SAF2205双相不锈钢冷却管束的焊接

从探讨氧氯化反应器冷却管束国产化制造过程中SAF2205双相不锈钢的焊接问题入手，着重分析和制定了双相钢焊接工艺方案和质量保证措施，完成了SAF2205双相不锈管束的国产化研制，并且运行正常。     

Microstructure Evolution of a Cold-rolled 25Cr-7Ni-3Mo-0.2N Duplex Stainless Steel during Two-step Aging Treatments

A cold-rolled 25Cr-7Ni-3Mo-0.2N duplex stainless steel(DSS)has been aged in two steps.Firstly,the aging treatment at interval of 50℃ in a temperature range from 900 to 1050℃ was carried out in order to obtain fine grains.Secondly,another aging treatment at 850 ℃ was performed to reveal theσ-phase precipitation behavior.A detailed microstructure evolution during those two aging steps was observed by the optical microscope(OM),the scanning electron microscope(SEM),the electron backscatter difraction(EBSD)and the transmission electron microscope(TEM).The results revealed that the micro-duplex structure with grain size of lower than 10μm appeared after the first aging step.However,their grain size was rapidly increased with increasing aging temperature.Meanwhile,theδ→γand/orδ→γ+σtransformations took place in association with the occurrence of the extensive recovery or a little recrystallization inδ-grains.During the second aging treatment,σ-phase mainly nucleated atδ/γinterfaces and further grew along those interfaces into various morphologies(e.g.,butterfly and granule).A novel precipitation behavior was found in this study that theγ-grain boundaries bulged not only into theδ-grains as usual,but abnormally into theσ-phase precipitates without the prior precipitation of the isolated secondary austeniteγ2or another phases.     

SAF2205双相不锈钢焊接热影响区在尿素介质中的腐蚀研究

研究了SAF2205双相不锈钢和尿素级316不锈钢对接焊热影响区在工业尿素合成介质中的耐蚀性.实验结果表明,焊接线能量对热影响区的耐蚀性有重要影响,腐蚀最重处是在距离熔合线3-6mm区域,局部腐蚀深度随线能量的增加而增大.SAF2205不锈钢焊接线能量对热影响区腐蚀的敏感程度比316L不锈钢大.     

焊接方法对双相不锈钢焊接接头耐蚀性的影响

采用气体保护钨极氩弧焊（GTAW）、焊条电弧焊（SMAW）和埋弧焊（SAW）对2205双相不锈钢进行焊接,采用光学显微镜对接头组织进行观察,采用数点法计算铁素体相的含量,测定接头的耐点蚀和耐CO2应力腐蚀性能,研究焊接方法对接头耐蚀性的影响。结果表明,焊接方法影响焊缝组织形态及铁素体含量。GTAW焊缝由不规则的条状组织和两相交织分布的块状组织组成,而SMAW和SAW焊缝为方位不一的条状组织和少量的块状组织。GTAW和SMAW焊缝的铁素体含量为35％～55％,而SAW的不足20％。接头的耐蚀性与铁素体相比例密切相关,GTAW、SMAW和SAW的耐蚀性依次降低。从铁素体相比例和耐蚀性角度考虑,GTAW和SMAW能够获得满意的焊接接头。     

Microstructure and mechanical properties of dissimilar welds between 16Mn and 304L in underwater wet welding

Dissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal.     

2205双相不锈钢与304奥氏体不锈钢的焊接

采用焊条电弧焊(SMAW),以E2209作填充材料对2205双相不锈钢与304奥氏体不锈钢异种金属焊接工艺进行研究,通过优化焊接工艺参数,获得了具有良好力学性能和合适双相比例的焊接接头.接头力学性能测试表明,拉伸试样断裂发生在强度相对较低的304母材侧;2205母材侧热影响区的显微硬度值高于焊缝和2205母材,而304...     

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.     

Microstructure and pitting corrosion of similar and dissimilar stainless steel welds

Abstract

Pitting Corrosion behaviour of similar and dissimilar metal welds of three classes of stainless steels, namely, austenitic stainless steel (AISI 304), ferritic stainless steel (AISI 430) and duplex stainless steel (AISI 2205), has been studied. Three regions of the weldment, i.e. fusion zone, heat affected zone and unaffected parent metal, were subjected to corrosion studies. Electron beam and friction welds have been compared. Optical, scanning electron microscopy and electron probe analysis were carried out to determine the mechanism of corrosion behaviour. Dissimilar metal electron beam welds of austenitic–ferritic (A–F), ferritic–duplex (F–D) and austenitic–duplex stainless steel (A–D) welds contained coarse grains which are predominantly equiaxed on austenitic and duplex stainless steel side while they were columnar on the ferritic stainless steel side. Microstructural features in the central region of dissimilar stainless steel friction welds exhibit fine equiaxed grains due to dynamic recrystallisation as a result of thermomechanical working during welding and is confined to ferritic stainless steel side in the case of A–F, D–F welds and duplex stainless steel side in the case of D–A welds. Beside this region bent and elongated grains were observed on ferritic stainless steel side in the case of A–F, D–F welds and duplex stainless steel side in the case of D–A welds. Interdiffusion of elements was significant in electron beam welding and insignificant in friction welds. Pitting corrosion has been observed to be predominantly confined to heat affected zone (HAZ) close to fusion boundary of ferritic stainless steel interface of A–F electron beam and D–F electron beam and friction weldments. The pitting resistance of stainless steel electron beam weldments was found to be lower than that of parent metal as a result of segregation and partitioning of alloying elements. In general, friction weldments exhibited better pitting corrosion resistance due to lower incidence of carbides in the microstructure.     

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.     

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...     

超纯铁素体Cr30Mo2钢焊接接头的组织和力学性能

利用自制的焊接工作台,在ＴＩＧ焊基础上,对Ｃｅ３０Ｍｏ２超纯铁素体不锈施焊。焊接中对焊缝和热影响区附加拖罩和背;衬的Ａｒ气延续保护。对焊接接头质量进行宏观坶检验;借助金相显微镜、扫描电镜（ＳＥＭ）、透射电镜（ＴＥＭ）分析焊缝组织特征一冲击断口形貌;按国家标准测试焊接接头的力学性能。华发头上未发现任何焊接缺陷,焊接缝质量良好;其强度、延性和韧性均达到母材水平,特别是在焊缝和热影响区未出现脆化现象,冲     

2205型双相不锈钢带极电渣堆焊材料的研制

研制出2205型双相不锈钢带极电渣堆焊材料,H2205焊带及其匹配焊剂SJ26B,解决了工程上采用2209型双相不锈钢带极堆焊材料熔敷金属铁素体含量很难达到40％的难题。采用该套材料进行带极电渣堆焊试验,结果表明：堆焊工艺性能极佳,冶金性能优异,熔敷金属力学性能、耐蚀性能优良,熔敷金属铁素体含量为40％-60％,满足工程实际需要。     

Corrosion resistance of laser cladded 304L stainless steel enriched with Ru in hydrochloric acid

The corrosion behaviour of laser surface cladding made from 304L stainless steel alloyed with varying concentrations of ruthenium in 1M HCl at 25°C was evaluated, fresh and after 12 hours, by electrochemical tests including open circuit potential and potentiodynamic polarisation scans. The ruthenium concentration in the 800?µm cladded layer varied from 0.82?wt-% to 4.67?wt-% ruthenium. The ruthenium doped samples were compared against a 304L stainless steel laser surface cladding with no ruthenium, 304L stainless steel samples with no laser cladding, 316L stainless steel, SAF2205 duplex stainless steel and Hastelloy C276®. Initial passivation was not observed in the 1M HCl but after 12 hours the addition of ruthenium led to reduced corrosion rates and improved passivation characteristics compared to the surface cladding without ruthenium. An optimum ruthenium range was observed between 3?wt-% and 5?wt-%. It was shown that at this optimum concentration, the ruthenium containing stainless steel clad on 304L stainless steel can compete commercially with the SAF2205 and Hastelloy C276® as long as the clad is 200?µm or less.     

Effects of Isothermal Ageing and Continuous Cooling after Solubilization in a Duplex Stainless Steel

The kinetics of precipitation of secondary phases in a duplex stainless steel (SAF 2205) after isothermal and continuous cooling treatment were investigated. The evolution of the phases chemical composition in relation with time and cooling rate is presented.     

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.     

Microstructure and Mechanical Properties of Galvanized Steel/AA6061 Joints by Laser Fusion Brazing Welding

Laser fusion brazing welding was proposed.Galvanized steel/AA6061 lapped joint was obtained by laser fusion brazing welding technique using the laser-induced aluminium molten pool spreading and wetting the solid steel surface.Wide joint interface was formed using the rectangular laser beam coupled with the synchronous powder feeding.The result showed that the tiny structure with the composition of a-Al and Al–Si eutectic was formed in the weld close to the Al side.And close to the steel side,a layer of compact Fe–Al–Si intermetallics,including the Al-rich FeAl3,Fe2Al5 phases and Al–Fe–Si s1 phase,was generated with the thickness of about 10–20 lm.Transverse tensile shows the brittlefractured characteristic along to the seam/steel interface with the maximum yield strength of 152.5 MPa due to the existence of hardening phases s1 and Al–Fe intermetallics.     

2219铝合金与不锈钢惯性摩擦焊接接头组织与力学性能

异种金属的连接可实现节能、经济及减重的目标,成为航空航天、造船、铁路运输等领域的研究热点之一;而铝合金与不锈钢物理化学性能差异明显,成为异种金属中最难实现的连接接头之一。采用惯性摩擦焊接技术进行2219铝合金与不锈钢回转体的连接,分析不同焊接工艺参数下铝钢惯性摩擦焊接接头的显微组织与力学性能。结果表明,惯性摩擦焊接使铝钢接头铝合金一侧形成了细晶区和拉长晶区;EDS结果显示焊接界面处发生了Fe、Al等元素扩散。硬度测试结果表明,在连接界面处-0.6~+0.15 mm范围内硬度值发生了明显的阶跃变化,该区域为受焊接热及变形作用的主要区域,硬度值高于母材。合理焊接工艺下获得的2219铝合金与不锈钢接头拉伸强度为235~300 MPa。铝钢惯性摩擦焊接断口以脆性断裂为主。     

低H2S、高CO2分压条件下双相不锈钢应力腐蚀敏感性研究

目的针对IS15156标准中对双相不锈钢使用条件的限制,研究双相不锈钢2205在不同温度、不同低H_2S分压条件下的开裂敏感性。方法通过模拟我国西部酸性油田低H_2S、高CO_2工况环境,利用高温高压设备,进行了三点弯曲试验,结合失重法测试腐蚀速率,并使用SEM和EDS进行微观形貌观察和腐蚀产物分析。结果双相不锈钢2205的腐蚀速率较低,未超过0.014 mm/a,且硫化氢分压对腐蚀的影响较小,但发现了由氧化铝等夹杂导致的点蚀。双相不锈钢2205在低硫化氢分压的中温(100℃)区发生应力腐蚀开裂,同时发生了选择性腐蚀,铁素体相优先于奥氏体相腐蚀,其他温度条件下仅发现点蚀。硫化氢分压升高时,开裂敏感性有一定程度的降低。结论双相不锈钢2205在低硫化氢分压条件下的开裂类型为氢脆型应力腐蚀开裂。氧化物夹杂诱发点蚀,氢在应力集中区域聚集,发生氢脆。当硫化氢分压从6 k Pa增加到165 k Pa时,局部腐蚀敏感性的增加使氢脆得到缓解,开裂敏感性降低。双相不锈钢2205无法在低硫化氢的中温井口环境中使用,标准中以H_2S分压作为使用限制并不十分完善。     

双相不锈钢焊接接头疲劳强度

试验对SAF2205双相不锈钢纵向角接板焊接接头的疲劳强度进行了研究，用有限元计算热点应力集中系数，分别得出了名义应力和热点应力疲劳S-N曲线；用国际焊接学会推荐的方法进行统计处理，并和相同接头形式结构钢的疲劳强度进行了比较。试验表明，双相不锈钢纵向角接板焊接接头名义应力疲劳强度试验结果为FAT136，热点应力疲劳强度试验结果为FAT163，高于相同接头形式结构钢的疲劳级别；双相不锈钢的静载强度级别对其疲劳强度设计级别没有明显的影响。     

2205双相不锈钢的焊接性及焊接技术

对2205双相不锈钢的焊接性能进行了研究分析，对材料的焊接技术关键进行了介绍。