超厚板DH40船用钢焊接热影响区韧性研究

采用SAW焊接方法,使用多层多道焊接技术对超厚板DH40船用钢进行了焊接性试验,重点探讨了热影响区微观组织与接头冲击性能之间的内在联系.结果表明,熔合线外5mm区域的冲击性能较其它部位低的原因在于多层多道焊最后一次焊接热循环作用下,由于“组织遗传”作用,出现晶粒粗大造成的;焊缝根部熔合线外5mm区域冲击性能严重衰减是由于该区域出现了大量粒状贝氏体.改善焊接工艺或进行焊后热处理,使M-A组元分解成铁素体和碳化物是提高其韧性的有效方法.     

F550Z高强钢埋弧焊焊接工艺及接头性能研究

采用CHW-SEM2NP型焊丝和CHF606氟碱型烧结焊剂,用埋弧焊焊接F550Z钢,研究了不同的热输入对F550Z钢焊接接头抗拉强度和-60℃冲击韧性的影响。结果表明:随着热输入的增大,接头抗拉强度没有出现明显的变化,接头强度对热输入不敏感;焊缝中心的冲击韧性随着热输入增加,呈现先降低后升高的趋势,熔合线及熔合外2 mm处冲击韧性随热输入增加而减小,当热输入超过27 k J/cm时,熔合线及熔合线外2 mm处冲击韧性已经达不到使用要求;焊接接头的硬度分布均匀,焊缝中心较母材处略低,没有出现较大的波动。埋弧焊焊接F550Z钢时,焊接热输入不超过27 k J/cm时,可以得到较好性能的焊接接头。     

大间隙FAB埋弧焊焊接试验及接头性能

对两种相同成分、不同厚度的DH36船用钢板进行大间隙不同填充材料的FAB埋弧焊接试验,分析焊接接头力学性能和微观组织特点。结果表明:采用FAB埋弧焊打底及埋弧焊填充盖面的工艺焊接后的接头抗拉强度、弯曲性能、硬度值、冲击韧性等性能指标都能满足规范要求;焊缝中心是整个接头冲击韧性最薄弱位置,表面焊缝中心采用多层多道焊接,其冲击值高于根部;填充材料碎焊丝和铁粉成分不同,但对于根部焊缝中心冲击值的影响不大;母材采用TMCP工艺制造及低碳成分设计,热影响区组织粗化不明显,冲击韧性良好。     

船用管-管机器人焊接接头组织和性能

采用机器人焊接系统进行了船用管-管MAG对接焊,分析了管焊接接头的力学性能和微观组织.结果表明:侧弯试验的试样焊缝和熔合区均无裂纹,焊接接头的抗拉强度高于母材,焊缝金属的硬度均高于其两侧的热影响区和母材,且其冲击吸收功明显高于热影响区,在熔合线外2mm和5mm处,热影响区的冲击吸收功明显较低.由于采用多层多道焊,后层焊道对前层焊道的重复加热类似于"正火",使得焊缝层间柱状晶组织被打乱,获得细小的铁素体+少量珠光体组织,对焊缝金属的性能起到了很好的改善作用:而热影响区粗晶区粗大的魏氏组织和不完全重结晶区存在的大块铁素体,导致韧性明显降低.     

40mm高强钢窄间隙激光填丝焊接头组织与性能

采用窄间隙光纤激光填丝多道焊的方法焊接了40 mm厚Q345D船用钢板,利用光学显微镜、扫描电镜和拉伸试验机分析了接头组织与性能。结果表明,选取合适的窄间隙激光填丝焊工艺可以得到成型好、无气孔和未熔合等缺陷的焊接接头,焊缝由13层构成,每层堆高约3 mm,焊缝宽度约为3.5 mm。填丝焊缝组织主要为铁素体和粒状贝氏体,焊缝中心冲击韧性良好。热影响区主要为马氏体组织,填丝焊的最高硬度值均出现在焊接热影响区,随着热输入的增加,热影响区最高硬度增加。拉伸试样均断于母材,焊接接头具有良好的力学性能。     

焊接工艺参数对Q690D高强钢多层多道焊缝缺欠的影响

针对液压支架结构件用Q690D高强钢多层多道焊焊缝,通过焊缝横截面形貌分析、X射线检测等分析手段研究了焊接电流、保护气体流量、焊丝干伸长、坡口拼装间隙等焊接工艺参数对焊缝缺欠类型、位置与数量的影响,并通过拉伸试验、冲击试验测试了焊接接头性能。结果表明,液压支架结构件用Q690D高强钢多层多道焊焊缝中缺欠以气孔、未熔透和未熔合为主,其中气孔约占43%,未熔透约占30%,未熔合约占23%;缺欠主要集中于焊道根部、焊缝内、焊道与母材熔合线处、焊道之间等位置,其中,焊道根部缺欠数量约占54%,为焊缝缺欠最集中的位置;试验范围内,焊接电流、保护气流量、焊丝干伸长等参数对焊缝内部缺欠影响较大,而对焊缝根部缺欠无明显影响;拼接间隙对焊缝根部未熔透、气孔等缺欠有明显的影响作用,当拼接间隙为2mm时,可有效减少根部缺欠;保护气种类主要影响焊缝成形质量,而对焊缝缺欠无明显影响;优化工艺参数后,焊缝缺欠明显降低,无明显未熔透、未熔合等缺欠,气孔率约2.1%,接头抗拉强度达798.6MPa,接头性能良好。     

厚板Invar钢多层多道焊与多层摆动焊效率与接头质量对比分析

对19 mm厚Invar钢板进行多层多道焊和多层摆动焊对接试验,计算分析了这两种工艺的功耗和效率,并通过观察和测量Invar钢焊件的金相组织和显微硬度以比较两种焊接方法的焊接接头质量。结果表明,在连接厚板Invar钢时,由于多层摆动焊焊道数少于多层多道焊焊道数,多层摆动焊所用焊接时间较少、效率更高、功耗更少;多层摆动焊的层间重熔区熔合良好,而多层多道焊接接头处观察到明显的未熔合缺陷;多层摆动焊的热影响区宽度远小于多层多道焊;多层摆动焊的平均晶粒尺寸及显微硬度均略大于多层多道焊。     

船用高强钢双丝窄间隙GMAW组织与性能研究

采用自行研制的双丝窄间隙熔化极气体保护焊(GMAW)焊接系统,对32 mm厚船用高强钢厚板进行了多层单道窄间隙GMA焊接,对其焊接接头进行了组织分析和性能测试.试验结果表明:在适宜的焊接参数下,双丝窄间隙GMAW能够获得无侧壁未熔合及其它宏观缺陷成形良好的焊缝;接头热影响区小,抗拉强度高,无软化及脆化现象,冲击韧性和硬度分布均满足使用要求.     

D36海洋平台用钢Plasma-MIG复合电弧焊接工艺研究

D36海洋平台用钢是造船和海洋平台行业不可或缺的材料,本研究采用Plasma-MIG复合电弧焊接实现了厚25 mm的D36钢对接实验。实验表明:采用优化的12道规划路径的Plasma-MIG多层多道焊焊接工艺参数可以满足焊缝宏观形貌要求,焊缝成形美观,无气孔、夹杂、未熔合等缺陷。与传统MIG焊D36钢接头抗拉强度相比,Plasma-MIG复合焊工艺能够提高D36钢的焊接接头强度。Plasma-MIG复合电弧焊接厚25 mm的D36钢焊缝底部的冲击功为62.26 J,中部为103.27 J,顶部为124.68 J,均远大于海洋工程平台建造焊接规范标准的34 J。因此,焊缝具有较好的低温冲击韧性。     

特厚板埋弧焊工艺研究

从焊材选择、焊接电源和焊丝排列等方面介绍了特厚板埋弧焊的工艺特点,并且采用正面双丝埋弧焊和反面三丝埋弧焊的焊接方法对150 mm厚的低合金钢Q345D厚板进行了对接平焊,对比分析了两种焊接工艺下焊接接头的力学性能和微观组织。结果表明,采用合理的电源组合、焊丝排列和合适的焊接材料,所得焊缝内部无夹渣、气孔等焊接缺陷,焊缝成形美观;焊接接头抗拉强度均高于母材,所有弯曲试样均合格,焊接接头整体冲击韧性满足了标准要求,但在多层多道焊的条件下,距离熔合线5 mm区域出现了韧性下降的现象,原因是多层多道焊接热循环影响下造成该区域晶粒粗大,同时出现了大量粒状贝氏体。     

Evaluation of cryogenic fracture toughness in SMA-welded 9% Ni steels through modified CTOD test

As the first step of the study for the safety performance of LNG storage tank based on the concept of fitness-for-purpose, the change of cryogenic toughness within the X-grooved weld HAZ (heat-affected zone) of SMA (shielded metal arc)-welded QLT (quenching, lamellarizing, and tempering)-processed 9% Ni steels, was investigated qualitatively and quantitatively. In general, CTOD (crack tip opening displacement) test is widely used to determine the fracture toughness of steel weldments. But there is no standard or draft for evaluating the toughness of thick weldment with X-groove such as in this case. Therefore, in this study, modified CTOD testing method for fatigue precracking. calculation of CTOD, examination of fractured specimen was proposed and used. And the results of modified test were compared with those of conventional CTOD test and Charpy V-notch impact test. In addition, the relationship between the fracture toughness and microstructure was analyzed by OM, SEM and XRD. The cryogenic toughness in HAZ decreased as the evaluated region approached the fusion line from base metal. The decrease in toughness was apparently caused by the reduction of the retained austenite content and the absence of grain refinement effect in the coarse-grained zone in HAZ. The austenite reduction resulted from the decrease in nucleation sites for α’γ reverse transformation due to the increase in fraction of coarse-grained zone within HAZ. More complex thermal cycles in the mixed zone of weld metal and base metal caused the poor stability of retained austenite in the zone by the redistribution of alloying element in retained austenite. Due to this reason, the toughness drop with decreasing test temperature in F.L. (fusion line)-F.L.+3 mm was larger than that in F.L.+5 mm and F.L.+7 mm.     

Laser-TIG hybrid welding of ultra-fine grained steel

For improving the weldability of ultra-fine grained (UFG) steel, detailed experiments of laser-tungsten inert gas (TIG) hybrid welding were carried out on this material to investigate the effects of welding parameters on weld shape, microstructure, grain growth in heat-affected zone (HAZ) and mechanical performance. For the hybrid welds, increasing energy ratio of laser to arc (ER_LA) can narrow weld width, reduce the tendency of grain growth and ferrite grain coarsening in HAZ and also make the microstructure of fusion zone gradually change from coarse pearlite to fine martensite and bainite. The hybrid weld with low ER_LA has obvious softening zone in HAZ; while that with high ER_LA has no softening zone because of the low line energy. Compared to laser weld, under appropriate welding parameters hybrid weld with high ER_LA can obtain higher welding speed, better weld shape and more sound mechanical performance including similar tensile strength and higher toughness. These results demonstrated that laser-TIG hybrid welding is an effective process for UFG steel.     

大热输入焊接EH36船板钢接头力学性能

以EH36高强度船板钢为研究对象,通过拉伸和冲击分析试验手段,对EH36船板钢不同热输入埋弧焊接头进行了力学性能测试,同时采用扫描电镜对冲击试样断口形貌进行分析.结果表明,所有断裂均发生在拉伸试样的母材区,EH36船板钢在大焊接热输入条件下,焊缝和焊接热影响区的强度好于母材,并没有出现热影响区软化现象;随着焊接热输入增加焊缝的冲击韧性降低,从焊缝和熔合区断口形貌来看,断裂类型为韧性断裂和准解理断裂的混合断裂.随着远离熔合线距离的增加,冲击吸收功有增加的趋势,在距离熔合线4 mm处的冲击吸收功跟母材接近,说明该位置处韧性基本不受焊接热循环的影响.     

铸造Ti-Al-Mo-Zr钛合金电子束焊接接头组织与性能

选用电子束焊接方式对14 mm厚铸态Ti-Al-Mo-Zr钛合金进行焊接,在合适的工艺参数下获得成形良好、无内部缺陷的焊接接头。室温下测试与分析焊接接头的显微组织、显微硬度和力学性能,结果显示焊缝处主要由β相基体和粗大的针状α相组成,热影响区处受焊接热循环作用部分转变为网状片层组织。焊缝处硬度略高于母材处,接头整体硬度分布均匀,无明显弱化区域;接头焊缝处抗拉强度优于母材,焊缝处冲击值AKV达到75 J/cm~2,热影响区冲击值为73 J/cm~2,Ti-Al-Mo-Zr钛合金电子束焊接接头冲击韧性良好。     

高铌X80管道不同强度匹配环焊接头性能及应变演化

为探究管道环焊缝断裂失效机理,测试了两种不同强度匹配的高铌X80环焊缝接头的组织和性能,并借助数字图像相关法(digital image correlation,DIC)观测了焊接接头在拉伸载荷下的应变行为.结果表明,低强匹配和高强匹配的高铌X80管道环焊接头均具有较好的冲击韧性,二者的夏比冲击吸收能量平均值相当,热影...     

Cr5Mo钢管及其焊接接头长期服役后的组织性能与剩余寿命

本文研究了炼油厂铂重整装置临氢系统Cr5Mo耐热钢管及其焊接接头长期服役后的显微组织、力学性能和剩余寿命。试验结果表明,母材的组织和性能变化较小,估计还可继续使用10万小时。焊接热影响区的过热区已由马氏体转变为回火屈氏体,熔合线焊缝侧的类马氏体也已发生了回火,并在熔合线附近出现了增碳层。焊接接头的室温和高温瞬时强度高于母材,但其塑性韧性均较低,是裂纹萌生和扩展的薄弱部位,需加强运行监督。     

T92钢焊接接头的组织和韧性研究

通过硬度试验、冲击试验、断口扫描和金相组织脱察,研究了T92钢焊接接头的韧性与组织的关系.结果表明,焊缝的硬度值高,冲击功值低,其断口形貌与焊接热影响区的有显著差异,而焊缝金属组织中粗大的马氏体板条及板条束是导致焊缝韧性明显低于HAZ的主要因素之一.     

Effect of Heat Treatment on Microstructure and Hot Impact Toughness of Various Zones of P91 Welded Pipes

The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.     

搭接系数对S271钢镍基堆焊层热影响区组织与性能的影响

采用脉冲钨极氩弧焊在核电用S271钢表面堆焊镍基合金,研究不同搭接系数对堆焊接头热影响区微观组织和显微硬度的影响。结果表明:不同搭接系数下热影响区组织规律一致,第二道焊道未搭接区域紧邻熔合线处组织为粗大板条马氏体;搭接区域焊趾部位微观组织为M-A组元;第一道焊道未搭接区域紧邻熔合线处组织为回火马氏体。第二道焊道与搭接区域紧邻熔合线热影响区显微硬度高于460 HV,第一道焊道未搭接区域热影响区显微硬度低于460 HV;搭接系数为50%时,第二道焊道对第一道焊道未搭接区域的回火软化作用最为明显。     

含铜时效钢气体保护焊热影响区的组织与性能

研究了含铜时效钢气体保护焊热影响区的组织与性能。结果表明，在试验所用热输入范围内（1．2～2．3kJ／mm），含铜时效钢具有良好的焊接性能。焊接接头的拉伸强度同母材相比没有明显差异，且HAZ拉伸强度对热输入变化不敏感；焊接热影响区具有较高的冲击韧性，熔合线是HAZ中韧性最差的部位；和传统调质型船体用钢相比，含铜时效钢HAZ硬化和软化现象不明显；热输入对含铜时效钢粗晶区组织影响显著，随着热输入的增大，粗晶区组织由细板条贝氏体向粗大的粒状贝氏体转变。