控轧控冷工艺下普通C-Mn钢强化机理的研究

通过对2个普通C-Mn钢种控轧控冷实验,研究了控轧控冷工艺下普通C-Mn钢的强化机理.     

高强度低合金耐磨钢NM400的强韧化机制

采用控轧控冷工艺生产的高强度低合金耐磨钢NM400,具有高强度、高硬度和较高的韧性,其屈服强度为1 170MPa,抗拉强度为1 369MPa,平均硬度为403HB,伸长率为23%,-20℃冲击功为47J。光学显微镜观察发现,NM400的组织为回火马氏体,淬透性良好;透射电镜下观察发现,钢中存在大量纳米尺寸级析出物,能谱分析表明,析出物为Ti,Nb的碳氮化物。分析结果表明,耐磨钢NM400的强化机制主要为位错强化、细晶强化和析出强化;细晶强化是韧性提高的主要原因。     

1580mm热轧线Q345qE桥梁钢的试制开发

介绍了唐山不锈钢耐低温冲击桥梁钢Q345qE的开发过程。通过设计Nb-Ti复合强化成分体系,采用LF+RH双精炼、控轧控冷关键控制技术,成功开发出耐-40℃冲击桥梁钢。结果表明:8.0 mm热卷成品组织为F+P+B,强度满足标准要求,波动控制在±30 MPa,平均伸长率30%,-40℃平均冲击功270 J。     

钛微合金高强钢控轧控冷工艺研究

采用金相显微镜、电子显微镜等手段研究控轧控冷工艺对Ti微合金化高强钢的组织和性能的影响。结果表明:在低温终轧(800℃)、600℃保温1 h的试验钢的屈服强度和抗拉强度最高,分别为670.7 MPa和752 MPa。高温终轧(1 030℃)的试验钢组织主要为准多边形铁素体、针状铁素体和粒状贝氏体,组织粗大;低温终轧(800℃)的组织主要为多边形铁素体,晶粒较细小。在600℃保温1 h的试验钢中存在大量的纳米尺寸TiC粒子,沉淀强化效果明显,未在600℃保温1 h的试验钢中,TiC的析出受到限制,沉淀强化效果明显减弱。     

新型低成本细晶强化Q460级中厚钢板-UP460的研制

介绍了一种新型低成本Q460级中厚钢板-UP460的研制情况，其化学成分以传统16Mn钢为基础，不添加V元素，添加约0．02％的Nb元素，采用控轧控冷工艺(TMCP)主要依靠晶粒细化和析出强化提高钢材温度．试生产厚度规格为12-30mm的中厚钢板，力学性能满足GB／T1591-94要求．与传统Nb-V复合微合金化Q460级中厚板相比，合金元素用量大幅度降低，经济效益增加．     

鞍钢超低碳贝氏体钢HQ590DB热轧卷板生产实践

介绍了鞍钢HQ590DB超低碳贝氏体钢成分优化、钢质净化及微合金化过程，阐明了其在鞍钢1780热轧机组的控轧控冷工艺制度，包括温度制度及压下制度，尤其轧后加速冷却制度的优化过程，采用控轧控冷工艺实现了晶粒细化及沉淀强化，最终获得了极为细小的具有高密度亚结构的贝氏体组织。鞍钢1780机组首批试轧的超低碳贝氏体钢HQ590DB获得了优良的力学性能。     

控轧控冷工艺下微合金化钢强化机理的研究

通过控轧控冷工艺实验,分析了4种微合金化钢种的强化机理.     

DH36高强度船板钢综合强化机理

DH36船板钢是我国目前运用较为广泛的高强度船体结构用钢, 利用碳复型、XRD衍射、TEM观察分析等方法, 对控轧控冷后DH36钢中纳米析出物的类型、形貌、尺寸和数目等进行详细的讨论分析, 结果表明:DH36钢中的析出物组织形貌多为规则的方形, 其组成为（Ti, Nb）（C, N）; 试验DH36钢中析出的碳氮化物占基体的体积分数为0.00957 %, 总的析出强化贡献为211.24 MPa; 细晶强化为212.30 MPa; 固溶强化为122.93 MPa; 位错强化为134.43 MPa.      

低合金高强钢的强韧化机理与焊接性能

回顾了低合金高强度钢的发展历程,介绍了该类钢的强化机制、韧性机制以及焊接性能,并阐述了显微组织及合金元素对其性能的影响。采用微合金化成分设计与控轧控冷工艺相结合的方式,在传统强化方式基础上,在低合金高强钢中引入纳米沉淀相利用沉淀强化代替碳强化,使钢既保持了较高的强度和韧性,又提升了钢的焊接性能。     

控轧控冷HRB400钢筋位错强化效果定量研究

通过JEOL-2100扫描电镜观测控轧控冷HRB400钢筋和常规轧制的钢筋试样中位错的衍衬形态,建立位错密度测量模型,计算位错密度值;定量衡量控轧控冷HRB400钢筋中位错对强度的贡献,研究位错强化机理,揭示强度与位错密度的关系。结果表明,控轧控冷HRB400钢筋中位错强化作用明显优于常规轧制的钢筋。     

Development of TiMicroalloyed 600 MPa Hot Rolled High Strength Steel

 A high strength steel with tensile strength on the order of 710MPa had been development successfully with only addition of titanium alloy element based on a low carbon steel. The results show the hot deformation accelerates ferrite and pearlite transformation and retards bainite transformation under continuous cooling condition. The microstructure of this steel is mainly composed of fine-grained ferrite and carbides distributed along the ferrite grain boundaries. The yield and tensile strengths of steels are about 620～650MPa and 720～740MPa, respectively, and the values of strain hardening exponent (n) and plastic strain ratio (r) are 0.12 and 0.80, respectively, thus providing well-matched strength with toughness. In short, the fine-grained ferrite and TiC nano-precipitates play an effective role in strengthening the steel.     

热处理对高强度易切削沉淀硬化不锈钢2Cr16Ni3Mo2CuN力学性能的影响

高强度易切削沉淀硬化不锈钢2Cr16Ni3Mo2CuN在退火状态下有优良的切削性能。研究了经过一级退火温度710~800℃和二级退火温度570~620℃处理后2Cr16Ni3Mo2CuN钢的布氏硬度(HB)值,以及1 050~1 085℃45 min油冷,-70℃2 h,150,170℃回火后的力学性能。试验结果表明,710~740℃5 h空冷+620℃5 h空冷处理后,2Cr16Ni3Mo2CuN钢HB值在321以下;1 050~1 085℃淬火,150~200℃回火处理后,该钢强度极限σ_b≥1 520 MPa,δ₅≥12%,冲击功A_KU≥40 J。2Cr16Ni3Mo2CuN钢具有明显的二次硬化特征,二次硬化峰温度范围为480~520℃。     

控轧工艺对Mn-Mo-Nb-B系超低碳贝氏体钢力学性能的影响

以 6 2 0MPa、6 90MPa、780MPa三个级别的钢板生产为例 ,研究了Mn -Mo -Nb-B系超低碳贝氏体钢 (ULCB)钢坯加热、控制轧制、控制冷却、时效处理诸因素与钢的力学性能的关系。对三个强度级别的ULCB钢的合金成分与生产工艺提出了设计方案。研究表明 ,在适当的工艺制度下 ,在较低的碳当量基础上可以获得满意的强度与韧性。     

Strengthening Mechanism of a New 700 MPa Hot Rolled High Strength Steel

The microstructural evolution in a 700 MPa hot rolled high strength steel was analyzed in terms of strengthening mechanisms.The results show that the hot rolled sheet steel has yield strength of 710 MPa with good elongation and toughness.The strength of the developed 700 MPa hot rolled high strength steel is derived from the cumulative contribution of fine grain size,dislocation hardening and precipitation hardening.The fine grain strengthening and precipitation hardening are the dominant factors responsible for such high strength,and the amount of precipitation hardening is two or four times higher than that of conventional microalloyed hot rolled sheet steels reported in the past.Good toughness is due to refinement of ferrite grain size.     

高延伸膨胀管用钢的力学性能及微观组织

 采用低碳低合金的成分设计开发了一种新型的膨胀管用钢。经优化的（α+γ）两相区退火工艺处理后,钢材呈现出强度高、延伸性能好、加工硬化能力强、冲击韧性以及高温力学性能优良等特点。常温条件下,该膨胀管材料的抗拉强度超过了700MPa,伸长率超过了40%,强塑积达到了30GPa·%,半厚冲击韧性超过了50J;300℃高温条件下,该类钢仍具有620MPa以上的抗拉强度,40%以上的伸长率以及25GPa·%以上的强塑积。采用SEM和XRD对材料的微观组织进行了表征,该类钢具有马氏体+残余奥氏体+铁素体的多相组织结构形貌。由于弥散分布的小尺寸残余奥氏体在形变过程中的TRIP效应,使得该类钢种在拉伸过程中获得了持续加工硬化的能力,从而获得了强度与塑性的优良结合。     

热处理对Φ245 mmx l2 mm V150高抗挤毁套管用钢27CrMnMoV组织和性能的影响

试验用Φ360 mm 27CrMnMoV钢(/%:0.27C,0.25Si,0.92Mn,1.06Cr,0.75Mo,0.009P,0.003S,0.088V)铸坯经穿孔和Φ340连轧机组热轧成Φ244.48 mm×15.11 mm无缝管。试验研究了830～950℃水淬,880℃水淬+600～680℃ 30～120 min回火,以及880℃两次水淬+620～660℃回火工艺对该钢管组织和性能的影响。一般要求V150管屈服和抗拉强度分别为1034～1241 MPa和≥1103 MPa,0℃横向冲击功≥80 J。结果表明,一次淬火+630～655℃ 60min回火时Mo和V碳化物析出产生二次硬化,其屈服和抗拉强度分别为1 034～1 150 MPa和1 103～1 225 MPa,0℃横向冲击功为80～108 J。二次淬火+635～655℃ 60 min回火工艺,循环淬火使奥氏体晶粒细化,提高强度的同时显著改善韧性,其屈服和抗拉强度分别为1 034～1 170 MPa和1 103～1 240MPa,0℃横向冲击功为80～120 J,比一次淬火+回火工艺更容易实现V150高抗挤毁套管性能的稳定性控制。     

轧制与冷却工艺对X65薄规格管线钢组织与性能的影响

系统研究了控轧及控轧控冷工艺对9.5mm薄规格X65管线钢组织和性能的影响。结果表明:控轧控冷生产的钢的强度、韧性及微观组织整体优于控轧型X65管线钢。对于控轧工艺,降低轧制温度,晶粒细化,强度提高至550MPa,屈强比有增大趋势(0.90～0.95),但韧性较差;轧后配合水冷,通过优化冷却温度和精轧开轧厚度,组织明显细化,混晶程度和带状组织均改善,强度提高至580～620MPa,-20℃冲击韧性稳定在130～150J,屈强比稳定在0.83～0.9。无论是控轧工艺还是控轧控冷工艺,仅通过降低轧制温度、冷却温度对钢的强度提高幅度有限。     

Effect of Heat Treatment Process on Properties of 1000 MPa Ultra-High Strength Steel

 Two types of steel, C-Mn-Cr-Mo-B microalloyed steel and C-Mn-Mo-Nb-Cu-B microalloyed steel, are designed to develop 1000 MPa ultra-high strength steel. Two kinds of processes, thermomechanical controlled process (TMCP) combined with traditional off-line quenching and tempering (QT) process versus controlled rolling process (CR) combined with direct quenching and tempering (DQ+T) process, are applied. The effect of heat treatment processing mode on the microstructure and mechanical properties is studied. The relationship between microstructure and mechanical properties is investigated by SEM and TEM. After tempering at 450 to 550 ℃ for 1 h, the steel produced by TMCP+QT process shows combination of excellent strength and low temperature toughness. The yield strength is above 1000 MPa, elongation above 15% and impact energy at -40 ℃ more than 30 J. After tempering at 450 ℃, a large number of ε-Cu particles precipitated in C-Mn-Mo-Nb-Cu-B steel produced by CR+DQ+T process lead to a significant increase in yield strength. And after tempering at 500 to 600 ℃, the yield strength of the steel is further improved to 1030 MPa because of precipitates, such as nitride or carbide of niobium, carbide of molybedenum and vanadium. When the tempering temperature is increased above 620 ℃, the yield strength is still higher than 1000 MPa and elongation is above 20% and impact energy at -40 ℃ is more than 35 J. After tempering at above 500 ℃, the toughness of the steel treated by TMCP+QT process is superior to that of steel by CR+DQ+T process.     

磷钛微合金化超低碳高强钢的时效强化及力学性能

研究了含微量磷，钛高强钢的时效强化及力学性能，结果表明实验钢具有明显的时效强化效果，时效强化和加工硬化的综合作用可使钢材获得1200MPa的强度和高于10％的伸长率，还可以借助加工工艺参数控制钢材强度和塑性的配合，讨论了这各新型微合金高强度钢的特点，组织与性能变化的规律。