Effect of Coiling Temperature on the Evolution of Texture in Ferritic Rolled Ti-IF Steel

The effect of coiling temperatures on the evolution of texture in Ti-IF steel during ferritic hot rolling, cold rolling and annealing was studied. It was found that texture evolution at high temperature coiling is absolutely different from that at low temperature one. The hot band texture includes a strong α-fiber as well as a weak γ-fiber after ferritic hot rolling and low temperature coiling. Both of them intensify after cold rolling and a γ-fiber with peak at {111}〈112〉 is the main texture of annealed samples. However, the main component of the hot band texture after high temperature coiling is v-fiber. After cold rolling, the intensity of γ texture reduces; α fiber （except {111}〈110〉 component） intensifies and a strong and well-proportioned γ-fiber forms in the annealed samples.

Effects of final rolling temperature and coiling temperature on precipitates and microstructure of high-strength low-alloy pipeline steel

The strength-to-weight ratio is an important property of high-strength low-alloy(HSLA)steel in pipeline,whose precipitation strengthening can be improved.The final rolling temperature(FRT)and coiling temperature(CT)are the key process parameters in the control of precipitates and microstructure.Continuous cooling rate was fixed at 10℃/s,and the effects of deformation and coiling temperatures on precipitates and microstructure of Ti-Nb microalloyed HSLA steel were investigated through thermo-mechanical controlled processing on Gleeble 3500.The microstructure is mainly acicular ferrite with high density dislocation and several microns scale.The size and volume fraction of the precipitates were studied under transmission electron microscopy.The results showed that the diameter of the precipitates was in the range between 4 and 240 nm.The optimized combination of parameters is FRT of 820℃and CT of 550℃,and the volume fraction of precipitates obtained under this process is 0.59%.

Simultaneously Improving Mechanical Properties and Stress Corrosion Cracking Resistance of High-Strength Low-Alloy Steel via Finish Rolling within Non-recrystallization Temperature

The effect of hot rolling process on microstructure evolution,mechanical properties and stress corrosion cracking(SCC)resistance of high-strength low-alloy(HSLA)steels was investigated by varying the finish rolling temperature(FRT)and total rolling reduction.The results revealed granular bainite with large equiaxed grains was obtained by a total rolling reduction of60%with the FRT of 950℃(within recrystallization temperature T_(r)).The larger grain size and much less grain boundaries should account for the relatively lower strength and SCC resistance.A larger rolling reduction of 80% under the same FRT resulted in the formation of massive martensite-austenite(M/A)constituents and resultant low ductility and SCC resistance.In contrast,a good combination of strength,ductility and SCC resistance was obtained via 80% rolling reduction with the FRT of 860℃(within non-recrystallization temperature T_(nr)),probably because of the fine grain size and M/A constituents,as well as a high density of grain boundary network.

Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated. The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or ＂warm rolling＂. The microstructure was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy, and X-ray diffraction was used to characterize the texture evolution processes. The results showed that as compared to conventional hot rolling process, the warm rolling has led to the refined and homogeneous microstructure and uniform recrystallization texture along γ-fiber in final sheets, indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

Effect of Finish Rolling Temperature on Microstructure and Mechanical Properties of High Grade Pipeline Steel

The correlation among finish rolling temperature (FRT),microstructure and mechanical property of the high grade pipeline steel was investigated in this study.The microstructure of the steels with different finish rolling temperatures was observed with scanning electronic microscope (SEM) and transmission electronic microscope (TEM).The martensite/austenite (M/A) islands distribution was fixed by colour metallography,and the mechanical properties of the steels were tested with quasi-static tensile testing machine.The result shows that the fraction of M/A island increased with the finish rolling temperature decreasing,and when the finish rolling temperature is 800℃,the mechanical properties are the best.

Mathematical model for cooling process and its self-learning applied in hot rolling mill

Control precision of coiling temperature is one of the key factors affecting the profile shape and surface quality during the cooling process of hot rolled steel strip.For this reason,the core of temperature control precision is to establish an effective cooling mathematical model with self-learning function.Starting from this point,a cooling mathematical model with nonlinear structural characteristics is established in this paper for the cooling process of hot rolled steel strip.By the analysis of self-learning ability,key parameters of the mathematical model could be constantly corrected so as to improve temperature control precision and adaptive capability of the model.The site actual application results proved the stable performance and high control precision of the proposed mathematical model,which would lay a solid foundation to improve the steel product qualities.

大口径厚规格X80管线用钢板热轧工艺研究

在X80管线钢热轧板材合金化成分体系设计的基础上,利用中试冶炼轧制平台开展X80管线钢板热轧工艺研究。结果表明:X80管线钢板压下率大于26%并待温60 s时,奥氏体晶粒发生再结晶,获得明显细化的再结晶组织;卷取温度为400℃时,M-A岛细而弥散地分布于基体中,与之相对应的DWTT韧性较优。综合考虑X80管线钢化学成分的合金化特点,以及板卷屈服强度、屈强比、夏比冲击功和DWTT剪切面积百分比的理想控制水平,为工业化试制选择了(400±35)℃的卷取温度。

SPA-H耐候钢轧制工艺研究

介绍了新钢热轧SPA-H耐候钢的轧制工艺研究情况。通过调整精轧终轧温度及卷取温度,使钢材的性能满足了生产要求。

卷取温度与冷却速率对含铌热轧双相钢显微组织与拉伸性能的影响

将含铌双相钢在相同工艺参数下进行热轧并分别以冷却速率60℃·s^(-1)一次水冷至610℃或不同冷却速率两段式水冷至461,434,410℃后进行卷取,分析了卷取温度和冷却速率对热轧双相钢显微组织和拉伸性能的影响。结果表明:4种工艺下热轧双相钢组织均主要由铁素体和马氏体构成,在卷取温度为461℃以下时还出现了贝氏体;随着卷取温度的降低,马氏体含量降低,贝氏体依次呈分散颗粒状、聚集颗粒状和板条状,热轧双相钢的屈服强度增大,抗拉强度先减小后增大,屈强比增大,断后伸长率先增大后减小;当以一次和二次冷却速率分别为53,79℃·s^(-1)两段式水冷至461℃进行卷取后,热轧双相钢的拉伸性能最佳,平均屈服强度、平均抗拉强度、平均断后伸长率分别为459 MPa,591 MPa,35.63%。

某CSP线生产热轧双相钢DP600终轧温度的研究

针对某CSP短流程生产线的特点,设计了中温卷取型600 MPa级热轧双相钢的化学成分,测定了其动态CCT曲线。研究了终轧温度对热轧板的显微组织与力学性能的影响。结果表明:终轧温度在821~858℃变化时,热轧板的显微组织均由铁素体和马氏体组成。随着终轧温度的升高,铁素体的体积分数略微增大,由84.60%增大到85.14%,而铁素体的晶粒尺寸增大较为明显,由5.07μm增大到5.97μm。不同终轧温度下,抗拉强度均达到600 MPa以上,伸长率均在24.0%以上,应力-应变曲线均表现为连续屈服。但随着终轧温度的升高,热轧板的屈服强度呈现降低趋势,当终轧温度达到858℃时,热轧板的屈服强度(322 MPa)未达到DP600钢的性能要求(325 MPa以上)。结合某CSP线的特点及DP600钢的性能要求,生产DP600钢合理的终轧温度规程应为(830±15)℃。

基于DSCCR生产工艺的终轧温度对轧制过程中低碳钢组织与性能影响分析

基于东华连铸连轧生产线(Donghua steel continuous casting rolling,DSCCR)分别进行终轧温度为880,820℃和780℃的热轧实验,研究终轧温度对低碳钢组织和性能的影响。采用光学显微镜(optical microscope,OM)、扫描电子显微镜(scanning electron microscope,SEM)、电子背散射衍射(electron backscatter diffraction,EBSD)技术等表征手段观察分析了不同终轧温度下热轧带钢的微观组织,同时对热轧带钢的拉伸力学性能进行测试和分析,对比分析不同终轧温度条件下热轧带钢的屈服强度、抗拉强度和伸长率的变化情况。此外,还对不同终轧温度下热轧带钢的氧化铁皮厚度进行测定。结果表明:随着终轧温度的降低,带钢屈强比及伸长率都降低,屈强比由880℃时的0.8~0.81降低至780℃时的0.75~0.79,伸长率由880℃时的40%下降到780℃时的27%,应变硬化指数n值也从880℃时的0.22下降到780℃时的0.17;同时,对不同终轧温度下热轧带钢氧化铁皮进行观察分析,随着终轧温度的降低,氧化铁皮厚度减小,氧化铁皮厚度由880℃时的10.2μm下降至780℃时的8.8μm,降幅达13.7%,氧化铁皮的降低可提高后续酸洗效率,降低酸洗消耗。

终轧温度对建筑用Q460GJC结构钢组织与力学性能的影响

通过Gleeble-3500试验机模拟了Q460GJC钢的不同温度的终轧轧制,采用OM、SEM、拉伸试验等研究了不同终轧温度对Q460GJC钢组织和性能的影响。结果表明:随着终轧温度的升高,Q460GJC钢的屈服强度逐渐下降,抗拉强度总体变化不大,屈强比不断下降,终轧温度860℃轧制的Q460GJC钢的屈强比最低,为0.72,其屈服强度和抗拉强度分别为477.5 MPa和663.1 MPa。随着终轧温度的升高,Q460GJC钢中M/A岛尺寸和数量逐渐减少,形貌从块状逐渐转变为细小条状,分布也更为均匀。

冷轧无取向硅钢阻尼厚度波动成因分析及控制

通过分析热轧、冷轧全流程工艺参数,研究了冷轧无取向硅钢阻尼厚度波动的产生原因。结果表明,带钢酸洗不净,氧化铁皮残留带钢表面导致冷轧轧机打滑,是造成阻尼厚度波动的直接原因。通过优化热轧卷取温度以降低酸洗难度,优化冷轧拉轿工艺、酸洗速度和轧辊粗糙度来提高酸洗质量,进而阻尼厚度波动问题得到有效解决。

高性能稳定性和高r值Ti-IF钢的生产实例

唐钢高强汽车板有限公司开发Ti-IF钢初期,产品出现性能稳定性差、r值波动大的缺点,后通过全流程一贯化管理,实现Ti-IF钢的性能稳定控制,r值优良。具体措施包括:炼钢过程控制微合金元素;热轧过程控制低温加热、高温终轧、高温卷取;冷轧过程控制大的压缩比,并高温退火。

耐腐蚀低碳钢控温控轧工艺研究

文章对耐腐蚀低碳钢生产工艺进行了概述,在控温控轧工艺研究中,主要包括控温控轧工艺设备结构设计、加热→除磷工艺研究、粗轧轧辊组间距控制研究、粗轧→除磷工艺研究、精轧阶段工艺研究、耐腐蚀低碳钢控温控轧工艺的有益效果等。研究表明,通过控制面板控制精轧视觉检测器,检测经过单个精轧轧辊组后的低碳钢钢板上的裂纹特征,并检测调节后精轧装置功率的轧辊转速比,根据转速比判定精轧装置是否出现故障;通过控制面板进行压力控制并检测精轧装置实际轧制压力值,然后据此压力判定精轧装置是否出现故障,可以逐步增加低碳钢生产效率,杜绝设备故障造成的低碳钢钢板的无效轧制。

终轧温度和卷取温度对低碳铝镇静钢性能的影响

通过现场试验和实验室检验，研究了终轧温度和卷取温度对低碳铝镇静钢性能的影响。结果表明，热轧过程中终轧温度偏低，导致低碳铝镇静钢热轧商品卷延伸率偏低，延伸率与卷取温度关系不大，但冷轧成品的性能与终轧温度和卷取温度却密切相关。

待温厚度与终轧温度对X80管线钢组织中马氏体/奥氏体岛的影响

利用光学显微镜、扫描电镜及透射电镜分析了经不同工艺热轧得到的22 mm厚X80管线钢中马氏体/奥氏体(M/A)岛的形貌及分布。结果表明:M/A岛的形貌及分布与待温厚度和终轧温度密切相关,适当增加待温厚度,降低终轧温度有利于细化M/A岛的组织,减小M/A岛的尺寸,降低M/A岛的体积分数,使X80管线钢的落锤性能得到改善。

宝钢SPHC出口钢卷“腰折”的消除

在板材 (或带钢 )的生产过程中 ,如果板材在卷取条件下退火 ,当开卷时 ,在板材的内外表面会经常出现腰折现象 ,在不改变 SPHC出口钢卷的现有成分和不增加生产工序的前提下 ,通过改变终轧温度、冷却介质和卷取温度来消除 SPHC出口钢卷的腰折。经生产现场验证 ,采用 82 0℃终轧、喷雾冷却、5 2 0℃卷取的工艺 ,SPHC出口钢卷在精整线上开卷时 。

热轧工艺对高碳带钢的组织和力学性能的影响

研究了热轧关键工艺参数对高碳带钢的组织和力学性能的影响。结果表明,终轧温度对屈服强度影响较显著,终轧温度由870℃~880℃提高至900℃~910℃时,50CrV4的珠光体片层间距减小约20%,屈服强度和抗拉强度分别增加91MPa和30MPa;卷取温度由620℃~630℃提高至690℃~700℃和钢卷加保温罩缓冷,分别使65Mn和50Mn2V的珠光体片层间距增大接近1倍,屈服强度和抗拉强度均降低200MPa以上,塑性提高5%~6%。

终轧温度和卷取温度对汽车大梁钢氧化铁皮特征的影响

通过SEM(扫描电镜)和IPP软件研究了不同终轧温度和卷取温度下汽车大梁钢的氧化铁皮厚度、微观结构。结果表明,终轧温度为800~920℃时,汽车大梁钢的氧化铁皮微观结构均为残余FeO+先共析Fe3O4,随着终轧温度的升高,氧化铁皮平均厚度增加,Fe O比例增加,先共析Fe3O4比例降低。卷取温度为530~650℃时,氧化铁皮组织中存在共析组织(Fe3O4+Fe),随着卷取温度的升高,汽车大梁钢的氧化铁皮平均厚度增加,FeO比例增加,先共析Fe3O4比例增加,共析(Fe3O4+Fe)比例降低。