电子束焊工艺对304不锈钢焊缝的抗晶间腐蚀性能影响

采用3种不同的电子束焊接工艺焊接304不锈钢,通过显微组织观察、XRD分析、极化曲线测试、动电位再活化(EPR)试验研究了不锈钢焊缝的抗晶间腐蚀性能.结果表明:减少焊接热输入量和添加熔入性焊丝这两种方法都能减少电子束焊缝中铬的碳化物的析出,降低焊缝的敏化度,提高焊缝的抗晶间腐蚀性能;与减少焊接热输入量相比,添加熔入性焊丝对晶间腐蚀的影响更大,焊缝抗晶间腐蚀性能提高更显著.     

焊接工艺对2205双相不锈钢焊接接头综合性能的影响

采用等离子弧焊打底 TIG焊盖面及等离子弧焊打底 MIG焊盖面焊接工艺焊接了2205双相不锈钢,研究了2205双相不锈钢的焊接性,并对焊后固溶处理与未进行固溶处理的焊件组织特征、力学性能及抗腐蚀性进行了比较,研究了不同焊接热输入和固溶处理工艺对焊接接头综合性能的影响.     

304不锈钢法兰焊接裂纹分析及返修

对检修过程中发现的304不锈钢焊缝裂纹及母材本体裂纹进行分析,焊缝存在较多的焊渣,以及根部未焊透是焊缝开裂的原因。母材的金相分析表明,304不锈钢晶界存在碳化物聚集,容易发生晶间腐蚀,引起母材开裂,焊接过程中,多层多道焊也容易使得热影响区晶间腐蚀加剧,引起母材开裂。304不锈钢锻造法兰的制造过程中应避免在敏化温度停留时间过长,固溶处理时应采取快冷的方式避免晶间腐蚀。焊接返修过程中,通过严格控制焊接层间温度,采用快速小热输入的工艺参数使得返修后的304不锈钢焊接质量检验合格。     

超级双相不锈钢多层多道焊接接头组织及腐蚀性能

选用2507超级双相不锈钢作为研究对象,研究钨极氩弧焊多层多道焊接接头的组织和腐蚀性能.采用两种不同保护气进行钨极氩弧焊,主要讨论焊接道次和氮气添加对组织和腐蚀性能的影响.结果表明,焊缝中心均有较高的奥氏体含量,其腐蚀速率是焊根部位的0.68倍;盖面和焊根奥氏体含量相近,但盖面由于其弥散且尺寸相对较大的晶内奥氏体表现出更好的耐腐蚀性,焊根是焊缝金属的薄弱区域.混合区由于热影响区的存在腐蚀速率最快.保护气中氮气的添加促进了奥氏体的生成,降低了腐蚀电流密度一个数量级,提高了整体的腐蚀性能.     

The Microstructure and Pitting Resistance of Weld Joints of 2205 Duplex Stainless Steel

2205 duplex stainless steel (DSS) was welded by submerged arc welding. The effects of both heat input and groove type on the ferrite/austenite ratio and elemental diffusion of weld joints were investigated. The relationships among welding joint preparation, ferrite/austenite ratio, elemental diffusion, and pitting corrosion resistance of weld joints were analyzed. When the Ni content of the weld wire deposit was at minimum 2–4% higher than that of 2205 DSS base metal, the desired ratio of ferrite/austenite and elemental partitioning between the austenite and ferrite phases were obtained. While the pitting sensitivity of weld metal was higher than that of base metal, the self-healing capability of the passive film of weld metal was better than that of the base metal when a single V-type groove was used. Furthermore, the heat input should be carefully controlled since pitting corrosion occurred readily in the coarse-grained heat-affected zone near the fusion line of welded joints.     

2205双相不锈钢的激光-MIG复合焊接头性能

常规的高能束焊接方法因焊后冷速较快易导致双相不锈钢焊缝及热影响区两相比例失衡,接头性能恶化.采用激光-MIG复合焊接方法对2205双相不锈钢进行焊接,焊后对接头微观组织、力学性能和腐蚀性能分析发现,焊缝及热影响区铁素体相比例控制在40%～70%合理范围内,接头硬度和抗拉强度高于母材,焊缝、熔合线、热影响区的～40℃冲击...     

Assessment of Stress Corrosion Cracking Resistance of Activated Tungsten Inert Gas-Welded Duplex Stainless Steel Joints

The stress corrosion cracking behavior of duplex stainless steel (DSS) weld joint largely depends on the ferrite-austenite phase microstructure balance. This phase balance is decided by the welding process used, heat input, welding conditions and the weld metal chemistry. In this investigation, the influence of activated tungsten inert gas (ATIG) and tungsten inert gas (TIG) welding processes on the stress corrosion cracking (SCC) resistance of DSS joints was evaluated and compared. Boiling magnesium chloride (45 wt.%) environment maintained at 155 °C was used. The microstructure and ferrite content of different weld zones are correlated with the outcome of sustained load, SCC test. Irrespective of the welding processes used, SCC resistance of weld joints was inferior to that of the base metal. However, ATIG weld joint exhibited superior resistance to SCC than the TIG weld joint. The crack initiation and final failure were in the weld metal for the ATIG weld joint; they were in the heat-affected zone for the TIG weld joint.     

双相不锈复合钢板埋弧自动焊

研究了Ｈ１１／Ｘ２ＣｒＮｉＭｏＮ２２．５双相不锈复合钢板埋弧自动焊工艺，焊接材料的选择及其焊接性。结果表明，复层焊缝的δ铁素体含量在３５％～４５％内，其焊接性优良。过渡层的焊接采用较弱焊接规范和单道焊工艺，以控制较小的稀释率和良好的焊缝成形，防止在与基层焊缝的熔合线附近产生大量马氏体组织和其它硬化相。Ｈ１１／Ｘ２ＣｒＮｉＭｏＮ２２．５双相不锈复合钢板埋弧自动焊焊接接头具有良好的力学性能，复层焊缝具有极为优良的抗晶间腐蚀和应力腐蚀的能力。本研究为煤气工程中汽化炉的制造选定了合适的焊接材料并制定了最佳埋弧自动焊工艺。     

碳钢焊接接头腐蚀行为分析

通过对焊接接头各区域显微组织观察以及开路电位、极化曲线和电偶腐蚀电流的测量,研究了两种热输入所得焊接接头各区域的腐蚀行为. 结果表明,热输入小的接头各区域耐蚀性由小到大依次为母材,焊缝,热影响区;热输入大的接头各区域耐蚀性由小到大依次为母材,热影响区,焊缝. 该结果与接头不同区域的显微组织相关. 两种接头总腐蚀速率相比,热输入大的接头耐蚀性较好.     

Evaluation of the effect of heat input in superduplex stainless steel deposition by the plasma powder process*

Plasma powder surfacing is one of the latest processes for application of coatings, with control of dilution as its main feature. Surfacing with superduplex stainless steels is an interesting option for the construction and repair of equipment for applications in a highly corrosive environment, allowing the desired characteristics to be achieved: corrosion resistance and good mechanical properties. The aim of this work is to assess the ferrite content in the weld metal and the mechanical characteristics via microhardness profiles in surfacing of C-Mn steel pipes with deposition of UNS S32760 by plasma powder surfacing. Welding operations were carried out on pipes with deposition of SDSS, employing three welding heat input levels, varying the welding speed or the welding current. Then the geometry was analysed, the ferrite content in the weld metal was quantified and the microhardness profile was recorded. Variation in welding heat input caused changes in weld bead geometry, with variation in the welding current producing the most significant changes. Increase in heat input caused decrease in ferrite content of the weld metal. Regarding microhardness, only the condition with a higher level of welding current gave sufficiently high levels of microhardness in the weld metal.     

线能量对2205双相不锈钢焊接接头耐蚀性和韧性的影响

针对2205双相不锈钢材料，研究了线能量对其焊接接头耐蚀性和冲击韧度的影响，推荐出了12．7mm壁厚材料的焊接线能量范围，且用于某天然气管道T程现场焊接。     

硝酸级(NAG)310L不锈钢焊接接头在含Cr~(6+)的HNO_3溶液中的耐蚀性

对硝酸级(NAG)310L不锈钢焊接接头在含氧化性离子的沸腾硝酸中进行浸泡实验及金相分析。研究表明,在不同Cr~(6+)含量的沸腾40%HNO_3中,材料的腐蚀程度主要受Cr~(6+)含量的影响。随Cr~(6+)含量的增加,母材和焊缝均出现不同程度腐蚀,但焊缝较母材腐蚀严重。Cr~(6+)含量是促进焊缝过钝化腐蚀和晶间腐蚀的主要因素。     

Effect of welding speed on microstructure and corrosion resistance of Al–Li alloy weld joint

The corrosion resistance of a weld has a great impact on the service life of the joint. Changes in welding parameters can cause changes to the heat input, which affect the formation of the weld bead and the precipitation of the second phase, which determines the corrosion resistance of the weld. In this paper, the effect of a change in the welding speed on 2195 aluminium–lithium (Al–Li) alloy joints welded by laser and metal inert gas (laser-MIG) hybrid welding using Al–Si welding wire was studied. The macrostructure and microstructure of the weld were characterized by optical microscopy, X-ray diffraction, and scanning electron microscopy. The results show that the predominant precipitates in the laser-MIG hybrid welded Al–Li alloy were the θ (Al₂Cu) and T (Al–Li–Si) phases. As the welding speed increased from 11.5 mm/s to 16.5 mm/s, the heat input decreased, and the amount of the precipitated phase increased. Intergranular corrosion and electrochemical experiments were carried out on the weld seam, and the corrosion resistance was tested. With increasing welding speed, the corrosion resistance of the weld decreased. The high potential of the precipitated phase decreased the corrosion resistance of the weld joint.     

Microstructure and Mechanical Behavior in Dissimilar SAF 2205/API X52 Welded Pipes

The welding of a duplex stainless steel SAF 2205 DSS(UNS 31803) and high strength low alloy steel API X52 by shielded metal arc welding process was conducted using two different filler metals,the duplex E2209 and austenitic E309 grade.The microstructures of the dissimilar metal joints have been investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectroscopy(EDS) and X-ray diffraction.EDS analysis at the interface X52 weld metal showed an evident gradient variation of Cr and Ni between boundaries of fusion and type II,where the highest hardness value was recorded.Tensile strength and toughness values of the weld metal produced by E309 electrode are slightly higher than those of the weld metal produced by E2209 electrode.Potentiodynamic polarization tests of different regions of the welded joints evaluated in 3.5%NaCl solution exhibit a high corrosion resistance of both weld metals.     

Laser welding of AA 5083 samples by high power diode laser

Abstract

Laser welding is a very attractive technique to join different alloys at the industrial level, due to its low heat input, high flexibility, high weld quality and high production rate. In this work, the weldability of the aluminium alloy AA 5083 with a high power diode laser has been tested. Concisely, samples were subjected to lineal treatments of laser radiation, with the objective of studying the properties of the bead on plate welds generated. The main objective of the present work has been to study the influence of both the processing rate and the superficial treatment of the AA 5083 samples, on the morphological, microstructural and corrosion properties of the laser weld beads. The sizes of the welds were higher as the processing rate was decreased. The weld beads were seen to have better behaviour against corrosion than the base metal due to the microstructural refinement. It was also verified that a blasting process before processing gave beads with lower size but better corrosion resistance than the application of a black layer, due to the minimisation of the magnesium evaporation in this former superficial treatment.     

双相不锈钢焊接接头的耐腐蚀性能

根据母材临界点蚀温度(CPT)的试验结果,利用小试样的腐蚀实验方法研究了奥氏体-铁素体双相不锈钢焊接接头的耐点蚀性能.结果表明,手工电弧焊工艺过程对双相不锈钢材料的耐点蚀性能具有显著的影响,点蚀优先发生在焊缝金属或焊接热影响区中.双相不锈钢材料的耐点蚀性能与材料本身奥氏体和铁素体相比例有关.腐蚀试样的表面状态(粗糙程度)对母材金属的耐点蚀性能有明显的影响.表面越粗糙,耐点蚀性能越差,临界点蚀温度越低.     

冷却速率对高氮钢焊缝组织和性能的影响

研究了水冷和空冷条件下高氮不锈钢焊缝金属微观组织和力学性能的变化规律,讨论了冷却速率对高氮不锈钢焊缝微观组织和力学性能的影响规律. 结果表明,冷却速率增加能够有效增加高氮钢焊缝金属中的氮含量,尤其对于含氮量0.85%的高氮含量焊丝,增氮效果更明显. 冷却速率增加对高氮钢焊缝金属抗拉强度提高程度取决于焊丝中的氮含量,对于低氮含量高氮钢焊丝,冷却速率增加能够显著提高焊缝金属抗拉强度,当焊丝中氮含量超过0.58%时,冷却速率增加对焊缝金属抗拉强度影响不大,最终接头强度达到850 MPa.     

双相不锈钢焊接接头的耐蚀性研究

综述了双相不锈钢的焊接接头的耐蚀性研究进展及采用的研究方法和已取得的成果。主要介绍了双相不锈钢在焊接过程中,不同的热处理方式、不同的焊接工艺给双相不锈钢焊接接头的耐蚀性带来的影响。结果表明,采用合适的输入热能量、多层焊接、Ar＋2％N2混合保护气、手工电弧焊（SMAW）和钨极氩弧焊（TIG）相配合,可以使得焊接接头具有优良的耐蚀性能。     

影响P92钢焊缝冲击韧性的焊接工艺

P92钢是新型铁素体耐热钢,已广泛应用于超(超)临界燃煤发电机组。相比其他铁素体耐热钢,P92钢具有更高的高温强度和蠕变性能,其抗热疲劳性、热传导系数和热膨胀系数远优于奥氏体不锈钢,抗腐蚀性和抗氧化性优于其他9%Cr的铁素体耐热钢。P92钢的焊接技术已较为成熟,但其焊接接头易出现焊缝冲击韧性偏低的问题。影响P92钢焊缝金属冲击韧性的主要因素是焊接热输入。细焊条、薄焊层、多层多道焊,适当的预热温度、层间温度,足够的高温回火温度和恒温时间,是保证焊缝冲击韧性的有效措施。     

Microstructural and Electrochemical Evaluation of Fusion Welded Low-Nickel and 304 SS at Different Heat Input

The present research study investigates the effect of heat input using E 308 electrode (controlled by welding current, i.e., 70, 85 and 100 A) on microstructure, mechanical properties and corrosion behavior of low-nickel and 304 stainless steel (SS) weldments produced by shielded metal arc welding technique. SEM investigation shows that with the higher heat input, δ-ferrite content was reduced. Dendrite and inter-dendritic length is also reduced by lowering the heat input. For all the heat inputs, it is observed that δ-ferrite content was higher in 304 stainless steel (SS) as compared to that of low-nickel austenitic stainless steel (Cr-Mn SS). Considering the heat input for Cr-Mn SS, coarse grains were observed in the heat-affected zone region. For low heat input (LHI), tensile fracture surface has exhibited river-like pattern with dimple appearance. Corrosion studies show better pitting resistance for low heat input (LHI) samples due to higher δ-ferrite present in the weld region. Similarly, higher interphase corrosion resistance is observed in both the SS grades causing more dissolution in the LHI samples.