导致强度和伸长率同时下降。综合来看,复合添加铬和铝的优化效果不如单独添加铬,单独添加铬的低碳贝氏体钢强度达到1 623 MPa,伸长率为10.5%,结果可以为低碳贝氏体钢成分设计提供依据。     

On the structure and properties of high-nitrogen low-carbon non-austenitic steels

Phase transformations, when cooling and heating non-austenitic high-nitrogen low-carbon steels containing chromium and other alloying elements, as well as structure and mechanical properties of these steels were analyzed. It was confirmed that these steels have high temperature chromium diffusion controlled pearlitic type transformation and martensitic type transformation. Experimental high nitrogen steels after quenching and tempering provide mechanical properties of about the same level as high strength commercial alloyed steels. Features of nitrogen as an alloying element in steels discussed allow the supposition of a possible reduction of the consumption of nickel, manganese, molybdenum or tungsten in high strength alloyed steels.     

铬微合金化高碳重载车轮钢的连续冷却

 采用Gleeble 3500模拟试验机、金相显微镜和扫描电镜研究了两种含铬微合金高碳重载车轮钢的连续冷却组织转变规律，分析了冷速对组织及性能的影响。试验结果表明，铬元素含量高的高碳重载车轮钢的临界冷却速度低，淬透性高，珠光体域和珠光体片层间距小，洛氏硬度高；冷速为5.0、80、10.0℃/s时有少量的贝氏体和针状铁素体出现，且它们的体积分数随铬含量的增加而增加。     

Prediction of Continuous Cooling Transformation Diagrams for Dual-Phase Steels from the Intercritical Region

The purpose of the present work is the implementation and validation of a model able to predict the microstructure changes and the mechanical properties in the modern high-strength dual-phase steels after the continuous annealing process line (CAPL) and galvanizing (Galv) process. Experimental continuous cooling transformation (CCT) diagrams for 13 differently alloying dual-phase steels were measured by dilatometry from the intercritical range and were used to tune the parameters of the microstructural prediction module of the model. Mechanical properties and microstructural features were measured for more than 400 dual-phase steels simulating the CAPL and Galv industrial process, and the results were used to construct the mechanical model that predicts mechanical properties from microstructural features, chemistry, and process parameters. The model was validated and proved its efficiency in reproducing the transformation kinetic and mechanical properties of dual-phase steels produced by typical industrial process. Although it is limited to the dual-phase grades and chemical compositions explored, this model will constitute a useful tool for the steel industry.     

控轧控冷生产中高碳钢高速线材组织和性能的预测模型

建立了高碳钢高速线材在控制轧制和控制冷却生产中组织转变和力学性能的预测模型。该模型分为再结晶、相变、组织和力学性能四部分,分别考虑了在控轧控冷过程中的各种冶金现象。该模型的预测结果与现场实际测量结果比较一致,证明运用此模型进行组织和性能预测是可行的。     

低碳锰(铌)钢控轧控冷实验研究

通过TMCP研究了低碳锰钢和添加微量Nb的低碳锰铌钢的组织和力学性能的影响因素.研究了Nb对实验钢显微组织和力学性能的影响.Nb的添加能够细化铁素体晶粒,促进铁素体转变,对贝氏体形成有一定的抑制作用.相对低碳锰钢来说,铌的加入减少了贝氏体的体积分数,贝氏体强化效果减弱,钢的屈强比升高.通过增加冷速和降低卷取温度,可以使低碳锰铌钢获得一定量的贝氏体,综合性能较佳.低碳锰铌钢的主要强化机制有细晶强化、贝氏体相变强化和析出强化.     

Q690钢的过冷奥氏体连续冷却转变曲线

采用Formastor-F型全自动相变仪测定Q690钢的连续冷却转变曲线(CCT曲线),研究了Q690钢在不同冷却速度下的显微组织形态,分析了合金元素对连续冷却转变曲线的影响,通过对CCT曲线的测定为Q690钢热处理制度和控冷工艺提供理论依据.     

应用控轧控冷工艺开发低碳贝氏体高强度钢板

设计了强度级别为６８５ＭＰａ的工程机械用低碳高强度焊接用钢，利用Ｇｌｅｅｂｌｅ热模拟实验机研究了实验钢奥氏体高温变形行为、应变诱发析出行为和连续冷却相变行为。在此基础上利用实验轧机研究了轧制和冷却工艺参数对实验钢力学性能和显微组织的影响。结果表明，实验钢通过适当的控制轧制和控制冷却可以得到以细小的贝氏体为主的显微组织，达到强度和韧性的良好匹配。     

Influence of Mn Content and Hot Deformation on Transformation Behavior of C-Mn Steels

The hot deformation behaviors and the microstructural evolution of plain C-Mn steels with similar contents of C and Si but different contents of Mn have been investigated by compressive processing using Gleeble-1500 mechanical simulator.Influence of Mn and hot deformation on continuous cooling transformation of steels has been studied.The experimental results showed that deformation in austenite region accelerated transformation process,and the extent is dependent on the hot deformation and cooling conditions.The hot deformation would promote transformation process,but the increase of transformation temperature is dependent on Mn contents.The results have also shown that the effect of deformation on ferrite transformation becomes more obvious with the increase of Mn content at relatively low cooling rate.