影响中厚板轧制终轧温度的因素及其控制

结合中厚板轧制特点,给出了中厚板轧制温度的计算模型,模型考虑了热辐射和对流、高压水除鳞、轧辊的热传导和塑性功对轧件温度变化的影响.分析了待温时间、轧制速度、出炉温度和轧制道次对终轧温度的影响,为中厚板轧制温度控制提供了依据.     

Ti微合金化Q355B组织和性能分析

分析了厚度和卷取温度对Ti微合金化Q355B组织和性能的影响。研究表明:在相同成分体系下,精轧温度850℃,卷取温度620℃时,在厚度3.0～8.0 mm范围内,强化机理一致,厚度的增减对性能影响不显著;对厚度规格15.75 mm采用终轧温度810℃,卷取温度不同时,强化机理发生变化,在620℃附近时,Ti的沉淀强化起到显著作用。     

铁素体轧制工艺对超深冲钢织构的影响

通过控制轧制过程中的粗轧终轧温度、精轧终轧温度及成品板的厚度,了解轧制过程中工艺参数对织构的影响及轧制过程中织构的演变规律。研究表明,当粗轧终轧温度从923℃降低到855℃时,{111}∥ND织构增强,有利于板材的最终性能;当精轧终轧温度由810℃降低到791℃时,不利的{113}110织构强度明显减弱,r值基本不变,有利于获得深冲性能优良的板材;当板厚由4.0 mm减薄到3.0 mm时,取向织构无明显变化,而相应的冷轧退火板,r值升高,r90达到3.2以上,|Δr|降低到0.08。     

20MnSi钢筋热连轧及轧后分级控冷过程温度变化模拟

 建立温度计算模型针对22 mm和28 mm规格20MnSi棒材热连轧及控制冷却过程温度场进行了计算机模拟分析,获得了棒材精轧及轧后分级控冷过程的温度变化规律。对轧制圆钢和螺纹钢筋不同条件下成品道次温度变化特点进行了研究。研究结果是,轧制22 mm和28 mm规格20MnSi螺纹钢筋时的终轧温度比轧制相同规格圆钢时显著升高。轧制螺纹钢筋时精轧末道次轧材表层形成螺纹出现较大的局部应变量和应变速率,由此产生大量变形热是终轧钢筋表层急速升温的根本原因。与轧制圆钢相比,为完成同等控冷效果及有效控制轧后组织性能,20MnSi螺纹钢筋精轧后第1水冷段的换热系数明显较高,因此需要相应采用较大的冷却水量。     

终轧温度对GCr15轴承钢网状碳化物析出的影响

研究了终轧温度(750～900℃)和成品规格(Φ12 mm和Φ5.5 mm)对GCr15轴承钢网状碳化物析出的影响。结果表明,当轧制规格为Φ12 mm、终轧温度为800℃时,碳化物网状级别最低,为1.5,终轧温度降至750℃时,碳化物网状级别增加至2.0;当轧制规格为Φ5.5 mm、终轧温度为850℃时,碳化物网状级别最低,为1.5,终轧温度在800℃时碳化物网状级别又升高至2.5。小规格轧材终轧温度过低,不利于网状碳化物析出的抑制,最佳终轧温度与轧制规格有关。     

轧制工艺对09CuPTiRE钢板韧性的影响

研究了终轧温度和终轧压下量对10min厚09CuPTiRE耐大气腐蚀钢板冲击韧性和断口形貌的影响。结果表明：终轧温度840℃、终轧压下量1mm时，该钢材断口形貌韧性特征和冲击韧性均比终轧温度890℃、终轧压下量1．5mm的钢材显著改善，因此终轧温度比终轧压下量对钢冲击韧性和断口形貌影响更大。     

冬季20g钢板性能合格率低的原因分析

冬季20g钢板时效冲击性能受气温的影响较大,从而直接影响到钢板性能合格率,对此我们用金相分析方法,找出影响时效冲击性能的因素:终轧温度偏低,冷却速度控制不当。为此提出:终轧温度的控制按厚度<16mm为上限,厚度>16mm的取下限。为了控制冷却速度将12～14mm厚度的铜板全部实行堆冷,但温度必须严格控制。     

中厚板冷却过程高精度温度模型

实现高满意度轧后冷却控制目标必须依赖于轧后冷却过程控制系统高精度的温度场计算模型。以钢板内部热传导、空冷及水冷换热系数为主要研究对象,建立了轧后冷却数学模型,回归了空冷和水冷换热系数,采用Crank-Nicolson有限差分法求解钢板温度场。将该模型嵌入到国内某中厚板厂轧后冷却控制系统,对不同钢种不同厚度钢板进行轧后冷却试验,试验结果表明,实际终冷温度和目标终冷温度偏差±10℃的命中率在90%以上,很好地实现了冷却过程温度控制。     

热连轧机带钢卷取温度影响因素仿真分析

针对带钢冷却特点,建立了带钢瞬态热传导仿真模型,采用有限差分法对1800mm热连轧机带钢终轧速度、带钢终轧温度、冷却水温度等因素对带钢层流冷却后温度的影响进行了仿真分析。得到的结果对于认识热轧带钢卷取温度的变化规律具有一定的应用价值。     

控轧控冷工艺对HP345屈强比影响的研究

通过控轧控冷工艺试验对HP345的屈强比影响进行了研究。结果表明,终轧温度和卷取温度对HP345钢的屈强比都有较大的影响,降低终轧温度和卷取温度,均使HP345的屈强比升高;卷取温度为650℃时,屈强比明显降低;而卷取温度降至580℃时,屈强比明显升高;卷取温度在610℃～630℃区间变化时,屈强比较低而且变化不大,同时钢具有较高强度。     

中厚板厂薄规格钢板轧制技术开发

通过分析影响薄规格钢板生产的因素,如精轧机轧制温度控制、板形控制、厚度控制等,开发出批量生产薄规格钢板的技术措施,如优化加热炉温度控制,提高精轧机温度保障能力;优化精轧机厚度自动控制系统的控制程序,实现薄规格钢板高精度厚度自动控制;优化精轧机辊型和轧制策略,提高板形控制能力等。成功开发出6 mm×3 000 mm极限薄规格钢板,并具备了薄规格钢板批量生产能力。     

Q345E- Z35�غ����з�

Billet with cross section of 350mm??2320mm was rolled to Q345E- Z35 with cross section of 100mm??2360mm. Different finishing rolling temperatures and re- reddening temperatures were tested with deformation higher than critical that of dynamic recrystallization and l/h??0. 53 during rough rolling. The results show that when finishing temperature of final finishing stage is about 780?? and re- reddening temperature is about 610??, the produced steel plate has excellent mechanical properties and lamellar tearing resistance.     

中厚板轧制过程的头尾温度差变化规律

针对中厚板轧制过程头尾部分温度差的变化规律进行分析,基于可逆轧制特点,计算不同道次头尾轧制时间和间隙时间的变化特点,重点研究厚度对头尾温度差的影响,得知,对于薄规格钢板,连续轧制过程钢板的累计头尾温差一般不超过7℃,对于30mm以上厚规格钢板累计头尾温度差不超过3℃。这个数值对轧制力设定和TMCP工艺的制定影响较小,不需要特殊进行考虑。同时转钢操作和待温处理不会恶化钢板头尾温度差异。     

精轧和吐丝温度对SCM435线材氧化铁皮物相结构的影响

线材的氧化铁皮起着保护线材免锈蚀的作用,但是也需要在酸洗时容易除去。影响铁皮除去或结合力的主要是铁皮的厚度和其物相结构。通过对不同轧制条件下的氧化铁皮厚度、物相结构进行检测分析,研究了精轧温度和吐丝温度对φ12 mm SCM435氧化铁皮物相结构的影响。研究表明,随着精轧温度或吐丝温度的升高,SCM435线材的氧化铁皮厚度均会增加,且在800-900℃短时间就会生成较厚(约20μm)的氧化铁皮;由于Cr的氧化选择性,精轧温度在870℃以上,吐丝温度在810℃以上时,随精轧温度或吐丝温度升高,氧化铁皮中FeO比例提高;但是吐丝温度高于860℃后,物相结构的变化趋缓,FeO的比例变化不大。     

Independent integration practice on revamping 4200/3500 mm medium and heavy plate rolling mill of Bayi Steel in terms of process and make-up equipment

This study systematically reviews and summarizes relocation and revamping project of medium and heavy plate rolling mill in Bayi Steel.After detailed analysis was made on the main deficiency and problems of the original production line of Pudong Steel,systematical integration and improvement for the process and equipment were carried out accordingly.Through innovative practice of integration,Baosteel Engineering has greatly improved the technical process and equipment make-up,as well as the grades and quality of the products.The original man-operating line is redesigned into an automatic system controlled by Level 2 computer,reaching the advanced technical level of home-made medium and heavy plate production line in recent years.The project is constructed in two phases;The original product mix of Pudong Steel is maintained as much as possible in Phase I.After 3 500 mm single stand finishing mill is put into operation, capacity of hot- rolling medium and heavy plate reaches 650 000 t/a,with the maximum thickness at 40 mm.Equipment or facilities are reserved for production of pipeline steel and other grades.Pipeline steel, vessel plate,wind power plate and other TMCP and heat treatment products are projected in PhaseⅡ.After 4 200 mm roughing mill and its matched facilities are put into operation,capacity of hot-rolling medium and heavy plate will reach 120 000 t/a,with the maximum thickness at 80 mm.Through the optimization of process equipment and its function,the relocated medium and heavy plate mill production line has reached advanced level among similar domestic mills.The prominent achievements of the project are the revamping of thickness control system of the finishing mill and the newly installed shape control system.Automation control of the whole line is realized.     

Heat Transfer During Quenching by Plate Roller Quenching Machine

For plate quenching on a roller quenching machine, heat transfer process is investigated. According to the practical online experiment of plate center temperature, average heat transfer coefficient under different conditions and temperature fields are analyzed by numerical simulation. The results show that, at the water temperature of 15 ℃, the instantaneous maximum quenching cooling rate is 17.6 ℃/s for the plate of 50 mm in thickness in roller quenching process. In the temperature range of 400-850 ℃, the maximum is 12.1 ℃/s. With the plate surface temperature decreasing, surface heat transfer coefficient increases at first, and reaches the maximum value of about 15 000 W/(m~2·K), and then decreases. The calculated heat transfer coefficients are applied to analyze plate temperature field of different thicknesses, and the difference between the calculated and measured temperature is less than 5%.     

精轧工艺对汽车大梁钢氧化铁皮厚度的影响

为了降低热轧汽车大梁钢的氧化铁皮厚度,采用模拟方法分析了热轧工艺参数对表面氧化铁皮厚度的影响。模拟分析结果表明:精轧入口温度从1 080℃降低到1 040℃时,氧化铁皮厚度约降低8μm,终轧温度从890℃降低到850℃时,氧化铁皮厚度降低2.5μm;轧制速度从3.5m/s提升到6.5m/s时,氧化铁皮厚度降低了约7μm;总压下率对氧化铁皮厚度的影响较小,当压下率从74%增加到87%时,氧化铁皮的厚度降低约2μm;在总压下率一定的条件下,增加上游机架压下率会增加氧化铁皮厚度,而增加下游机架压下率则会降低氧化铁皮厚度。     

A Study of Thickness Effect on Fatigue in Thin Welded High Strength Steel Joints

It is well known that the fatigue strength of welded joints decreases when plate thickness increases. This decrease in fatigue strength is known as the thickness effect. In many standards for fatigue design the thickness effect is taken into account for joints with plate thickness typically greater than 25 mm. Previous work has mainly been focused on joints with plate thickness between 12‐200 mm. Less attention has been paid to thinner joints. Published investigations on joints with sheet thickness 2‐12 mm show an increase of fatigue strength with decreasing sheet thickness. In the present study results from constant amplitude fatigue testing of non‐load carrying welded joints in high strength steel of thickness 3‐12 mm are presented. The results show an increase in fatigue strength with decreasing sheet thickness down to 3 mm. Fracture mechanics calculations confirm the test results.     

高强韧性海洋平台用E550钢板生产工艺研究

介绍了E550钢板的主要生产工艺和技术难点,通过理论分析设计了E550的成分体系,采用Thermal-Calc和经验公式,获得了其热力学相图和相变点温度等热力学数据。根据E550的热力学特性,设计了两阶段轧制工艺,精轧的终轧温度控制在再结晶温度附近,利用奥氏体再结晶充分细化晶粒。淬火奥氏体化温度选择为920℃,回火温度设计为630℃,利用碳化物的析出强化效果和缺陷密度变化的位错强化获得良好的强韧性匹配。50 mm厚钢板的淬火态1/4厚度处的微观组织为马氏体,中心的组织为马氏体和少量贝氏体的混合物。回火热处理后,马氏体板条界面减少,碳化物在马氏体板条界面析出,钢板1/4到中心的组织均匀化。30和50 mm厚E550钢板的力学性能达到了船级社标准要求,并有较大的富裕量。热输入能量为15和50 kJ/cm焊接后,钢板具有良好的强度性能,熔合线和热影响区的冲击功较高。     

中厚板头尾厚度超差原因分析

基于四辊中厚板轧机,分析了温度、头部沉入、AGC系统、压力传感器和展宽比对中厚板头尾厚度超差的影响.头尾温度过低对厚度偏差影响较大,它使得钢板塑性系数增加,造成钢板头尾厚度增厚,这种影响每道次都存在并与下一道次的结果进行叠加,增大厚度超差的可能性.头部沉入对头部厚度的影响可通过沉入补偿进行消除.咬入阶段AGC系统不投入的影响可通过减小咬钢速度的方法进行部分消除.展宽比过小会加剧头尾厚度增厚,展宽比过大会缓解头尾增厚的趋势.这些分析为今后钢板头尾厚度超差的控制方法提供一定的理论依据.