超大型集装箱船用特厚止裂钢的发展

 超大型集装箱船用特厚止裂钢板由于优异的止裂韧性,能够显著减小复杂交变应力对甲板上部大开口部位形成的安全威胁。通过系统总结止裂韧性的评价体系、对比分析国内外超大型集装箱船舶的发展趋势和特厚止裂钢板的生产状况,综述了超大型集装箱船用特厚止裂钢板的显微组织特征和有可能实施的生产工艺。全厚度细小的等轴铁素体、多边形铁素体配合有限的细化贝氏体及心部γ线上的织构强化是改善特厚钢板止裂韧性的关键。东北大学提出的NEU-Rolling控轧工艺能够解决TMCP态特厚止裂钢板的生产难题。     

海洋平台用EH36厚钢板焊接接头的组织性能分析

按照EN 10225-2009附录E标准要求,采用50 kJ/cm大热输入埋弧焊工艺焊接厚为100 mm海洋平台用EH36钢板,测试分析了焊态及焊后热处理态焊接接头的组织与性能。结果表明,无论焊态还是焊后热处理态,EH36厚钢板焊接接头的硬度HV10≤280,抗拉强度≥510 MPa,-40℃冲击功均值≥50 J,表面组织以粗大的板条状贝氏体＋少量粒状贝氏体为主,心部组织以细小的铁素体＋珠光体为主,表明济钢开发的EH36厚钢板满足海洋平台的焊接生产要求。焊接接头表面与心部熔合线形状及传热状态的差异,是导致表面HAZ晶粒比心部粗大、因而表面韧性低于心部的主要原因。     

Nb、V、Ti微合金对压力容器用中厚板模拟焊后性能的影响

钢板的模拟焊后性能的摸索可以为钢板焊接过程提供可靠的数据,指导焊接工艺的制定,减少焊接对钢板母材基体和焊缝处的影响,以保证产品在使用过程中的性能和寿命,特别是压力容器用钢板,对使用过程中的性能安全和寿命要求严格。文中从成分设计、轧制、正火工艺等方面开展研究,找到最优的热处理工艺,保证钢板最佳的强韧性匹配。钢中添加铌、钒微合金元素,模拟焊后态的强度提高,尤其是屈服强度提高明显;并且板厚1/4处的低温冲击韧性和心部冲击韧性都明显改善。     

济钢50mm厚低碳TMCP型EH36船板的研制开发

根据EH36级船板的技术要求和3 500 mm中厚板生产线工艺装备特点,济钢通过合理的成分设计、优化的冶炼及轧制工艺,成功开发出低成本50 mm厚低碳TMCP型EH36级船板,并对研制钢板进行了相关的理化性能检验。结果表明:开发的EH36船板组织为均匀细小的针状铁素体+准多边形铁素体及少量的小颗粒珠光体,具有适当的强度和良好的低温韧性。     

高止裂韧度特厚板工业化生产技术开发及应用

随着集装箱船舶向超大型化发展，为保证船舶的安全航行，船体中部、顶部的舱口围顶板及上甲板边板等关键部位迫切需求最大100 mm厚度的高止裂韧性钢板。为此，基于NEU-Rolling轧制工艺开发出全厚度为均匀铁素体/贝氏体显微组织和止裂性能优异的100 mm规格EH47特厚止裂钢板。在低压缩比条件限制下，NEU-Rolling轧制工艺基于钢板“心-表”温差和负荷分配控制，通过提高厚向变形渗透性以细化心部奥氏体晶粒；通过反复相变耦合形变细化表层奥氏体晶粒，最终达到钢板全厚度奥氏体晶粒的细化、均匀化和近似相同的畸变状态，而细化、均匀的奥氏体晶粒是抑制钢板心部粗化贝氏体组织生成的关键。此外，钢板心部/近心部微观组织中{110}滑移面的含量相较于钢板表层提升而{001}解理面的含量下降，钢板心部韧性组织和有利织构因素所形成的优异的低温韧性，使心部和1/4厚度的显微组织在钢板全尺寸断裂时具有相近的阻滞脆性裂纹传播的能力，形成“多峰”分布的宏观断口。“多峰”分布的断口对脆性裂纹表现出明显的“钉扎”效果，减小裂纹尖端的应力扩大系数并提高了钢板全厚度断裂时的止裂韧性。宽板拉伸试验表明，开发的100 mm特...     

湘钢低焊接裂纹敏感性X610CF钢性能及工程应用

介绍了低焊接裂纹敏感性07MnCrMoVR钢(简称X610CF钢)的力学性能、组织结构及工程应用。该钢具有优异的焊接性能和低温韧性;板厚≤50 mm的钢板焊前不预热或稍加预热而不产生焊接冷裂纹,是制造大型压力容器(特别是低温和常温球罐)、水电站压力钢管的理想用材。     

湘钢低焊接裂纹敏感性X610CF钢性能及应用

介绍了低焊接裂纹敏感性07MnCrMoVR钢(简称X610CF钢)力学性能、组织结构及工程应用.该钢具有优异的焊接性能和低温韧性;板厚不大于50 mm的钢板焊前不预热或稍加预热而不产生焊接冷裂纹,是制造大型压力容器(特别是低温和常温球罐)、水电站压力钢管的理想用材.     

低焊接裂纹敏感性WDL系列钢的力学性能及组织结构

研究了低焊接裂纹敏感性０７ＭｎＣｒＭｏＶ系列钢的力学性能和组织结构。结果表明：该钢具有优异的焊接性能和低温韧性；板厚≤５０ｍｍ的钢板焊前不预热或稍加预热而不产生焊接冷裂纹，是制造大型压力容器、水电站压力钢管和水轮机蜗壳，高寒地区使用的大型工程机械、大跨度桥梁及海上采油平台等装备的理想用材。     

高强度船体结构用钢EH40生产实践

介绍了唐山中厚板材有限公司高强度船体结构用钢EH40的生产情况.采用铁水预处理、转炉自动炼钢、LF精炼、RH精炼、连铸重压下、电磁搅拌等国内先进技术,对钢水纯净度及连铸坯质量进行了有效控制.以低碳微合金化配合适当的控轧控冷工艺成功生产了高强度船体结构用钢EH40.钢板在-40℃下的横向和纵向夏比冲击功＞ 210 J.焊...     

高强度高韧性TMCP船板的研制

介绍了宝钢研制高强度高韧性TMCP(热机械控制轧制)40 kg级别系列船板的研究结果.结果表明,以低碳微合金化配合适当的控轧控冷TMCP工艺,试制厚度为68 mm 的高强度DH40、EH40、FH40船用钢板,钢板强度性能满足ABS、CCS、GL等九大船级社规范对DH40、EH40、FH40的要求,在-40℃、-60℃下,钢板横向、纵向具有大于200 J的夏比冲击功.同时焊接实验的结果表明,研制的钢板在焊接热输入量为50 kJ的条件下,焊接热影响区和熔合线具有良好的低温冲击韧性,能够满足船体结构用高强度高韧性钢板的要求.     

镁处理对CGHAZ冲击韧性及裂纹扩展的影响

通过镁处理Q345GJ钢引入含镁的复合夹杂物,研究其对大线能量焊接(线能量为100 kJ/cm)粗晶热影响区(CGHAZ)组织和断裂韧性的影响。结果显示,试验钢经镁处理后CGHAZ韧性值明显提高(冲击功由56 J提高到108 J)。主要原因为,镁处理钢在CGHAZ焊接热循环冷却过程中优先形成含镁的复合夹杂物,作为高表面能的惰性基体,其周围形成的贫锰区和高能应变场共同促进针状铁素体(AF)形核,AF体积分数为(82.9±2.0)%,宽度为(0.96±0.1)μm(无镁处理钢对应为(32.4±1.5)%、(3.13±0.2)μm);研究了大线能量焊接后CGHAZ冲击试样中微孔的形成及裂纹扩展,两种试验钢夹杂物附近均存在大量位错,变形过程中位错通过夹杂物时形成位错环堆积引起局部应力集中;当应力积累到无法使相邻晶粒的位错源开启时,不利于滑移取向上的应力达到临界值导致微孔的产生,相邻微孔在外力作用下连接形成裂纹。无镁处理钢CGHAZ区域微孔更为密集,受力后更易形成微裂纹。镁处理钢CGHAZ区域大角度晶界比例为80.2%、几何必要位错密度(GND)为0.806、局部取向差分布值(KAM)为0.91...     

低成本高焊接性能船板钢EH36的开发

工业化试制了3种厚度规格(20,26和36mm)的新型低成本高焊接性能船板钢EH36。试制钢板的显微组织由多边形铁素体和针状铁素体构成,其力学性能满足EH36级别船板要求并具有优异的低温韧性。采用焊接热模拟评价了钢板的焊接性能,当热输入由30kJ/cm升高至160kJ/cm时,粗晶区原奥氏体晶粒尺寸逐渐增大,其组织也逐渐由粒状贝氏体向晶界铁素体+晶内针状铁素体+晶内多边形铁素体转变,维氏硬度逐渐下降,低温韧性优异。得益于TiN粒子对奥氏体晶粒长大的抑制作用,微量B元素对先共析铁素体转变的抑制作用以及BN粒子对晶内铁素体形核的促进作用,焊接粗晶区获得了有利于韧性的细化组织,保证了粗晶区具有优异的低温韧性。双丝埋弧焊试验也验证了钢板具有优异的焊接性能。     

超低碳微合金X100管线钢CO2焊焊接接头的组织和性能

 采用CO2焊接方法焊接X100管线钢,分析了不同焊接工艺下焊接接头组织和性能的变化特征。随着焊接热输入的增加,焊接接头的屈服强度和抗拉强度降低,焊缝和热影响区处的冲击吸收功呈现先增大后减小的变化趋势,而焊缝组织均以针状铁素体（AF）为主。焊接热输入为1.17 kJ/mm时,粗晶区的显微组织主要是贝氏体铁素体（BF）,强韧匹配性最为优异;当热输入增加至1.91 kJ/mm时,粗晶区的组织除了BF外,还出现了粒状贝氏体（GB）,强韧水平明显降低。综合考虑,可将1.17 kJ/mm作为X100管线钢CO2焊接时的最佳热输入。     

Q690q耐候桥梁钢免预热焊接热影响区的组织性能

针对Q690q耐候桥梁钢,利用MMS-300热模拟试验机进行焊接热循环过程模拟试验,研究了10.5～114.9 kJ/cm热输入下粗晶热影响区(CGHAZ)、细晶热影响区(FGHAZ)和不完全相变热影响区(ICHAZ)的微观组织以及冲击韧性、硬度的变化情况,并观察了冲击断口形貌,然后采用优选的焊接热输入,进行了免预热的药芯焊丝熔化极气体保护焊(FCAW)和埋弧焊(SAW)的焊接工艺评定试验。结果表明,热输入较低时,CGHAZ和FGHAZ主要生成板条马氏体组织、ICHAZ出现岛状的M/A组元,其冲击韧性低、硬度高;热输入较高时,CGHAZ主要生成大尺寸的粒状贝氏体、准上贝氏体或上贝氏体组织,同时大尺寸的块状M/A组元数量不断增加、尺寸变大,其冲击韧性显著降低。FGHAZ生成较多多边形或准多边形铁素体、珠光体等高温转变组织,其硬度降低明显。ICHAZ除生成准多边形铁素体、无碳化物贝氏体和退化珠光体外,回火索氏体基体组织中的碳化物颗粒尺寸不断变大,其强韧性不断降低;热输入为18.2～25.7 kJ/cm时,CGHAZ以板条束细小且异向的板条贝氏体为主、FGHAZ形成细小均匀的板条贝氏体和粒状...     

Effects of Zr on acicular ferrite formation in HAZ of Ti-bearing low carbon steels with high heat input of weld thermal simulations

To research the effect of Zr addition on inhibiting austenite grain growth of Ti-bearing low carbon steels,two steels with different Zr contents were prepared using a laboratory vacuum induction furnace. The performance of HAZ under weld thermal simulations was investigated. The impact toughness,microstructure and the second-phase particle performance of HAZ under weld thermal simulations were investigated. The HAZ toughness was improved from 13 J to 87 J by addition of 0. 010 % Zr into the steel,with the fracture mechanism changing from cleavage fracture to toughness fracture,which was mainly attributed to the second-phase particles that were potent to nucleate acicular ferrite in HAZ during welding. It was concluded that the second-phase particles TiO x + MnS,ZrO 2 + MnS or TiO x + ZrO 2 + MnS were nucleated on ZrO 2 or TiO x ( x =1. 5,2) . This method can be applied to grain refinement by promoting the acicular ferrite formation and growth during large-scale welding,as in the cases of thick steel plates requiring higher heat inputs during welding.     

含Mg夹杂物对低合金高强度钢CGHAZ韧性的影响

摘要：采用Ca、Mg处理工艺研究不同夹杂物粒子对200kJ/cm大线能量焊接低合金高强度钢CGHAZ冲击韧性的影响,对各个试样CGHAZ的显微组织,晶粒尺寸和冲击功进行观察和分析。试验结果表明,在低合金高强度钢CGHAZ中,Mg处理钢的冲击性能明显高于Ca处理钢,主要原因是含Mg夹杂物粒子析出能力比含Ca夹杂物粒子强,在焊接过程中,含Mg夹杂物粒子对CGHAZ组织的钉扎作用更加显著;同时提高针状铁素体的含量,延长裂纹扩展路径,提高断裂时吸收的能量,使样品韧性得到提升。     

钒微合金钢粗晶热影响区的组织和韧性

 利用Gleeble-3800模拟焊接粗晶热影响区（CGHAZ）经历的热循环过程。比较了热输入100 kJ/cm条件下,V钢、V-N钢、V-Ti钢和V-N-Ti钢CGHAZ的组织和韧性,并分析了析出相情况。结果表明,CGHAZ的韧性从高到低依次为V-N-Ti钢、V-Ti钢、V-N钢和V钢;在V钢成分基础上添加钛可以有效细化原始奥氏体晶粒尺寸;V-Ti钢成分基础上增氮,一方面促进了（Ti,V）（C,N）/TiN的析出,抑制了原始奥氏体晶粒的粗化;另一方面促进了V（C,N）的析出,其促进了多边形铁素体的形成;多边形铁素体数量的增加能够减弱自由氮对韧性的破坏,同时有效改善了CGHAZ韧性。     

Investigation of the impact toughness of self-shielded flux-cored wire girth welds for X80 pipelines

Self-shielded flux-cored wire is a convenient and efficient consumable for pipeline field girth welding because of its self-protection characteristic and high deposition rate,especially for remote construction sites in rugged terrain. From the perspective of pipeline safety,the impact toughness of the girth welds is an important factor in pipeline integrity,which determines the crack arrest behavior in the girth welds. Therefore,improving the girth weld impact toughness is of primary importance in the field of pipeline girth welding. Three self-shielded flux-cored wires comprising different chemical composition systems have been applied to large diameter X80 UOE( U-ing-O-ingExpanding) pipeline semi-automatic girth welding,and the impact toughness of the welds has been evaluated by girth weld chemical composition analysis and microstructural analysis using scanning electron microscopy( SEM) and energy dispersive spectrometry( EDS) to investigate pipeline girth weld impact toughness and find ways to improve it.This helps in determining the main factors that influence girth weld impact toughness. Pipeline girth weld impact toughness is mainly determined by the final microstructure produced in the solid-state phase transition. In the as-weld state,acicular ferrite( AF) and fine bainite( FB) are a benefit to the impact toughness. For multilayer semiautomatic self-shielded flux-cored wire welding,the normalizing and tempering function of the latter beads to the initial beads plays an important role in the transition of girth weld microstructure,which affects the impact toughness. The original AF and FB and the corresponding heat treatment microstructure of the fine and uniform block ferrite and pearlite result in very good impact toughness. The following two mechanisms are found to promote the production of AF and FB in the girth weld. First,elements promoting the broadening of the austenitic region,such as Ni,C,Cu,and Mn,induce low temperature phase transitions and restrain the opposing function of Al,which is a benefit to the production of AF and FB. Second,dispersed high-melting-point inclusions,especially Al2O3,induce the nucleated production of AF. The advantageous function of inclusions is determined by their shape,distribution,and dimension. Dispersed spherical inclusions of small dimension are a benefit to the production of AF,and result in good impact toughness.     

The significant impact of Ti content on microstructure–toughness relationship in the simulated coarse-grained heated-affected zone of high-strength low-alloy steels

This study aims to investigate the influence of Ti addition on microstructure and toughness in the simulated coarse-grained heated-affected zone (CGHAZ) of high-strength low-alloy steels. The steels with low and high Ti content respectively were subjected to 100?kJ/cm heat input welding thermal cycle. The results indicated that the second-phase particles were mainly oxide covered with MnS and fine (Ti,Nb)N precipitate in low-Ti steel, which were modified to the oxide surrounded by TiN and coarse (Ti,Nb)N precipitate in high-Ti steel. Compared with low-Ti steels, the coarser precipitates induced larger austenite grain in CGHAZ of high-Ti steel. Moreover, the wrapping of TiN decreases the ability of inclusion to promote the nucleation of acicular ferrite, resulting in lower fraction of acicular ferrite in CGHAZ of high-Ti steel. Content of martensite-austenite constituent increased in CGHAZ of high-Ti steel. They were all responsible for the degeneration in toughness in CGHAZ of high-Ti steel.     

大线能量焊接用钢CGHAZ冲击韧性内在机理分析

针状铁素体(AF)一直被认为是提升大线能量焊接用钢粗晶热影响区(CGHAZ)韧性最有效的组织之一,但在一些试验中,有时即使发现CGHAZ中有大量AF组织,韧性也并不好。为了研究大线能量焊接用钢CGHAZ中不同类型组织及夹杂物对其冲击韧性的影响作用,从CGHAZ冲击试验出发,借鉴前人研究经验,对影响CGHAZ韧性的主要因素进行深入分析。结果显示,CGHAZ中微米级夹杂物容易成为裂纹萌生点,而晶内位错效应、冲击触发的体积效应等可以抑制裂纹传播,CGHAZ中析出的少量纳米级碳氮化物可以提升AF形核能力,增强CGHAZ韧性和强度,但当析出粒子过多时,会降低CGHAZ韧性。