固溶温度对超级双相不锈铸钢在海水中耐蚀性的影响

通过测量阳极极化曲线研究了固溶处理温度对超级双相不锈铸钢在人工海水中腐蚀的影响.结果表明:经不同温度固溶处理的超级双相不锈铸钢材料在人工海水中自腐蚀电位相差不大,均具有钝化性能,维钝电流密度为0.1 mA/cm2 左右;室温海水中,不同温度的固溶处理对腐蚀电流密度影响也不大;海水温度由室温升至80℃,钝化区宽度急剧变窄...     

2205双相不锈钢的织构对冲击韧度的影响

对2205双相不锈钢进行不同温度的固溶处理试验和改锻试验。研究了试验钢-46℃的冲击吸收能量,冲击试样断口的宏观形貌及纵截面和横截面的显微组织。结果表明,未经改锻的试验钢由于无明显的锻造织构,冲击试样断口基本是结晶状断口,经1050℃、1100℃和1150℃保温1 h固溶处理后冲击吸收能量均为20 J左右;试验钢改锻后,形成明显的锻造织构,冲击吸收能量提高到70 J,再经1050℃保温1 h固溶处理后冲击断口有明显纤维区,冲击吸收能量进一步升高到150 J。     

Effect of Preaging Deformation on Aging Characteristics of 2507 Super Duplex Stainless Steel

In the present study, precipitation of sigma (σ) phase was investigated over the temperature range of 700-850 °C in undeformed and deformed (60% cold rolling) samples of 2507 super duplex stainless steel. The fraction of sigma phase formed as a result of the transformation α → σ + γ₂ increases with increasing time and temperature. The increase in sigma phase leads to increase in yield strength and decrease in ductility. Preaging deformation leads to accelerated precipitation of sigma phase. The activation energy for sigma phase precipitation in deformed sample is found to be lower than that in undeformed sample.     

热处理工艺对2205双相不锈钢耐蚀性能的影响

对2205双相不锈钢采用不同温度进行热处理,然后用光学显微镜和电子扫描电镜观察其在0.33mol/L FeCl3+0.05 mol/L HCl溶液中腐蚀后的形貌;测试其显微硬度的变化、在沸腾的65%的硝酸溶液中浸蚀24 h的腐蚀速率和在25℃的3.5%NaCl溶液中的点蚀电位。研究表明:2205双相不锈钢在750~900℃保温4h有σ相析出,材料的显微硬度增大。同时随着热处理温度的升高,2205双相不锈钢的点蚀电位降低,腐蚀速率增大。     

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。     

Effect of the Heat Treatment on the Corrosion Resistance of Duplex Stainless Steels

Duplex stainless steels (DSS) are biphasic austenitic-ferritic steels in which the best combination of mechanical and corrosion resistance properties is achieved for an almost equal volume fraction of the phases. In this work, the effect of secondary phases precipitation on the corrosion resistance of four DSS grades (2101, 2304, 2205 and 2507), after isothermal aging in the critical temperature range 750-900 °C, was studied. The corrosion resistance was investigated by potentiodynamic polarization tests in both 0.6 M NaCl solution (pH 7) and in an acid chlorinated solution (pH 3) at room temperature. Moreover, the critical pitting temperature was determined according to ASTM G150. The results showed that secondary phases precipitation mainly influenced the resistance to corrosion of the lean duplex grades.     

Change of Precipitation Behavior and Impact Toughness with Depths in Quenched Thick SAF 2507 Super Duplex Stainless Steel

We investigated the change of precipitation behavior and impact resistance as a function of depth from the surface of thick block of SAF 2507 super duplex stainless steel with the thickness (T) of 200 mm after water quenching from 1050 °C. The amount of detrimental sigma phase increased smoothly until the depth of 0.25T, followed by a rapid increase from 0.25T to the center. However, the impact strength decreased significantly with only 1.3% of area fraction of sigma phase as the depth increased past 0.1T. Based on fractography analysis for the samples at such small depth ranges, the distance between the sigma phase particles affected the relative amount of initiating brittle cracks in front of the notch and was one of the crucial factors that dramatically reduced impact resistance with depth.     

2205双相不锈钢在硫酸中的腐蚀性能

采用腐蚀浸泡失重方法结合动电位极化曲线和电化学阻抗谱,研究了不同温度下2205双相不锈钢在不同浓度H2SO4溶液中的耐蚀性,并与传统的20R钢和316L不锈钢作对比。结果表明,三种材质的耐蚀能力由强到弱排序为:2205316L20R;硫酸浓度和温度对腐蚀速率的影响由强到弱排序都为:20R316L2205。在T≤40℃,2205双相不锈钢的腐蚀深度为0mm/a,耐蚀性等级为1级,评定为完全耐蚀;当温度增加至60℃且硫酸浓度为30%时,其腐蚀速率显著增加,腐蚀深度为27.026mm/a,耐蚀性等级为10级,评定为不耐蚀。高铬含量可以降低不锈钢材料的钝化电位,另一方面可以增强不锈钢表面钝化膜的修复能力,可能是2205双相不锈钢比316L和20R更耐蚀的本质原因。     

超级双相不锈钢叶轮的研制

基于双相不锈钢的铸造特性,设计了电站循环水泵用超级双相不锈钢叶轮铸件的铸造工艺,并确定了其熔炼、浇注、开箱、热处理、焊补等主要工序的生产控制要点。试生产结果表明,所生产的超级双相不锈钢叶轮铸件产品完全满足质量和技术要求。     

热老化对铸造双相不锈钢显微组织的影响

用光学金相(OM)和透射电镜(TEM)等分析方法,研究了法国产Z3CN20-09Mα+γ铸造双相不锈钢(CSS)在400 ℃加速老化试验后显微组织的变化,探讨热老化对显微组织的影响.结果表明,Z3CN20-09Mα+γ铸造双相不锈钢组织为奥氏体基体上分布着不连续的岛状铁素体,主要形态为条带状和花边状.随老化时间的延长,在局部区域铁素体的形态由不连续的岛状和花边状变为尖锐的长条.奥氏体内的位错、层错也有明显的减少,在晶界处有析出物、位错上有沉淀物的出现.     

热老化对铸造双相不锈钢管道亚结构的影响

对核电站压水堆一回路用Z3CN20-09M铸造双相不锈钢进行400℃恒温加速热老化试验,持续加热时间分别为1000h和3000h,利用透射电镜(TEM)分析其在不同热老化时间下亚结构的变化,以及热老化过程对亚结构的影响。结果显示,热老化过程中显微组织形态无明显变化,为奥氏体基体上分布着不连续的岛状铁素体,但亚结构发生了明显改变。奥氏体基体在热老化初期有大量位错缠结及高密度的层错,随热老化时间的延长,基体中的位错缠结程度明显减轻,层错数量大大减少,在位错、相界及晶界上有析出物出现,铁素体相内出现调幅分解。     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

热处理工艺对430铁素体不锈钢耐蚀性的影响

将真空感应熔炼得到的试验钢进行固溶处理和稳定化处理,通过金相、扫描电镜、能谱、显微硬度及电化学方法,研究了热处理工艺对430铁素体不锈钢组织和耐蚀性能的影响。结果表明,通过1 050℃保温1h水冷后得到的试验钢的耐蚀性最好,通过分析可以发现,通过固溶处理能得到过饱和固溶体,减少碳化铬的析出,呈现较为均匀的显微组织,从而改进试验钢的耐蚀性能。     

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。     

两种热处理工艺对2205双相不锈钢腐蚀行为的影响

采用动电位极化曲线、显微形貌观察的方法研究了两种热处理工艺对2205不锈钢在高Cl-环境中的腐蚀行为。通过金相组织分析观察热处理后样品的组织形貌,在此基础上建立了显微组织与腐蚀行为之间的相关性。结果表明,950℃热处理+炉冷处理导致2205双相不锈钢中σ相大量析出,造成σ相周围铬和钼含量的减少,从而使双相不锈钢的耐腐蚀性能显著降低。     

Investigation on Microstructure and Impact Toughness of Different Zones in Duplex Stainless Steel Welding Joint

This paper investigated on microstructure and impact toughness of different zones in duplex stainless steel welding joint. High-temperature heat-affected zone (HTHAZ) contained coarse ferrite grains and secondary precipitates such as secondary austenite, Cr₂N, and sigma. Intergranular secondary austenite was prone to precipitation in low-temperature heat-affected zone (LTHAZ). Both in weld metal (WM) and in HTHAZ, the austenite consisted of different primary and secondary austenite. The ferrite grains in base metal (BM) presented typical rolling texture, while the austenite grains showed random orientation. Both in the HTHAZ and in the LTHAZ, the ferrite grains maintained same texture as the ferrite in the BM. The secondary austenite had higher Ni but lower Cr and Mo than the primary austenite. Furthermore, the WM exhibited the highest toughness because of sufficient ductile austenite and unapparent ferrite texture. The HTHAZ had the lowest toughness because of insufficient austenite formation in addition to brittle sigma and Cr₂N precipitation. The LTHAZ toughness was higher than the BM due to secondary austenite precipitation. In addition, the WM fracture was dominated by the dimple, while the cleavage was main fracture mode of the HTHAZ. Both BM and LTHAZ exhibited a mixed fracture mode of the dimple and quasi-cleavage.     

Effect of Heat Treatment on Corrosion Behavior of Duplex Stainless Steel 2507 in Artificial Saliva

Metal Science and Heat Treatment - The effect of heat treatment of duplex stainless steel 2507 on its corrosion in artificial saliva is studied. The microstructure of the steel is analyzed using...     

2205双相不锈钢模拟焊接HAZ组织与性能

采用热模拟法研究了2205DSS焊接HAZ的组织与性能，探讨了冷却时间对模拟HAZ冲击韧性的影响规律。结果表明：冷却时间对组织及性能有很大的影响，随冷却时间的延长，铁素体含量减少，奥氏体含量增加，冲击韧性增大：随冷却时间延长，模拟组织显微硬度降低，而且模拟组织中铁素体的硬度低于奥氏体的硬度：固定冷却时间t8／5时，随冷却时间t12／8的增加，冲击韧性提高：固定冷却时间t12／8时，随冷却时间t8／5的增加，冲击韧性降低。     

2205双相不锈钢管材的断裂韧性分析

某天然气集输管道最高工作压力13.3MPa,最低工作温度-30℃,对材料的韧性提出了较高的要求.本文对该高压天然气管道用2205双相不锈钢管材进行了夏比V形缺口冲击试验、落锤撕裂试验(DWTT)和裂纹尖端张开位移(CTOD)试验,对该材料的断裂韧性特征进行了研究.结果表明,2205双相不锈钢材料具有较高的夏比冲击吸收功,较低的韧脆转变温度(FATT)和较高的CTOD值,表明该材料具有良好的断裂韧性,用于高压输气管道具有较高的安全性.     

固溶处理对低镍双相不锈钢耐点蚀及强韧性能的影响

采用“C/N+Mn代Ni”的合金设计方法,制备出了一种具有良好热加工性能的低镍双相不锈钢21Cr-DSS,并研究了固溶处理工艺对新钢种微观组织、强韧性及耐点蚀性能的影响。结果表明:21Cr-DSS在热轧过程中铁素体比奥氏体更容易发生动态软化。固溶温度比保温时间对21Cr-DSS中两相比例的影响更明显,且奥氏体晶粒尺寸稳定性优于铁素体。随固溶温度升高,21Cr-DSS的强韧性得到改善,但当温度超过1100℃后,强韧性下降。在1050℃固溶处理30 min时,21Cr-DSS具有最佳的综合性能,此时强塑积为58.9 GPa%,-40℃低温冲击功为84 J,在3.5%氯化钠溶液中的点蚀电位为0.43V。21Cr-DSS比常规LDX2101具有更优异的热加工性能和强韧性,且耐点蚀性能基本相当。与AISI 304奥氏体不锈钢相比,21Cr-DSS的强度和耐点蚀性能明显更优。