焊接速度对核级不锈钢焊缝组织和力学性能的影响

利用激光焊接工艺焊接核级不锈钢,通过改变激光焊接速度得到不同的焊接接头,研究了不同焊接速度下焊缝区的组织形貌;通过拉伸试验和冲击试验测试了不同激光焊接速度下焊接接头的力学性能。试验结果表明:随着激光焊接速度的增加,焊缝中铁素体含量逐渐增加;焊接接头强度升高,断后伸长率和冲击韧性先增加后降低;激光焊接接头力学性能优于母材。     

焊接工艺对304不锈钢焊接接头耐晶间腐蚀性能的影响

采用草酸电解侵蚀法和HNO3-HF法研究了焊接电流对304不锈钢焊接接头耐晶间腐蚀性能的影响。研究结果表明:对于填充焊丝308L的焊接接头,耐晶间腐蚀性能随着焊接电流的增大而增强;对于自熔合的焊接接头,耐晶间腐蚀性能随着焊接电流的增大而减弱。     

321和310奥氏体不锈钢焊接接头晶间腐蚀性能对比研究

321和310奥氏体不锈钢分别采用A132和A402焊条焊接,焊后依据GB/T4334-2008《金属和合金的腐蚀-不锈钢晶间腐蚀试验方法》对其焊接接头的晶间腐蚀情况进行了对比分析.研究发现,由于Ti元素的存在,321比310更耐晶间腐蚀.A132焊条中含有Nb元素,使用它焊接会向焊缝金属中过渡合金元素,在一定程度上也可以起到抑制晶间腐蚀的作用.由于焊接过程中受到敏化温度影响,焊缝的耐晶间腐蚀性要比母材差.     

玻璃喷丸处理提高304不锈钢焊接接头抗应力腐蚀性能的研究

基于对304不锈钢焊接试板表面喷丸处理前后的表层残余应力X射线衍射测量，研究了在42％沸腾MgCl2溶液中，表面玻璃喷丸和铸钢喷丸对304不锈钢焊接试板应力腐蚀开裂敏感性的影响，比较了采用不同铸钢喷丸和玻璃喷丸处理工艺的304不锈钢焊接试板抗应力腐蚀开裂的能力．试验结果表明：未喷丸处理的焊接试板6h就发生开裂，50％、100％覆盖率的铸钢喷丸焊接试板分别在试验310h和3500h开裂，而200％覆盖率的铸钢喷丸焊接试板，50％、100％、200％覆盖率的玻璃喷丸焊接试板经历3500h也未见开裂．因此，喷丸处理工艺能够很好地提高焊接构件抗应力腐蚀开裂能力；且在同样喷丸强度下，焊接接头经玻璃喷丸工艺处理后的抗应力腐蚀能力明显优于铸钢喷丸处理工艺．     

核电厂水池结构不锈钢覆面在模拟泄漏环境中的腐蚀性能研究

采用点蚀、晶间腐蚀、电化学和应力腐蚀的方法对核电厂水池结构304L不锈钢覆面在模拟泄漏环境中的腐蚀性能进行研究。结果表明,304L不锈钢在模拟泄漏环境中母材的耐点蚀能力略好于焊缝和热影响区,但比在水池内介质中更易于发生点蚀;在常规硼酸水浓度环境和模拟泄漏环境中304L不锈钢具有良好的抗晶间腐蚀和应力腐蚀能力。     

304L不锈钢真空钎焊接头晶间腐蚀性能试验研究

采用硫酸-硫酸铜法对核级304L不锈钢和BNi-7钎焊料真空钎焊的钎焊接头试样进行晶间腐蚀试验,并使用金相显微镜和扫描电镜对接头组织进行观察和成分分析.结果 表明,不锈钢钎焊接头存在镍基固溶体的选择性腐蚀,镍基固溶体的晶间腐蚀以及母材扩散区的晶间腐蚀三种腐蚀现象,主要原因是钎缝接头内形成的化合物相和Cr优先结合导致周围...     

409L和410L铁素体不锈钢焊接接头力学和腐蚀性能对比

采用TIG自熔焊对409L和410L冷轧板进行了焊接试验,并对焊接接头进行了拉伸、杯突和晶间腐蚀试验,试验结果表明,两种铁素体不锈钢焊接接头的塑性和腐蚀性能存在较大差异,410L焊接接头塑性明显低于409L焊接接头塑性,并且410L焊接接头存在晶间腐蚀敏感性,而409L焊接接头无晶间腐蚀敏感性.在对焊接接头进行硬度测试和金相分析的基础上,讨论了两种铁素体不锈钢焊接接头性能差异的原因,C、N含量和是否Ti稳定化是影响焊接接头性能的关键因素.     

430不锈钢板材显微组织特征及其对腐蚀性能的影响

研究了430不锈钢板材热轧态和950℃退火5 min后的金相组织特征、晶间腐蚀特征以及在酸性腐蚀介质中的浸泡腐蚀特征.结果表明,热轧态在酸性腐蚀介质中有较明显的分层腐蚀现象,而退火态则为均匀腐蚀.热轧态在0.5 mol/L H2SO4+ 0.01 mol/L KSCN溶液中有明显的晶间腐蚀倾向,而退火态晶间腐蚀现象消除.综合分析表明:实验用钢的腐蚀特征由碳化物条带所致.     

改性纳米SiC粉体对铸造304不锈钢腐蚀性能的研究

在生产条件下采用冲入法制备了改性纳米SiC粉体强化铸造304不锈钢.利用静态浸泡试验、电化学分析法研究了改性纳米SiC粉体对304不锈钢点腐蚀和晶间腐蚀性能的影响.结果表明:经改性纳米SiC粉体强化处理后的304不锈钢耐腐蚀性得到有效提高;添加纳米SiC粉体的304不锈钢在强酸条件下表现出优越的抗晶间腐蚀性能;添加纳米SiC粉体的304不锈钢的电极-电位提高了68 mV、自腐蚀电流减小0.122 mA、腐蚀速率降低了90.12％.     

热输入对不锈钢激光搭接焊接头晶间腐蚀敏感性的影响

利用双环电化学动电位再活化法研究了激光焊接热输入对奥氏体不锈钢激光搭接焊接头晶间腐蚀敏感性的影响,并通过X-射线衍射仪、扫描电子显微镜及能谱仪分析了激光搭接焊接头的相组成与主要合金成分. 结果表明,不锈钢激光搭接焊接头的晶间腐蚀敏感性高于母材,且随着激光热输入的增加,焊接接头的阳极极化曲线钝化区间逐渐变窄,维钝电流密度增大,再活化率Ra = Ir/Ia增大,接头的晶间腐蚀敏感性增加. 与焊缝金属相比,焊接热影响区的晶间腐蚀倾向更为明显,成为接头中耐晶间腐蚀性能最薄弱的部位,而在晶界上析出M₂₃C₆导致晶界贫铬是晶间腐蚀敏感性增加的主要原因.     

Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 °C for 30 min to 10 h. The heat-treated samples then undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr₂₃C₆ precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 °C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted.     

Influence of microstructure on the corrosion resistance of hyperduplex stainless steel

Hyperduplex UNS S32707 is a newly developed austenitic–ferritic stainless steel. The steel contains about 27%Cr, 7%Ni, 4.5%Mo, and 0.4%N, which results in a pitting resistance equivalent factor (PRE) equal to 49. In this study, the pitting corrosion resistance of this new grade of stainless steel was investigated by varying the microstructure using different thermal processes. The critical pitting temperature measurement and cyclic polarization tests confirm the high corrosion resistance of the hyperduplex steel in the solution treated condition. However, deleterious phases form easily during thermal processing and cause a drastic decrease in the corrosion resistance.     

焊接速度对18-8不锈钢堆焊层组织形态的影响

采用带极电渣焊方法在Q235表面得到了18-8不锈钢堆焊层。研究不同焊接速度对18-8不锈钢堆焊层组织形态的影响。结果表明,带极电渣堆焊层显微组织主要由奥氏体和少量δ铁素体构成,其中δ铁素体有断续状(或称蠕虫状)、骨架状和板条状三种形态,决定于堆焊层的合金成分、焊接热输入及冷却条件等因素。当焊速过小时,堆焊层组织中δ铁素体的形态主要是断续状和骨架状;当焊速过大时,δ铁素体的形态主要是板条状和骨架状;当焊速适中时,可获得热输入小、稀释率低、成形良好,显微组织为奥氏体基体和骨架状δ铁素体的堆焊层组织。     

A304不锈钢薄板激光焊接接头微观组织及电化学腐蚀研究

为了研究A304不锈钢薄板的连续激光焊接工艺及电化学腐蚀性能,本文采用英国GSI公司的JK2003SM型Nd：YAG固体激光器进行焊接实验,并对焊接接头微观组织进行了研究。研究结果表明工艺参数为P=1 600 W,v=3 mm/s,焊后熔宽为1.6 mm,焊缝的中心位置有等轴晶;A304不锈钢焊接接头耐蚀性最强的是焊缝金属区、其次是母材区、最弱的是热影响区。     

FCAW repair welding cycles,HAZ microstructure and corrosion resistance of 2304 duplex stainless steel

Flux-cored arc welding (FCAW) is an automatic welding process widely employed to join duplex stainless steel (DSS) structures in industrial plants because of its high productivity. However, when multiple passes are performed, this process can lead to the formation of non-metallic inclusions originating from the slag in the fusion zone. In this case, the welded joint can be repaired using the same welding process. Some regions next to the heat-affected zone are not removed during the repairing operation. Thus, these regions are subjected to repeated welding cycles and to a high heat input, which can cause microstructural alteration that impairs the corrosion resistance of the welded material. The aim of this work was to study the corrosion resistance of 2304 DSS plates joined using the FCAW process and repaired using the same process. The influence of the repair procedure on the corrosion resistance of the welded joints was evaluated using potentiodynamic polarisation and chronoamperometric curves, which allow the determination of the critical pitting temperature of the samples. The microstructure obtained after each repair cycle was evaluated using optical microscopy and scanning electron microscopy. The results showed that the corrosion resistance was depressed as the number of repair cycles increased.     

Accessing the full spectrum of corrosion behaviour of tempered type 420 stainless steel

Bipolar electrochemistry produces a linear potential gradient between two feeder electrodes, providing access to the full spectrum of anodic-to-cathodic electrochemical behaviour. A type 420 martensitic stainless steel has been used to investigate microstructure evolution and corrosion behaviour with application of different tempering heat treatments. Tempering treatments at 250°C, 400°C and 700°C revealed the occurrence of pitting corrosion, with treatments at 550°C resulting in general and intergranular corrosion. Cr₂₃C₆ was present in all tempering conditions, with Cr₇C₃ and CrC only observed for tempering at 550°C. The 250°C tempering treatment had the highest corrosion resistance with a hardness value much higher than 500 HV.     

经济型铁素体不锈钢焊接接头组织与耐蚀性能

采用ER-309焊丝焊接了TCS345,T4003,Nirosta 4003,JFE410RW四种铁素体不锈钢,用金相方法分析了四种母材、接头的显微组织,通过电化学极化曲线测量,对母材和焊接接头的耐腐蚀性能进行了评价.结果表明,TCS345和T4003铁素体不锈钢与Nirosta 4003和JFE410RW铁素体不锈钢的主要区别是钛和锰含量偏低,尤其是钛含量少,导致TCS345和T4003铁素体不锈钢的晶粒长大倾向较Nirosta 4003和JFE410RW铁素体不锈钢的明显.铁素体不锈钢焊接接头存在较大的热影响区,热影响区的组织与母材晶粒相比,其晶粒明显粗大;TCS345铁素体不锈钢的晶粒长大严重,Nirosta 4003和JFE410RW铁素体不锈钢的铁素体晶粒尺寸比TCS345略小,晶粒长大不明显.在1mol/L Na2SO4溶液中,TCS345和JFE410RW不锈钢母材的腐蚀性能优于T4003和Nirosta 4003.     

焊接及热处理工艺对0Cr18Ni9Ti不锈钢耐蚀性的影响

通过草酸电解结合组织观察、动电位扫描法和交流阻抗测试研究了直流焊、脉冲焊和固溶处理、稳定化处理对0Cr18Ni9Ti不锈钢的抗晶间腐蚀性和耐点蚀性的影响.结果表明,脉冲焊比直流焊对晶间腐蚀的不利影响更大;固溶处理可以明显改善焊后材料的耐晶间腐蚀以及耐点蚀性,并增大钝化膜的稳定性.