1.4003铁素体不锈钢与耐候钢对接焊试验结果及分析

采用MAG焊对1.4003铁素体不锈钢与Q345NQR2耐候钢进行对接焊,通过对焊接接头进行力学性能试验、金相组织分析、显微硬度测试、冲击试验等,研究1.4003铁素体不锈钢与Q345NQR2耐候钢2种钢的焊接工艺。结果表明：1.4003铁素体不锈钢与Q345NQR2耐候钢对接接头的力学性能良好;焊缝显微组织为奥氏体+铁素体双相组织,对焊缝的力学性能有一定的改善;1.4003不锈钢侧热影响区为粗大的多边形铁素体晶粒,Q345NQR2钢侧热影响区为片层状珠光体组织+白色铁素体;焊缝组织主要为奥氏体,硬度有所升高,1.4003不锈钢侧粗晶区由于铁素体晶粒粗大,硬度有所下降;Q345NQR2耐候钢侧热影响区粗晶区为珠光体和残余奥氏体,硬度与焊缝的相差不大;对接接头室温和-40℃下的冲击性能均比较好。     

430不锈钢微束等离子弧焊接头的组织及耐腐蚀性能研究

采用微束等离子弧焊对1.2 mm厚的430不锈钢薄板进行对焊试验,通过分别改变焊接电流、焊接速度和离子气流量的单变量试验得到了优化的焊接工艺参数,研究了最优参数下接头的显微组织和耐腐蚀性能。结果表明:焊接电流为22 A,焊接速度为115 mm/min,离子气流量为0.6 L/min时,焊缝的成形效果最好。焊缝组织中马氏体被拉长,铁素体晶粒变得粗大,沿晶界方向还有碳化物条带。接头的耐腐蚀性能比母材的差。     

14NiCrM0106V与Q345E焊接接头组织与力学性能的研究

通过室温拉伸、弯曲、冲击、硬度试验及金相分析,对Q345E低合金钢与14NiCrM0 10 6V低合金钢混合气体保护焊焊接接头的力学性能与显微组织进行了研究.结果表明:采用ER50-6实芯焊丝焊接时,可以获得拉伸、弯曲和冲击性能均良好的焊接接头;焊缝区硬度较均匀,焊缝硬度在210～250 HV之间;焊接接头焊缝中心组织为先共析铁素体分布于柱状晶界上,晶内为针状铁素体与珠光体;Q345E侧熔合区组织为沿晶界析出块状先共析铁素体和向晶内生长的条状铁素体以及少量的珠光体和贝氏体;14NiCrMo10 6V侧熔合区和过热区组织为板条状马氏体和粒状贝氏体.     

Q345B和0Cr18Ni10Ti异种钢焊接工艺试验北大核心

分析了奥氏体不锈钢和低合金钢焊接接头性能的主要影响因素,选择了镍基合金焊接材料进行焊接试验,并通过焊缝力学性能和接头组织的分析,总结了采用镍基合金焊材焊接Q345B和0Cr18Ni10Ti异种钢的优点,试验结果表明:镍基合金可以实现低合金钢和不锈钢在性能上的过渡,在组织上可以得到网状和点状的铁素体组织,焊接接头性能优异。     

Q345/316L异种钢K-TIG焊接接头的组织及性能

采用K-TIG焊接方法对Q345/316L异种钢进行焊接试验,并利用光学显微镜、扫描电镜、万能试验机、冲击试验机、显微硬度仪等观察和分析焊接接头的显微组织及力学性能.结果表明:靠近316L侧焊缝组织为奥氏体及骨骼状铁素体,呈柱状晶分布,靠近Q345侧焊缝组织为板条马氏体.316L侧形成宽约45～50μm的熔合区,由细小的蠕虫状铁素体呈无方向且不连续的分布在奥氏体基体上.Q345侧熔合区产生魏氏组织,过热区晶粒粗大且有索氏体生成,相变重结晶区晶粒细小.拉伸断裂位置均发生在Q345侧母材.焊接接头冲击韧性良好,断裂位置均在Q345热影响区,断口为韧脆混合准解理断裂,有韧窝、河流花样、解理台阶.焊缝显微硬度明显高于两侧热影响区及母材.     

高强度304不锈钢薄板微弧等离子弧焊接头性能研究

采用微弧等离子弧焊对304不锈钢薄板进行焊接,研究填丝与否对焊接接头性能的影响。结果表明,填丝对等离子弧焊接头成形、显微组织和力学性能产生一定影响。相对而言,自熔焊焊缝宽度较宽,焊缝区组织较细小。自熔焊焊缝区显微组织由奥氏体和铁素体组成,在奥氏体基体上析出的骨架状铁素体和板条状铁素体含量相近。焊缝区显微硬度分布均匀,这种均匀分布导致接头强度相对较高,达到母材的84%。等离子弧填丝焊过程中,焊缝成分随填充焊丝改变,热输入增大,导致焊接接头性能稍微下降。但综合考虑高效和性能等因素,认为等离子弧填丝焊更适用于工业应用。     

SPA-H钢与304不锈钢异种钢焊接接头组织及性能研究

采用钨极氩弧焊对SPA-H钢与304不锈钢进行异种钢焊接,分析测试了不同焊接电流下焊接接头的显微组织、显微硬度和拉伸性能,研究了焊接电流对焊接接头组织及性能的影响。结果表明,随着焊接电流的增加,焊缝组织从定向生长的胞状晶和树枝晶到细化的胞状晶和树枝晶,再到粗大的等轴晶变化;SPA-H母材与焊缝之间存在明显的熔合线,而且随着焊接电流增加,熔合线由窄变宽;焊接接头中的硬度峰值都出现在焊缝区,电流为70 A时焊接接头焊缝和304侧热影响区的硬度值最高,但SPA-H侧热影响区的显微硬度显著低于焊缝区的显微硬度;电流为70 A的试样接头抗拉强度均高于60、80 A的焊接接头,60 A的试样接头抗拉强度和伸长率最低;三种焊接电流下的焊接接头抗拉强度均远高于母材,焊缝满足强度要求。     

金属的焊接性

9％Cr-1％Mo耐热钢熔敷金属中M-A组元的研究;微合金元素对00Cr12NiTi铁素体不锈钢焊接接头HAZ组织及力学性能的影响;低合金钢焊缝的针状铁素体微观组织;焊缝蠕变强度对马氏体／贝氏体异种钢接头界面蠕变损伤的影响;无钴马氏体时效钢电子束焊接接头组织与性能分析     

金属的焊接性

9％Cr-1％Mo耐热钢熔敷金属中M-A组元的研究;微合金元素对00Cr12NiTi铁素体不锈钢焊接接头HAZ组织及力学性能的影响;低合金钢焊缝的针状铁素体微观组织;焊缝蠕变强度对马氏体／贝氏体异种钢接头界面蠕变损伤的影响;无钴马氏体时效钢电子束焊接接头组织与性能分析     

Q345/316L异种钢焊接接头显微组织结构与力学性能北大核心CSCD

利用气体保护钨极氩弧焊(GTAW),采用ER309L和ER308两种焊丝对Q345/316L异种钢进行焊接试验,并利用光学显微镜、扫描电镜、万能试验机、冲击试验机、显微硬度仪等对焊接接头的显微组织结构及力学性能进行研究。结果表明:焊缝金属为奥氏体和铁素体组织,在Q345侧热影响区(HAZ)发现有明显的碳元素迁移现象,焊缝中Cr、Ni等合金元素成分迁移很小,稀释不明显;焊缝-316L交界处形成了宽约50μm的熔合区。ER309L焊接接头在强度、塑性、冲击韧性和显微硬度方面优于ER308焊接接头;同时,两者拉伸断裂均发生在Q345侧HAZ部位,接头焊缝冲击韧性良好,显微硬度高于两侧母材。     

FSS/ASS厚壁异种钢“TIG冷焊 + UNGW”组合焊的接头组织与力学性能

为了有效解决铁素体不锈钢的焊接热影响区晶粒易粗化问题，以及奥氏体不锈钢焊接时在接头部分熔合区及其附近热影响区内因易形成蠕虫状δ铁素体而显著降低该区域耐腐蚀性的问题，提出了“TIG冷焊 + UNGW”的组合焊接工艺，并进行了1Cr17/1Cr18Ni9Ti厚壁异种不锈钢的焊接，同时对所得接头的显微组织、力学性能及耐腐蚀性进行了测试与分析. 结果表明，组合焊接头的1Cr17母材热影响区晶粒未发生粗化，并且1Cr18Ni9Ti母材部分熔合区及其附近热影响区内未形成蠕虫状δ铁素体；组合焊接头的抗拉强度优于1Cr17母材，并且1Cr17母材热影响区的冲击吸收能量与1Cr17母材相当；组合焊接头的熔敷层、1Cr18Ni9Ti母材、1Cr17母材、UNGW焊缝区及完整接头的耐腐蚀性呈依次下降的趋势.     

铁素体不锈钢搅拌摩擦焊工艺及缺陷形成机理

采用钨铼合金搅拌工具对T4003铁素体不锈钢进行搅拌摩擦焊接工艺试验,研究搅拌摩擦焊缝成形、接头组织特征及缺陷形成机理.结果表明,不同旋转速度下随焊接速度增加,轴向压力呈单调增加趋势;当转速为150,250 r/min时,可获得无缺陷致密焊缝;当转速为350 r/min时,靠近前进侧的焊缝区出现孔洞缺陷,随着焊接速度和轴向压力不断增加,焊接缺陷有减少趋势.焊接接头焊核区发生了相变和明显淬硬现象,组织为细小等轴铁素体和低碳马氏体,焊缝具有明显不均匀硬度分布.提出了一种焊缝热塑性金属平衡流动模型分析其缺陷形成机理.     

GMAW-P工艺参数对TCS345不锈钢焊接接头缺口冲击韧度的影响

以TCS345铁素体不锈钢名义熔合线处的缺口冲击韧度为研究对象,采用一次回归正交试验,考察脉冲熔化极气体保护焊(pulse gas metal arc welding简称GMAW-P)脉冲工艺参数对名义熔合线处缺口冲击韧度的影响,分析脉冲电流、脉冲时间、脉冲频率、焊接速度及其交互作用对焊接接头名义熔合线缺口冲击韧度的影响规律.结果表明,TCS不锈钢焊接热影响区的组织为铁素体+马氏体.运用MATLAB优化函数对焊接工艺参数进行优化,优化结果为脉冲电流450A、脉冲时间2.3ms、脉冲频率250Hz、焊接速度500mm/min.     

真空室窗口领圈316L厚板电子束焊接接头不均匀性

真空室是未来聚变工程实验堆的核心部件,其组件窗口领圈采用能一次焊透50 mm以上不锈钢且变形较小的电子束焊进行拼焊. 为了深入探索厚板焊接接头不均匀性,在焊接过程中应用扫描偏转并对50 mm厚的316L奥氏体不锈钢焊接接头厚度方向的微观组织和硬度进行分析. 结果表明,焊缝组织由奥氏体和铁素体组成,从焊缝中心线附近,上层到下层焊缝组织由粗大的板条状/骨架状铁素体依次变为更加紧密排列的骨架状铁素体和等轴晶状铁素体;带有扫描偏转的焊接接头在焊缝厚度方向更早出现等轴晶;扫描偏转能改善焊缝表面成形质量;焊缝显微硬度从上层到下层逐渐增加.     

Microstructure and mechanical properties of underwater friction taper plug weld on X65 steel with carbon and stainless steel plugs

Underwater friction taper plug welding for X65 pipeline steel was performed using Q345 structural steel and 316L stainless steel plugs. Weld microstructures, defects formation and mechanical properties were investigated. Using Q345 plugs can produce defect free and overmatching welded joints whose impact toughness was also favourable. Lower bainite and lath martensite in the weld zone resulted in high hardness with maximum value up to 418?HV10. Using 316L plugs can significantly reduce weld zone hardness due to austenite dominated microstructure. Microcracks can easily emerge at and may propagate along γ–δ phase boundaries to form macrocracks. Intermittent cracks were found along the bonding interface of all the 316L plug welds, which should be caused by the relief of the residual stress.     

添加N2保护对CMT-P复合电弧焊接头组织与性能的影响

以UNS S32750超级双相不锈钢为研究对象,采用冷金属过渡脉冲(cold metal transfer pulse,CMT-P)复合电弧焊接技术,运用光学显微镜、扫描电子显微镜、透射电子显微镜、X射线衍射仪和电子探针组织表征手段以及显微硬度和低温冲击韧性性能测试方法,对比研究了纯Ar和Ar+2%N₂气体保护对焊接接头的微观组织、硬度和低温韧性的影响规律.结果表明,与纯Ar保护气相比,添加2%N₂保护的焊接过程飞溅较少,焊缝平整笔直,鱼鳞纹更加细致紧密.此外,热影响区主要由过量的铁素体和少量的奥氏体组成,并伴随有害的Cr₂N析出.因此,与CMT-P复合电弧焊接头的其它区域相比,热影响区的硬度较高和韧性较低.添加2%N₂气体保护增加了焊缝和热影响区奥氏体含量和N原子在铁素体与奥氏体内的固溶量,从而提高了接头各区域的低温韧性.     

Mechanical and corrosion properties of 445J2 ultra pure ferritic stainless steel joint

The microstructure, mechanical and corrosion resistance properties of 445J2 ultra pure ferritic stainless steel thin plate joints conducted by the pulsed current gas tungsten arc welding (PCGTAW) were discussed in this paper. In order to avoid weld defects, the appropriate welding process was adjusted. The joints were subjected to optical microscopy, transverse static tensile, plastic deformation, intergranular corrosion and electrochemistry corrosion tests. The results indicated that the weld zone (WZ) is characterized with columnar grains and equiaxed grains and the heat-affected zone (HAZ) shows coarse ferrite grains due to the rapid solidification of thin plate welding. The PCGTAW joint exhibited acceptable mechanical properties and equivalent corrosion resistance properties as the base metal.     

铜钢异种材料等离子弧焊接头性能

采用LHM-200等离子弧焊机对1 mm紫铜与低碳钢异种材料进行了熔透型等离子弧焊试验,得到了内部无缺陷、外观成形良好的接头.观察了接头的显微组织,并分析了工艺参数对接头力学性能的影响.结果表明,焊缝区中心显微组织呈细胞群状,界面两侧的组织特征呈现显著的不同,焊缝与铜侧界面没有明显的熔合线,局部呈漩涡状,钢侧与焊缝连接处出现了明显的分界线;最佳工艺为焊接电流为65 A,焊接速度为0.4 cm/s,离子气流量为0.7 L/min,此时接头抗拉强度可达176 MPa,试样断裂于铜母材热影响区.     

Microstructure and mechanical properties of E36 steel joint welded by underwater wet welding

The microstructure and mechanical properties of E36 steel joint welded by underwater welding using flux-cored wire are comprehensively investigated. The welding depth, welding current and welding voltage is 4 m, 130 A and 32 V, respectively. The weld metal is ferrite which varies in size, with carbide particles distributed on it, while the microstructure of HAZ is mixture of martensite of different size and some tempered structure. The microhardness of the weld metal is 190 HV. Almost all the tensile specimens fracture in weld metal and the average tensile strength of joint is 390 MPa, which is equal to 80% that of base metal. The tensile fracture morphology of joint presents obviously the characterization of brittle fracture, which displays the features of cleavage fracture and intergranular fracture.     

Microstructure and high temperature properties of the dissimilar weld between ferritic stainless steel and carbon steel

Dissimilar joints between STS441, a ferritic stainless steel, and SS400, a carbon steel, were welded by GMAW (Gas Metal Arc Welding) using STS430LNb as a welding wire. The fracture behavior of the dissimilar weld was analyzed by a microstructural observation and thermo-mechanical tests. Martensite was formed at the region between SS400 and the weld metal because the Cr and Nb content in this region decreased due to the dilution of SS400 carbon steel during welding. According to results from a high temperature tensile test with a specimen aged at 900 °C, it was found that the tensile strength of the dissimilar weld at high temperature was equal to that of STS441 base metal and the formation of martensite had little influence on tensile strength of the dissimilar weld at high temperature. However, in the case of thermal fatigue resistance, the dissimilar weld had an inferior thermal fatigue life to STS441 because of the presence of martensite and the softened region around the interface between the dissimilar weld metal and SS400.