Ti—IF钢铁素体区与奥氏体区轧制组织性能的差异

在实验室条件下分别进行了Ti—IF钢铁素体区与奥氏体区热轧、冷轧和退火试验。通过拉伸试验、金相观察、织构分析等比较了两种不同轧制工艺下的组织性能。试验结果表明,奥氏体区轧制下Ti—IF钢的屈服强度为157MPa,抗拉强度308MPa,延伸率49．1％,11值0．26,r值2．03;铁素体区轧制Ti—IF钢的屈服强度127MPa,抗拉强度306MPa,延伸率49．5％,n值0,31,r值2．43。与奥氏体区轧制相比,铁素体区轧制具有更低的屈服强度,高的n值,高的r值。     

铁素体轧制生产超深冲冷轧板

通过铁素体轧制生产超深冲冷轧Ti-IF钢的工业试验,研究了化学成分、工艺制度对热轧IF钢金相组织、织构和第二相粒子析出的影响,分析了热轧IF钢再结晶状态与产品性能的关系,阐述了提高冷轧Ti-IF钢深冲性能的生产控制要素.试验结果表明:在采用适宜的成分、低的加热温度、高的卷取温度和铁素体区强润滑轧制时,热轧板具有粗大的二相粒子和强的{111}织构;与常规轧制相比,冷轧板的r值在横向和45.方向平均提高1.3和1.0,试验冷轧板的最高r值达到了3.23.     

武钢CSP低碳冷轧基料铁素体轧制工艺开发与实践

对CSP铁素体轧制、CSP奥氏体轧制和常规奥氏体轧制3种工艺生产SPHC钢卷的组织与性能进行了对比分析。结果表明,在相同化学成分下,CSP铁素体轧制钢卷屈服强度、抗拉强度和屈强比比奥氏体轧制钢卷均有较大幅降低,铁素体晶粒由10级降低为6~7级;CSP铁素体轧制钢卷与另2种工艺相比,可大幅降低冷轧机组的轧制力和轧制电流,减少轧机能耗,同时冷轧退火后性能更优良。     

宝钢1580热轧IF钢铁素体轧制工艺探讨

介绍了宝钢1580热轧铁素体轧制镀锡板用钢T-2.5CA的工艺参数制定及实际轧制效果。通过对其他IF钢实际轧制过程变形抗力与变形温度变化情况的分析,制定了合适T-2.5CA铁素体轧制温度制度和变形制度,并在实际轧制过程中取得良好效果,为在1580热轧进一步推广铁素体轧制提供了参考。     

ER70S-G含钛焊接用钢盘条双相区轧制问题分析

对含Ti焊接用钢ER70S-G盘条进行双相区轧制并采用较高的吐丝温度(≥780℃),后续通过斯太尔摩风冷线缓冷,盘条出现心部晶粒细化,但边部出现环状晶粒粗大现象。试验结果表明,对盘条金相组织为铁素体或铁素体+少量珠光体组织的低碳含Ti焊接用钢盘条进行双相区轧制,盘条边部晶粒易出现环状粗大情况,影响盘条的拉拔使用性能。     

铁素体区轧制技术及应用于攀钢生产的可行性

讨论了铁素体区轧制技术的优势,特点及其在国内外生产厂家的应用现状,分析限铁素体区轧制工艺在攀钢实施的可行性。     

在γ—α区轧制HSLA钢时轧制参数及其对强度和韧性的影响

本文研究了在奥氏体(γ)-铁素体(α)两相区的轧制条件下,HSLA(高强度低合金)钢板强度和韧性的匹配;分析了与轧制条件有关的钢板显微组织变化情况。揭示出变形铁素体的数量主要受轧制温度限制,并通过压下量研究{100}织构。铁素体结构受两个轧制参数的影响。从显微组织的角度看,轧制参数和合金元素的作用是使强度和韧性最佳匹配。通过研究,确定了钢板的工业性生产。同时指出,在奥氏体区进行压下以形成细奥氏体晶粒的两相区轧制,使碳当量低的钢板具有极好的强度和韧性匹配。     

铁素体轧制在传统热轧中宽带上的开发应用

阐述了唐山建龙利用传统中宽带生产线进行低碳钢铁素体轧制的过程,并对产品进行力学性能、金相和组织结构分析.结果表明,铁素体轧制组织为铁素体＋少量珠光体＋三次渗碳体,相对于奥氏体轧制,铁素体轧制屈服强度降低28％,抗拉降低13％,延伸率降低23％,冷轧屈服降低23％,抗拉降低12％,延伸率增加2％,n值增加7％,冷轧轧制力平均减小一半,r值降低25％,并对r值降低的原因进行了分析.经过客户多次实际应用,铁素体轧制实际应用效果良好.     

CSP线铁素体轧制与奥氏体轧制钢板的组织性能比较

利用光学显微镜、扫描电镜研究分析了CSP薄板坯连铸连轧线铁素体轧制工艺生产的钢板的显微组织,通过实验对其力学性能和成形性能进行了研究,并与该生产线采用常规奥氏体轧制工艺生产的钢板的组织性能进行了比较。研究结果表明：CSP线铁素体轧制工艺生产的钢板组织较粗大,强度较低,塑性较好,且具有良好的成形性。     

国内外铁素体轧制的研究和应用

超薄热轧带钢(<1.2mm)的铁素体轧制(低温轧制)能显著节约能源和降低生产成本。当前迅速发展的薄板坯连铸连轧技术为铁素体轧制的发展与应用创造了良好的条件。已采用铁素体温轧工艺的钢板为低碳钢薄板和微合金化钢薄板。总结了铁素体轧制时流动应力,再结晶,轧后产品组织和性能的研究现状和铁素体轧制的应用情况。     

热轧奥氏体不锈钢带钢酸洗工艺机理分析

 详细分析了热轧奥氏体不锈钢带钢的表面氧化皮形成机理、退火对氧化皮特性的影响机理、酸洗工艺机理。结论是：热轧奥氏体不锈钢带钢表面氧化皮外层主要以铁氧化物为主,内层主要以交替分布的Cr2O3和FeCr2O4层为主;退火后,氧化皮结构变得疏松多孔,且易脱落,贫铬层厚度增加,带钢更加容易酸洗;酸洗时,带钢表面的氧化皮主要通过机械剥离作用去除。分析结果对热轧奥氏体不锈钢带钢酸洗技术的改进具有一定的理论指导意义。     

Heredity Characteristic From Hot Rolled Microstructure to Annealed Microstructure in High Strength TRIP Steels

 The influence of hot-rolled process on microstructure in TRIP steel and the heredity characteristic from the hot-rolled microstructure to annealed microstructure are investigated. The results show there are two kind of hot-rolled microstructures under different coiling temperatures. One is composed of coarse grains of ferrite, pearlite and bainite, and the other is composed of small grains of ferrite, bainite and austenite. After annealing, the first kind of hot-rolled microstructure is greatly refined, and volume fraction, carbon content of austenite increase significantly. However, it have little changes in grain size, volume fraction and carbon content of austenite after the second kind of hot-rolled sheet is annealed. There are also differences in distribution of retained austenite between the two annealed microstructures observed by EBSD and TEM technology. Retained austenite in the first annealed microstructure distributes mainly inside of the polygonal ferrite in the form of spot, only little retained austenite on bainte ferrite boundary, however retained austenite in the second annealing microstructure allocates several places, such as inside of polygonal ferrite, on polygonal ferrite boundary, on bainte ferrite boundary.     

600MPa级热轧双相钢的组织性能

 介绍了实验室使用两段式冷却工艺试制的600MPa级热轧双相钢的化学成分及相变规律,利用光学显微镜、SEM以及拉伸试验对双相钢的微观组织和力学性能进行检测分析。结果表明：试验用钢的Ac1和Ac3分别为785、940℃;经830℃终轧后,空冷10s到750℃,在750℃开始快冷至卷取温度（≤200℃）,可得到室温组织为铁素体（86.5%）+马氏体的热轧双相钢,其屈服强度为327.1MPa,抗拉强度为651.6MPa,加工硬化率高达0.235,伸长率达25.7%。     

微合金化热轧TRIP钢的工艺模拟

 借助MMS-300热模拟试验机研究了控轧温度区间、终冷温度、贝氏体区等温处理以及冷却路径对微合金化热轧TRIP钢组织演变规律的影响。结果表明,随着控轧温度区间“下调”,组织中的铁素体晶粒越来越细小,铁素体量逐渐增加,残余奥氏体量则先增加后减少。终冷温度升高时,组织中的残余奥氏体量也呈现出先增加后减少的变化趋势,而贝氏体温度范围等温时间的延长使残余奥氏体量增加。相对于“缓冷+快冷”,轧后采用“快冷+缓冷+超快冷”冷却路径更有助于铁素体晶粒的细化和奥氏体的残留。在“快冷+缓冷+超快冷”冷却路径下,当控轧温度区间为900~840℃,缓冷温度范围为710~680℃,贝氏体等温处理制度为450℃×5min时,组织中的残余奥氏体量达到最高值113%。     

热轧钢板表面斑点缺陷分析

利用扫描电镜、光学显微镜等检测手段,对热轧钢板表面斑点缺陷进行了检验,分析了该缺陷的特征及产生原因。结果表明,热轧钢板表面斑点缺陷宏观特征为密集分布的近似圆形亮点,微观特征为异常粗大铁素体晶粒;层流冷却水不稳定过渡沸腾是导致斑点缺陷产生的主要原因;温度、板形等条件对斑点缺陷的产生均有较大影响。     

Effect of Cooling Method on Microstructure and Mechanical Properties of Hot-Rolled C-Si-Mn TRIP Steel

 The controlled cooling technology following hot rolling process is a vital factor that affects the final microstructure and mechanical properties of the hot-rolled transformation induced plasticity (TRIP) steels. In the present study, low alloy C-Si-Mn TRIP steel was successfully fabricated by hot rolling process with a 450 hot rolling mill. To maximize the volume fraction and stability of retained austenite of the steel, two different cooling methods (air-cooling and ultra-fast cooling “AC-UFC” and ultra-fast cooling, air-cooling and ultra-fast cooling “UFC-AC-UFC”) were conducted. The effects of the cooling method on the microstructure of hot-rolled TRIP steel were investigated via optical microscope, transmission electron microscope and conversion electron Mssbauer spectroscope. The mechanical properties of the steel were also evaluated by conventional tensile test. The results indicated that ferrite and bainite in the microstructure were refined with the cooling method of UFC-AC-UFC. The morphology of retained austenite was also changed from small islands distributing in bainite district (obtained with AC-UFC) to granular shape locating at the triple junction of the ferrite grain boundaries (obtained with UFC-AC-UFC). As a result, the TRIP steel with a content of retained austenite of 1152%, total elongation of 32% and product of tensile strength and total elongation of 27552 MPa·% was obtained.     

锌锅用热轧钢板解理断裂行为分析简

 通过断裂试样断口的宏观和显微分析、显微组织表征、拉伸和冲击试验以及解理断裂应力条件,讨论分析了锌锅用低强度级别钢板弯曲成形断裂的微观解理断裂行为。结果表明,钢板发生解理断裂的微观机制与冲击试样断裂相同,即晶粒尺寸控制的穿过晶界的裂纹扩展是解理断裂的临界事件。粗大的铁素体晶粒的面积分数过高显著降低了裂纹扩展阶段所需的局部解理断裂应力σf。断口宏观分析判断在钢板边部应存在导致应力集中的初始裂纹源,这极大降低了启动解理断裂的断裂应力并同时提高裂纹源前端的正应力σyy,扩大了解理断裂活跃区至初始裂纹前端,从而不可避免地发生脆性解理断裂。     

CSP热轧板卷边部裂纹成因及控制

为了抑制CSP热轧板卷边部裂纹,对CSP热轧板卷边部裂纹的成因进行了研究.CSP热轧板卷边部裂纹缺陷主要有3类:边部横裂纹、边部纵裂纹、边部烂边或掉块等.板卷产生边部裂纹的主要原因是:连铸坯表面边部横裂纹(包括深的振痕)和边部的细小纵裂纹,在加热和轧制过程中不断扩展;钢液在凝固以及铸坯在冷却、均热、轧制、层流冷却和卷取等过程中的热应力、机械应力以及相变应力等作用力超过钢的塑性变形抗力.抑制CSP热轧板卷产生边部裂纹的主要措施是:控制好合适的钢水成分;制定有效的工艺参数,如结晶器热流密度、结晶器振动参数、二冷冷却强度等.工业试验结果表明,CSP热轧板卷边部裂纹率由7.93%降低到1.81%.     

气雾冷却工艺对HRB400热轧带肋钢筋性能的影响

生产建材用HRB400热轧带肋钢筋过程中,由于钢坯合金元素含量接近内控标准下限而可能导致部分批号钢筋力学性能偏低甚至不满足国家标准要求,为寻求不增加合金元素含量的替代方法,以降低成本,进行了气雾冷却工艺生产HRB400热轧带肋钢筋组织与力学性能的试验研究。研究结果表明,在不增加合金元素含量的前提下,采用气雾冷却工艺,可细化钢筋表层组织晶粒,提高钢筋屈服强度10 MPa;可避免钢筋表面起泡现象的产生,有利于提高钢筋的表面质量。     

Effect of Alloying Element on Process Control of High Strength Hot-Rolled Dual Phase Steel

Microstructure evolution of C-Si-Mn-Nb,C-Si-Mn-Cr-Nb and C-Si-Mn-Cr-Mo-Nb tested steels during step-cooling process were studied.Effects of alloying element and process data on microstructure and mechanical properties of high strength Nb bearing DP steel were analyzed,to illustrate the relationship between alloy composition design and process control stability during DP microstructure and property control.It is shown that,700MPa ferrite and martensite DP steel is obtained respectively by three kinds of composition tested steel under different step-cooling process.C-Si-Mn-Nb steel with simple alloying design of low cost is provided with low hardenability,and has strong process sensibility during microstructure evolution.DP microstructure of ferrite and martensite of C-Si-Mn-Nb steel just can be obtained by coiling at low temperature of 250℃.The process control stability of C-Si-Mn-Cr-Nb steel is stronger than that of C-Si-Mn-Nb steel,to obtain DP microstructure by coiling at low temperature.C-Si-Mn-Cr-Mo-Nb steel with complex alloying design of high cost is provided with excellent process control stability.Alloy element Mo can promote stabilizing of metastable austenite to obtain F+M DP microstructure by coiling at medium temperature of 600℃.