宝钢1880mm热轧试生产DP600双相钢的组织性能

采用Si-Mn系简单成分设计,充分发挥宝钢1 880 mm热连轧机组的密集冷却能力和卷取能力,通过密集水冷—空冷—水冷的三段式冷却模式和低温卷取,成功实现在1 880 mm机组工业试生产600 MPa级热轧双相钢。结果表明,通过合理的冷却速度、中间待温温度和待温时间配合,试验钢可获得铁素体和马氏体比例适合的双相组织,力学性能满足600 MPa级双相钢设计要求;同时试验发现,冷却和卷取工艺显著影响双相钢的微观组织和性能,因轧速变化造成钢卷头尾冷却条件不一致,导致钢卷不同位置力学性能波动较大。     

CSP流程生产经济型热轧双相钢的工艺与组织性能

 为了在CSP产线上开发新一代经济型热轧双相钢,并确定生产的最佳成分和工艺,介绍了在武钢CSP生产线进行580MPa级热轧双相钢的工业化生产试制情况。分别采用C-Mn-Si系和C-Mn-Si-Cr系钢为原料,通过控制轧制和基于超强冷却设备的控制冷却工艺,成功开发出抗拉强度580MPa级热轧双相钢。通过比较分析2种成分钢的力学性能和微观组织,结果表明：经济型的C-Mn-Si系钢相对于C-Mn-Si-Cr系钢具有屈服强度低、屈强比小、伸长率大的特点,虽然马氏体量相对较少,但具有马氏体呈岛状更加均匀分布在铁素体晶界上等典型双相钢的特征,同时提出了生产过程中控制铁素体析出量和促进马氏体形成的具体措施。     

冷却工艺对Si-Mn系热轧双相钢组织和性能的影响

通过热轧试验研究了3种冷却工艺对传统成分Si-Mn系热轧双相钢组织及性能的影响。试验结果表明：在3种冷却工艺条件下,试验钢的最终组织为铁素体和马氏体双相组织。当终轧后采用空冷＋超快冷的冷却工艺时,钢板的屈强比最低,伸长率和n值最大,晶粒尺寸较大,但强度相对最小;当终轧后采用层流冷却＋空冷＋超快冷的冷却工艺时,钢板的晶粒...     

低成本C-Si-Mn双相钢DP600开发试验研究

在某1780生产线上,采用C-Si-Mn简单成分体系低成本策略,采用控轧控冷工艺,使600MPa级热轧双相钢在工业试生产中取得一定突破,本文具体阐述了化学成分及工艺条件对双相钢微观组织及性能影响。     

双相型热轧汽车结构钢的试制

通过实验室轧制和卷取模拟试验,研究热轧双相钢工艺与组织性能关系。结果表明:采用C-S i-Mn-Cr系成分和轧后两段式冷却,在低温卷取工艺下,可获得理想的铁素体+马氏体双相组织,且力学性能优异;由组织性能分析可知,本试验钢的铁素体体积分数主要取决于开冷温度,而两段水冷间的空冷时间影响不明显;同时,由回火试验分析可知,试验钢在175℃以下时,马氏体处于稳定状态。     

包钢CSP生产线生产540 MPa级热轧双相钢

介绍了在包钢CSP生产线研制540 MPa级热轧双相钢的工业化生产试验.采用C-Mn钢为原料,分别利用原层流冷却能力和超快冷设备,通过控制轧制和控制冷却工艺,成功开发出540 MPa级热轧双相钢160 t.试制的钢带具有屈服强度低、屈强比小、伸长率大、n值高及低温冲击韧性良好等特点,并具有拉伸曲线无屈服平台、马氏体呈岛状均匀分布在铁素体晶界上等典型双相钢的特征.经汽车制造厂试用,制成了汽车横梁和重型翻斗车护板等构件.     

超快冷方式下热轧双相钢的生产工艺

研究了超快冷方式下热轧双相钢的生产工艺,采用分段冷却方式,介绍了空冷温度、空冷保温时间、卷取温度、过钢速度等工艺参数的制定原则,结合相变理论,采用模拟计算方法,得到各个参数的参考值范围。该工艺应用于热轧现场获得良好性能的双相钢,其抗拉强度达到700MPa。     

超快冷方式下热轧双相钢的生产工艺

 研究了超快冷方式下热轧双相钢的生产工艺,采用分段冷却方式,介绍了空冷温度、空冷保温时间、卷取温度、过钢速度等工艺参数的制定原则,结合相变理论,采用模拟计算方法,得到各个参数的参考值范围。该工艺应用于热轧现场获得良好性能的双相钢,其抗拉强度达到700MPa。     

700 MPa级热轧双相钢的组织和性能

 采用热模拟并借助光学显微镜、SEM技术研究了双相钢的相变规律及不同工艺参数下的组织演变规律。根据热模拟结果在实验室试制出700 MPa级热轧双相钢,优化了轧制和冷却工艺参数。实验结果表明：热轧双相钢组织为多边形铁素体+马氏体岛,抗拉强度730 MPa,屈强比062,伸长率236%,达到了DP700级双相钢的性能要求,并讨论了热轧卷取温度对双相钢最终力学性能的影响。     

热轧冷却工艺对Nb-Ti微合金双相钢组织和性能的影响

研究了热轧后空冷(800-850℃→750℃)+水冷(750℃→300～180℃)的两段式和水冷(782℃→760℃)+空冷(760℃→713℃)+水冷(713℃→414℃)三段式冷却方式对双相钢(％:0.08C、1.02Mn、0.22Si、0.02Nb、0.01Ti)组织和机械性能的影响。结果表明,采用两段式冷却方式可得到铁素体+分散的板条马氏体组织,并使铁素体尺寸达5.5μm,钢的屈服强度为345～365 MPa,抗拉强度为565～575 MPa、屈强比为0.60～0.65,优于三段式冷却方式轧制的双相钢。     

Effects of Processing Variables on Microstructure and Yield Ratio of High Strength Constructional Steels

The process of “controlled rolling+relaxation+ultra fast cooling (UFC)”for high strength constructional steel with low yield ratio was presented.Microstructure and corresponding relationship with low yield ratio were in-vestigated.The results showed that the constructional steels with multiphase microstructure of bainitic ferrite,mar-tensite-austenite (M-A)and lath bainite were obtained through the creative process.The grain size decreased with the decrease in finish rolling temperature,which enhanced the strength by the grain refinement strengthening.The proper relaxation treatment promoted the bainitic ferrite lath width and the formation of blocky M-A constituent.In addition,both the tensile and yield strength increased with the decrease in finish rolling temperature and UFC final temperature,but the yield strength increased more significantly than tensile strength,which caused the increase in yield ratio.By using the process of “controlled rolling+relaxation+ultra fast cooling”,the excellent comprehensive mechanical properties of 780 MPa grade constructional steels of 12-40 mm in thickness were achieved.     

冷轧退火板DP钢成材率低原因分析

摘要：以冷轧退火板DP980为研究对象,结合生产过程中的工艺过程参数,利用金相显微镜、电子显微镜、显微硬度计、室温拉伸试验机对热轧卷、冷硬卷、退火卷试样的显微组织、硬度、强度、伸长率等进行了分析。结果表明,热轧卷生产过程中,为了控制带尾抛钢稳定性而降低卷取速度,导致带尾卷取温度较低,力学性能不均,遗传到冷轧工序转变为厚度波动。目前,冷轧各工序通过切头尾的方法,对于此问题进行控制,也就导致了DP钢成材率较低。     

Effects of Finish Rolling Temperature on Microstructure and Mechanical Properties of Ferritic-Rolled P-Added High Strength Interstitial-Free Steel Sheets

  The steels were rolled at 3 different finishing temperatures. The mechanical properties were tested by tensile tests. The results show that as finish rolling temperature decreases from 620 to 560 ℃ in ferrite region, the deep drawability of ferritic rolled P added high strength IF steels is improved, and r value rises from 114 to 137. Finish rolling temperature (FT) has less influence on other mechanical properties, such as yield strength, tensile strength and elongation. Microstructures of hot rolled and annealed steel sheets and precipitates of annealed steel sheets were also analyzed.     

Nb对C Si Mn Cr双相钢相变规律、组织和性能的影响

  根据C Si Mn Cr和C Si Mn Cr Nb实验钢的相变规律,在实验室进行了控轧控冷实验研究,分析了微合金元素Nb对高强度热轧双相钢相变规律、组织和性能的影响。实验结果表明,Nb可显著推迟铁素体和珠光体转变,并显著降低铁素体开始转变温度,但对铁素体终止转变温度和贝氏体转变温度区间基本没有影响。经Nb微合金化后,实验钢的屈服强度和抗拉强度增幅均在100 MPa以上,屈服强度的增幅高于抗拉强度,且在强度大幅度升高的同时,伸长率下降并不明显,表明Nb的细晶强化作用对提高中温卷取热轧双相钢强度级别的效果明显。     

Heat Treatment of Cold-Rolled Low-Carbon Si-Mn Dual Phase Steels

 The effects of over aging (OA) and vanadium on microstructure and properties of cold-rolled low-carbon Si-Mn vanadium-bearing and traditional dual-phase steel sheets are studied. The results show that the microstructure and mechanical properties of DP steels are greatly affected by over-ageing temperature. When OA below 250℃, the elongation rate increases sharply whiles both the yield strength and tensile strength decrease slightly, this is favorable to the increase of all over mechanical properties. After OA above 300℃, elongation does not increase much, but the yield strength increases and tensile strength decreases, which deteriorate the mechanical properties of the steel. Finally, the results also show that both the hardenability and the tempering stability of steel can be significantly improved by vanadium micro-alloying.     

Improvement of Mechanical Properties of Reinforcing Steel Used in the Reinforced Concrete Structures

SAE1010 structural carbon steel, which has a low cost price and wide range of use in the construction industry, has been studied as dual phase (DP) steel subjected to appropriate heat treatment, and its mechanical properties have been investigated under various tempering conditions. Intercritical annealing heat treatment has been applied to the reinforcing steel in order to obtain DP steels with different martensite volume fraction. In addition, these DP steels have been tempered at 200, 300 and 400 °C for 45 min and then cooled to the room temperature. Mechanical properties such as tensile strength, yield strength, reduction in cross-sectional area, total elongation, resilience modulus and toughness have been examined. Furthermore, fractographic examination has been done with scanning electron microscope (SEM) as well as metallographic examination of the steels. As a result of this study, it is found that mechanical properties of DP steel have changed according to the hardness and ratio of martensite phase. In addition, tensile strength, yield strength and resilience modulus of the steels have been reduced. In contrast, the total elongation, reduction of the cross-sectional area and toughness have been increased.     

控轧控冷工艺对SCM435钢盘条组织和性能的影响

试验钢SCM435（/%:0.33~0.38C,0.15~0.35Si,0.60~0.85Mn,≤0.025P,≤0.025S,0.90~1.20Cr,0.15~0.30Mo）盘条的生产流程为80t BOF-LF-280 mm×325 mm铸坯-160 mm×160 mm热轧坯-热连轧成Φ16 mm盘条。试验研究了160 mm×160 mm热轧坯由常规轧制工艺（开轧1060℃,精轧930~950℃,吐丝860~900℃,冷却速度0.5~0.6℃/s）和控轧控冷工艺（开轧1060℃,精轧820~850℃,吐丝780~820℃,冷却速度0.4~0.5℃/s）对SCM435钢热轧盘条组织和力学性能的影响。结果表明,随着精轧温度的降低和冷却速度的减小,钢热轧盘条的组织得到改善,抗拉强度明显降低;常规工艺轧制SCM435钢热轧盘条的抗拉强度平均952 MPa,组织为铁素体+珠光体+贝氏体+马氏体,控轧控冷工艺轧制的SCM435钢热轧盘条的抗拉强度平均817 MPa,组织为均匀的铁素体+珠光体。结合控轧控冷工艺原理对钢的组织和性能变化进行了分析。