E308焊条焊缝金属氧含量及其影响因素的试验研究

较低介绍了E308焊条焊缝金属氧含量的测试及结果,揭示了不同药皮类型和药皮含水量及不同焊缝金属锰含量,即不同药皮中金属锰加入量对焊缝金属中氧含量的影响规律。试验结果表明:试验4种药皮类型和11种E308焊条焊缝金属氧含量均在0.045%~0.112%范围内,氧含量较低;不同药皮类型和药皮含水量,在药皮中金属锰加入量相同情况下,对焊缝金属中氧含量无明显影响;焊缝金属中锰含量,即药皮中金属锰的加入量,对其氧含量的影响是明显的:随着锰含量的提高,其氧含量是减少的,反之则是增加的。因此,在设计E308焊条时,只要药皮中加入一定量的金属锰,即焊缝金属中锰含量大于1%时,就可减小焊缝金属中的氧含量,约0.075%。     

稀土氧化物对低合金钢焊缝组织与韧性的影响

通过正交试验方法设计9组以稀土氧化物为添加剂的碱性焊条药皮成分,研究了在焊条药皮中添加的稀土氧化物种类和添加量对低合金钢焊缝组织与低温韧性的影响。试验结果表明,适量氧化镧、氧化铈和氧化钇的混合添加剂具有改善焊缝组织和提高焊缝低温冲击韧性的作用,在药皮中添加w(La2O3)0.7%,w(Ce2O3)1.0%和w(Y2O3)0.3%时,其焊缝低温韧性相对最好;氧化钇对焊缝低温韧性的影响程度明显高于氧化镧和氧化铈,而氧化镧和氧化铈对焊缝低温韧性的影响规律和作用程度基本相同。     

手工电弧焊中磷在熔渣-熔敷金属两相间的分布

通过试验和理论分析，研究了手工电弧焊磷在熔渣和熔敷金属中的分配比。结果表明，焊条药皮的碱度或熔渣中提高，使Ｌｐ增加；虽然在改变焊条药皮组成和渣中ＦｅＯ量的情况下，焊缝金属的脱磷是有限的，但合适的药皮碱度和熔渣ＦｅＯ含量，焊缝金属还是可以获得较好的脱磷效果的。     

基于正交试验和RBF神经网络的焊缝低温韧性预测

通过正交试验获取样本数据,利用MATLAB的工具箱函数建立RBF神经网络预测模型,研究了稀土氧化物对焊缝低温韧性的影响和作用程度。结果表明,通过正交试验样本训练的RBF神经网络较好地反映稀土氧化物与焊缝低温韧性之间的非线性关系,可用于焊缝低温韧性预测;在焊条药皮中的氧化镧和氧化铈添加量较高,而氧化钇添加量较低时其焊缝低温韧性相对较好,当添加0.7%氧化镧、1%氧化铈和0.3%氧化钇的焊条其焊缝低温韧度值达到98 J/cm~2。     

稀土氧化物对碱性焊条焊缝组织与低温韧性的影响

在典型碱性结构钢焊条药粉成分基础上,以镧、铈及钇的混合氧化物作为焊条药粉添加剂,设计了六组含稀土氧化物碱性焊条,观察了焊缝显微组织和冲击断口形貌特征,测定了焊缝低温冲击韧性。结果表明,在焊条药皮中适量添加稀土氧化物可细化焊缝金属晶粒,而且有利于形成强韧性较好的针状铁素体组织;适量添加稀土可提高焊缝低温冲击韧性,当焊条药粉中的稀土氧化物添加量为2.0%时,低温冲击韧性相对最好,冲击吸收功为56.66 J,其冲击断口韧窝较密集,韧性断裂特征明显。     

高强焊条药皮碱度对韧性与扩散氢的影响

通过使用钛硼微合金化以获得韧性组织焊缝、提高焊条药皮碱度以净化焊缝等手段,可使屈服强度级别为785MPa的手工焊条熔敷金属-50℃冲击吸收功AKV平均值超过80J.但焊条药皮碱度过高时,AKV(-50℃)值没有明显增加,而且对降低熔敷金属扩散氢不利.采用对焊条药皮原材料进行分类高温去水处理,对成品焊条多次烘干吸湿烘干处理后,反复测定.结果表明,当焊条药皮碱度在2.2～2.4之间时,熔敷金属可同时具有高屈服强度、高低温冲击吸收功及超低扩散氢.     

元素B对自蔓延焊条焊接工艺及接头显微组织影响

研究了元素B的不同添加量对铜基自蔓延焊条焊接工艺性和焊接接头显微组织的影响。试验结果显示,元素B的适量加入可以降低自蔓延焊条燃烧速率、抑制反应喷溅,并具有改善焊缝金属组织和细化晶粒的作用。在最佳添加量0.5%B时,焊缝脱渣良好,液态金属铺展均匀,焊缝气孔率显著降低;焊缝金属无明显宏观偏析,且晶粒细小均匀。当B加入量高于1.0%时,焊条工艺性能急剧恶化,焊缝金属发生严重宏观偏析,形成明显的富Fe区和富Cu区,元素B与合金元素化合形成硬质相,弥散分布于富Fe区,过剩B偏析于晶界,增加了焊缝金属的裂纹敏感性。     

稀土低合金耐磨钢堆焊焊条熔敷层性能研究

通过扫描电镜、能谱分析、磨损试验系统地研究了熔敷层金属化学成分、耐磨性、冲击断口形貌.试验结果表明,同等条件下,焊条药皮中添加稀土氧化物可以提高熔敷层耐磨性能;药皮配方中添加质量分数为1.5%的氧化铈的耐磨性强于添加1.5%的氧化钇的耐磨性.     

稀土对高效铁粉焊条焊缝组织及性能的影响

通过对普通铁粉焊条药皮成分进行调整,并加入稀土添加剂研制出了一种新型含稀土高效铁粉焊条.对试件冲击断口的扫描电镜分析,采用IA3001型图像分析仪对焊缝金属夹杂物分析,以及通过低温冲击试验,证实了适量的稀土可起到细化晶粒,净化焊缝的作用.所研制的稀土高效铁粉焊条工艺性能良好,焊缝金属低温韧性好,可用于重要结构的焊接.     

Si和Cu元素对铝-镀锌钢GTAW接头性能的影响

通过填加4种不同的焊丝,在焊缝中加入不同含量的Si,Cu元素,进行了5A02铝合金和镀锌钢板之间异种金属的钨极氩弧焊(GTAW)搭接试验.试验发现Cu元素含量高于一定值时,金属间化合物层厚度大于10μm,而当Cu元素含量较低时,随着Si元素加入量的增加,金属间化合物层的厚度减小,最小约为2μm.当Si元素含量大于5%时,抗拉强度接近136 MPa.但此时,制约焊缝性能的主要因素是焊缝根部出现的气孔聚集缺陷.另外,Si元素的加入还可以改善焊缝与铝合金母材连接处柱状晶区的组织.     

稀土氧化钇对高强度钢焊条熔敷金属组织和性能影响

基于Ni-Cr-Mo-V合金体系,研究了稀土氧化钇对800 MPa高强度钢焊条焊缝微观组织和性能的影响.结果表明,Y₂O₃含量在0~0.02%范围内变化时,随着Y₂O₃含量的增加,焊缝熔敷金属组织中先共析铁素体逐渐降低,针状铁素体含量逐渐增加,强度和低温冲击韧性均逐渐增加,且当Y₂O₃含量为0.02%时,焊缝熔敷金属低温冲击韧性达到最大值;当Y₂O₃含量超过0.02%时,焊缝熔敷金属组织中针状铁素体含量下降,低温冲击韧性降低.综合考虑上述因素,该高强度钢焊条中Y₂O₃最佳添加量为0.02%左右.     

X80管线钢焊条电弧焊接头组织与耐蚀性分析

利用双熔敷极焊条电弧焊技术对X80管线钢进行了焊接,并在焊接接头成分、组织及耐蚀性方面与传统焊条电弧焊进行了对比分析.结果表明,双熔敷极焊条电弧焊技术熔敷效率高,但受其结构及药皮重量系数的影响焊缝中合金元素的含量比普通焊接焊缝的低,且焊缝中多边形铁素体含量较高,另一方面由于对母材的热输入较低,使得其粗晶区组织较为细小,这有利于其性能的提高;对0.5 M Na₂CO₃-1 M NaHCO₃溶液及通饱和CO₂的NACE A溶液中的耐蚀性研究发现,焊缝及粗晶区耐蚀性均差于母材,且采用双熔敷极焊条电弧焊技术有利于提高焊缝及粗晶区的耐蚀性.     

Effect of slag variations on ANSI/AWS A5.1–91 E6013 electrode properties: replacement of TiO2 in electrode coating with MnO,FeO, CaO,MgO, K2O,or Na2O

Abstract

The present work is part of a research programme to study the effect of variation of the coating composition of covered rutile manual electrodes on both operational and deposited weld metal properties. According to previous results obtained for rutile electrodes, an increase of slag basicity, achieved through modifications in the coating, produces an improvement of the impact properties of the deposited weld metal, as well as a decrease in the diffusible hydrogen, along with beneficial changes in the operational properties of the electrode. The aim of the present work is to study the influence of the replacement of titanium oxide with oxides of alkali metals (sodium and potassium), alkaline earth metals (calcium and magnesium), and iron and manganese oxides in the coating of an ANSI/AWS A5.1–91 E6013 type electrode on the operational characteristics of the electrode and the microstructure, mechanical properties, and diffusible hydrogen content of the electrode weld metal. Tensile strength and Charpy V notch impact properties were measured in the all weld metal samples produced using each of the seven electrodes designed for the present study. A cross-section from each coupon was used to determine the chemical composition of the deposit and to carry out a metallographic study using a light microscope. As a result of the addition of different oxides, changes in the operational properties were observed using both direct and alternating current, as well as a decrease in the diffusible hydrogen content in the weld metal. Also, electrodes in which rutile was substituted by sodium oxide in the coating showed an improvement in the impact properties of the deposit.     

保护气体对440MPa HSLA钢GMAW焊缝组织及韧性的影响

采用不同保护气体对440 MPa级低合金高强钢(HSLA钢)进行气保焊焊接,通过光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和电子背散射衍射技术(EBSD)对焊缝微观组织及夹杂物形貌进行了观察,研究了保护气体组成对焊缝组织及韧性的影响,并分析了不同成分保护气体对焊缝夹杂物大小、数量及其成分的影响.结果表明,保护气体为100％ CO2,焊缝金属韧性较差;保护气体(体积分数)为80％ Ar+20％ CO2和90％ Ar+ 10％ CO2,焊缝金属韧性较好.100％ CO2气体保护焊焊缝组织主要为铁素体和贝氏体,混合气体保护焊(20％ CO2和10％ CO2)焊缝组织主要为针状铁素体和少量侧板条铁素体.随着保护气体中CO2含量的减少,焊缝金属中夹杂物数量、尺寸均降低,且成分发生变化.对于440 MPa级HSLA钢,合理的保护气体组成可以得到良好的焊接质量.     

Special features of heating and melting electrodes with an exothermic mixture in the coating

Experimental results show that exothermic reactions in the heating and melting stages of electrode coating take place when the coating contains more than 35% of the exothermic mixture. Data for the effect of the amount of exothermic mixture in the electrode coating on heating and melting of the electrodes are presented. The thermal balance of melting the electrodes with the exothermic mixture in the coating is calculated. The results show that the temperature of 1273 K at which the efficiency of the exothermic reaction is high is reached at a distance of approximately 1 mm from the electrode tip. It is confirmed that the addition of up to 53.4% of the exothermic mixture to the electrode coating increases the effective efficiency of heating the parent metal (η_m) from 0.715 to 0.815 and of the electrode (η_el) from 0.28 to 0.415.     

Effect of oxygen-containing additives on weld penetration in self-shielded flux cored arc welding

The effect of Fe₂O₃ and Li₂CO₃ additives in flux core on the weld metal oxygen content and weld penetration in self-shielded flux cored arc welding were studied schematically. The result shows that the oxygen content in the weld metal and weld penetration both increased with the Fe₂O₃ addition increased in the range of 5wt.% to 20wt.% . The oxygen content in the weld metal was increased with the Li₂CO₃ addition increased in the range of 1wt.% to 8 wt.%. However, the weld penetration decreased when Li₂CO₃ addition exceeding 4 wt.%. High-speed photographic images show that when Fe₂O₃ addition in flux core exceeding 15wt.%, droplet became excessively large, so that spatters were frequently generated in large numbers. In this study, Fe₂O₃ and Li₂CO₃ in the amount of 11wt.% and 4wt.%, respectively, jointly added in the flux core can achieve a deeper weld penetration with sound usability characteristics.     

添加CeO_2对MoS_2基复合涂层摩擦学性能的影响

针对MoS_2基复合涂层耐磨性差和承载能力低的问题,以不同含量(质量分数)的CeO_2作为添加剂,采用喷涂法在GCr15钢表面制备MoS_2基复合涂层。利用摩擦磨损试验机和划痕仪分别研究涂层摩擦磨损性能和结合强度,并借助金相显微镜对涂层磨损形貌进行表征。结果表明:添加适量CeO_2可以改善涂层的摩擦磨损性能,其最佳含量为2%,此时摩擦因数和磨损量均最小,分别为0.232和0.011 3 mm~3;同时结合强度从22 N提高到28.29 N。涂层磨损量随载荷的增大而增大;而载荷小于8 N时,涂层的摩擦因数随载荷的增大而减小,当载荷大于8 N时,摩擦因数又有回升趋势。添加稀土后涂层的承载能力有明显提高。未添加稀土时,涂层产生严重剥离,并发生磨粒磨损;添加2%CeO_2后,涂层发生轻微磨粒磨损,耐磨性得到显著提高。     

关于消除蒙乃尔合金焊条焊接气孔问题的研究

本文对钛型渣系(TiO_2—CaF_2)、无氧涂料渣系(CaF_2—CaO—TiO_2)及低氢型渣系(CaO—CaF_2—SiO_2)的蒙乃尔合金焊条在焊接时产生气孔的主要原因与机理进行了研究。试验表明,加强涂料中的脱氧、脱氮及去氢是消除气孔的重要途径。蒙乃尔合金手工电弧焊接中,氮与氢是促成焊缝产生气孔的主要因素。因此,应当在涂料中加入较强的脱氮物质(如钛、铝等),焊条要严格烘干,并注意加强熔渣反应中的去氢作用。焊条熔渣的物理性能直接影响焊缝表面气孔的形状和数量。合理的焊接工艺参数对消除蒙乃尔合金焊接气孔是有效的,如用较低的电弧电压,稍慢的焊接速度,大型工件进行预热都有利于焊缝中气体的排除。     

Erosive Wear Study of Rare Earth-Modified HVOF-Sprayed Coatings Using Design of Experiment

In the present study, the effect of CeO₂ addition in 1006 powder coatings on microstructure, microhardness, and high-temperature erosion resistance were studied. The CeO₂ addition refines microstructure, forms new phases, and increases microhardness of HVOF-sprayed coatings. The erosive wear behavior of coatings were investigated by Response Surface Methodology (RSM). To investigate and develop an erosive wear model of unmodified 1006 (without CeO₂) and modified 1006 (CeO₂ addition) coatings’ four factors: velocity, impact angle, temperature, and feed rate, each factor at three levels were used. ANOVA was carried out to determine the significant factors and interactions. Thus, an erosive wear model was developed in terms of main factors and their significant interactions. A comparison of modeled and experimental results showed 4-7% error. The modified 1006 coating showed high erosive wear resistance as compared with unmodified 1006 coating. This is due to increase in hardness and refined microstructure of the modified 1006 coating.     

Influences of ceria and yttrium on properties of D127 surfacing electrode

The coating of D127,a surfacing electrode,was added ceria(CeO_2) and yttrium (Y) for possible enhanced electrode properties.The method of orthogonal test was adopted.The coating with different amount of CeO_2 and Y was pressed.The hardness of surfacing layer was carried on by hardness tester,microstructure was investigated by metallograph,and the content of rare earths was analyzed by X-ray energy dispersive spectrometer.The results show that the microstructures of deposited metal can be effectively made fine,accordingly,the hardness and the wear-resistance of deposited metal are also raised.But the addition amount of the rare-earth should be proper.The deposited metal microstructure is the finest and the most homogeneous when the addition amount of CeO_2 is 2 wt.% and Y 1.2 wt.%,and the hardness of the surfacing layer is the highest.