敏化处理温度对高氮奥氏体不锈钢显微组织和腐蚀性能的影响

利用OM、SEM及Cu-H_2SO_4-CuSO_4腐蚀试验方法、双环电化学动电位活化法和电化学阻抗谱,研究了不同敏化温度对高氮奥氏体不锈钢显微组织特征和晶间腐蚀的影响。结果表明:敏化处理后试样的显微组织为奥氏体,晶界上有析出物;不同敏化温度奥氏体不锈钢的腐蚀敏感性不同,经过相同条件的固溶处理,800℃敏化处理6 h的试样耐腐蚀性能较差,此高氮奥氏体不锈钢晶间腐蚀敏感温度约为800℃。     

固溶处理对高氮奥氏体不锈钢显微组织和腐蚀性能的影响

采用OM观察、SEM观察、电化学动电位再活化法、电化学阻抗分析、动电位极化法等研究了不同固溶处理温度对奥氏体不锈钢组织及腐蚀行为的影响,确定了该高氮奥氏体不锈钢合适的固溶处理温度。采用草酸浸蚀方法和电化学阻抗技术检测不锈钢晶间腐蚀发生和发展过程,初步建立了晶间腐蚀的电化学等效电路,分析了等效电路参数与晶间腐蚀敏感性程度的相关性。     

EPR法评价奥氏体不锈钢晶间腐蚀敏感性的研究

利用电化学动电位再活化（即EPR）法检测了奥氏体不锈钢晶间腐蚀敏感性的程度.研究了不同条件对敏化度的影响,特别是不同敏化时间、敏化温度、扫描速度、溶液温度对奥氏体不锈钢晶间腐蚀性能的影响,并与草酸电解浸蚀实验结果进行对比.结果表明：双环EPR法能定量、定性的检测不锈钢的晶间腐蚀敏感性.对304LNSS而言,敏化时间越长,温度越高,其晶间腐蚀敏感性越强.扫描速度越快,溶液温度越低,同一材料的Ra值越小.EPR法与草酸电解浸蚀试验结果相吻合.     

热处理对低镍铬锰氮奥氏体不锈钢晶间腐蚀的影响

采用交流阻抗谱法和电化学动电位再活化法研究热处理制度对低镍铬锰氮奥氏体不锈钢晶间腐蚀敏感性的影响。结果表明:在550~750℃范围内,晶间腐蚀敏感性随着温度的升高和保温时间的延长而增强。950℃热处理试样无腐蚀倾向。     

应用恒电位浸蚀技术检测奥氏体不锈钢晶间腐蚀敏感性

用恒电位浸蚀方法研究了304L奥氏体不锈钢晶间腐蚀敏感性,并用EPR法对恒电位浸蚀法的实验结果进行验证.研究结果表明,恒电位浸蚀法有可能发展成一种快速检测奥氏体不锈钢晶间腐蚀敏感性的方法     

稳化处理后304H奥氏体不锈钢的晶间腐蚀敏感性分析

研究了304H奥氏体不锈钢稳化处理后的晶间腐蚀敏感性。结果表明,随着稳化处理温度的增加,晶间腐蚀呈现先升高后降低的趋势。稳化处理后的304H奥氏体不锈钢具有良好的耐晶间腐蚀能力。     

用慢应变速率试验方法研究Cr18Mo2铁素体不锈钢的应力腐蚀开裂敏感性

用慢应变速率试验方法在143℃沸腾MgCl_2溶液中研究了不同碳含量、钛的加入量及热处理对Cr18Mo2铁素体不锈钢SCC敏感性的影响。随着碳含量的降低,钢的晶间腐蚀和点腐蚀程度减小,SCC敏感性相应减小。加入适量的钛可以明显减小其SCC敏感性,当Ti/(C+N)比在9.1～13.0时最显著。加入过量的钛引起σ相在晶界附近沉淀,致使SCC敏感性明显增大。 经1100℃处理的Cr18Mo2钢,晶间腐蚀程度显著增大,成为SCC敏感性的控制因素,断口呈沿晶开裂,SCC敏感性明显增大。经850℃处理后,晶间腐蚀明显减轻,点腐蚀成为SCC敏感性的主要的影响因素,断口呈穿晶开裂,SCC敏感性显著减小。 Cr18Mo2钢开裂敏感的应变速率为9×10~(*7)s~(-1)。断裂时间、断裂时延伸率ε_f和断面收缩车RA等参数可适用于评价铁素体不锈钢的SCC敏感性。     

微观组织对2205双相不锈钢氢脆敏感性的影响

采用金相显微镜,氢渗透试验和慢应变速率拉伸试验结合扫描电镜研究了微观组织对2205双相不锈钢氢渗透行为及氢脆敏感性的影响。微观组织分析表明,随着固溶处理温度升高,铁素体含量升高,奥氏体含量降低。氢渗透试验结果显示,随着铁素体含量升高,氢在2205双相不锈钢中的扩散系数增大。结合慢应变速率拉伸试验和断口形貌观察发现,950 ℃固溶处理的2205双相不锈钢的氢脆敏感性较高,呈现脆性断裂;而1050 ℃固溶处理试样中的铁素体和奥氏体含量较均衡,氢脆敏感性较低,呈韧性断裂特征。     

固溶温度对2205双相不锈钢组织和点蚀性能的影响

对2205双相不锈钢热轧板进行了不同温度的固溶处理,采用光学显微镜和扫描电镜分析了不同固溶状态下的组织演变规律,通过FeCl₃溶液浸泡法研究了固溶温度对2205双相不锈钢点蚀性能的影响。结果表明,950 ℃固溶处理后,组织中有s相;经1000~1100 ℃固溶处理后,由奥氏体和铁素体两相组成。随固溶温度升高,铁素体含量逐渐增加,奥氏体晶粒度减小,孔蚀数量、孔蚀平均尺寸和腐蚀速率均呈下降趋势。经1100 ℃×20 min水冷固溶处理后,奥氏体和铁素体含量约各占一半,组织均匀,表现出良好的耐点蚀性能。     

DL-EPR法评价2205双相不锈钢晶间腐蚀敏感性

利用Thermo-Calc软件并结合金相显微镜,定性研究了2205双相不锈钢在800℃下敏化不同时间后的微观组织演变过程.通过研究扫描速率、介质成分、介质温度和试样表面状态优化了双环电化学动电位再活化法(DL-EPR),并用该优化方法研究了2205双相不锈钢晶间腐蚀敏感性.结果表明:DL-EPR法能定量评价σ相对2205双相不锈钢晶间腐蚀敏感性的影响,随敏化时间延长,σ相含量增多,晶间腐蚀敏感性也随之增加.腐蚀形貌的观测验证了这一规律.     

Interkristalline Korrosion ferritischer Chromstähle mit rd. 17 Gew.-% Chrom nach Glühen im Temperaturbereich um 500 °C

Intergranular corrosion of ferritic 17% chromium stainless steels after heat-treatment in the 500 °C temperature range After stabilizing heat-treatment at 750°C, the non-stabilized, ferritic 17% chromium stainless steel Mat.-Nr. 1.4016 (X8Cr17) still contains a sufficient high concentration of carbon dissolved in solid solution, that after heat-treatment in the 500 °C temperature range carbides rich in chromium of the M₂₃C₆-type are precipitated, causing a relatively weak pronounced susceptibility of the steel to intergranular attack. The susceptibility to this type of attack can be detected by testing specimens in the sulfuric acid-copper sulfate-test with increased concentration of sulfuric acid as compared with the DIN standard 50914, followed by metallografic examination of the specimens. The susceptibility to intergranular corrosion of the material investigated occurring after heat-treatment in the low temperature range, which until now is unknown, is described in terms of a Rollason-diagram as it is commonly used for austenitic chromium-nickel stainless steels. As it is to be expected, the stabilized 17% chromium steels Mat. No. 1.4510 (X8CrTi17), 1.4511 (X8CrNb17) and 1.4523 (X8CrMoTi17) are resistant to intergranular corrosion after heat-treatment at low temperatures.     

不同热处理态的304和321奥氏体不锈钢在氯化铵环境中的应力腐蚀行为对比研究

目的 对比研究原始、固溶和敏化态的304和321奥氏体不锈钢在模拟加氢催化氯化铵环境中的应力腐蚀（SCC）行为及机理。方法 将304和321奥氏体不锈钢经过热处理制备成固溶和敏化态试样,采用U形弯试样在模拟加氢催化氯化铵环境中浸泡的应力腐蚀试验方法对其进行研究,通过观察U形弯弧顶的腐蚀形貌和开裂时间,并结合腐蚀及裂纹的SEM照片和电化学测试结果进行分析。结果 原始和固溶状态304不锈钢U形弯试样在氯化铵溶液环境中开裂时间为25 d左右,断口形貌分别为穿晶断口和沿晶断口;敏化态试样18 d后发生开裂,断口形貌为穿晶和沿晶的混合断口。原始和固溶态321不锈钢U形弯试样在该环境中经过39 d均无应力腐蚀裂纹;敏化试样经30 d后产生宏观开裂。电化学测试结果显示,不同热处理态的304不锈钢在氯化铵溶液中均具有明显的点蚀敏感性,321不锈钢在该环境中耐点蚀和应力腐蚀的能力优于304不锈钢。结论 不同状态的304不锈钢在高温氯化铵环境中具有较强的应力腐蚀倾向,特别是敏化态试样;321不锈钢在该环境中的应力腐蚀敏感性相对较小,但敏化处理显著增加了其沿晶应力腐蚀倾向,而固溶态试样具有明显的沿晶腐蚀特征。     

Interkristalline Korrosionsrisse an einem Wellenkompensator aus nichtrostendem Stahl X6CrNiTi1810 bei Korrosionsbelastung durch Heißdampf/Dampfkondensat

Intergranular corrosion cracks of a X6CrNiTi1810 SS expansion bellow stressed in heated steam/steam condensate at elevated temperature Cracking of a single layer corrugated expansion bellow of titanium-stabilized austenitic chromium nickel stainless steel was caused by corrosion fatigue. The crack starts with an intergranular crack path, and the transgranular residual fracture shows striations. Similar manifestations of cracked surfaces of austenitic CrNi steel which were obtained under cyclic loading in MgCl₂ solution are described in the literature. There are, however, corrosion damages by intergranular crack formation in the non-sensitized microstructure of titanium-stabilized ferritic chromium and austenitic chromium-nickel stainless steels in water at elevated temperature, the causes of which have not been elucidated until now.     

节镍型不锈钢的耐腐蚀性能比较

通过3.5%NaCl溶液中动电位极化曲线测定和中性盐雾试验,对200系列奥氏体不锈钢和400系列铁素体不锈钢两类节镍型不锈钢与304不锈钢的耐腐蚀性能进行了对比研究。结果显示,400系列铁素体不锈钢的耐点蚀性能优于200系列奥氏体不锈钢,两种节镍型不锈钢的耐点蚀性能均不如304不锈钢好;200系列奥氏体不锈钢的耐均匀腐蚀性能最差,443不锈钢耐均匀腐蚀性能与304不锈钢相当,439不锈钢比304不锈钢耐均匀腐蚀性能稍差。201、202、304、439和443不锈钢在3.5%NaCl溶液中的点蚀电位分别为(vs.SCE)-32 mV、-22 mV、312mV、165 mV和227 mV,腐蚀速率分别为0.0071 mm/a、0.0062 mm/a、0.0026 mm/a、0.0038 mm/a和0.0024mm/a。     

轨道车辆用不锈钢材料的火焰调修工艺

通过热处理试验研究了火焰调修工艺对S30103-1/8 Hard奥氏体不锈钢的拉伸性能、冲击韧性、硬度、中值疲劳极限以及耐晶间腐蚀性能的影响,回归得到了疲劳寿命曲线,为美标轨道车辆制造提供工艺指导。结果表明:S30103-1/8 Hard奥氏体不锈钢的显微组织为变形奥氏体组织,受热后力学性能容易波动。当火焰调修温度在450~850℃范围内,不锈钢的力学性能、抗晶间腐蚀性能随温度升高呈下降趋势。在调修温度为450℃条件下,增加调修次数对不锈钢板材的抗晶间腐蚀性能和疲劳强度影响不大。因此,选择调修温度不应超过450℃,在此温度下可以进行多次调修。     

New stainless steels for sea-water applications. Part II: Comparison of corrosion and mechanical properties of laboratory and commercial ELI ferritic and superaustenitic stainless steels

This paper represents a follow-up to the first part of the work on new stainless steels for sea-water service. Four laboratory ELI (Extra Low Interstitial) ferritic stainless steels (types 25 Cr-4 Ni-4 Mo), two commercial ELI ferritic stainless steels (types 25 Cr-4 Ni-4 Mo? Ti and 26 Cr-2.5 Ni-3 Mo? Ti) and two highly alloyed austenitic stainless steels (types 20 Cr-25 Ni-4.5 Mo? Cu and 20 Cr-18 Ni-6 Mo? N) have been investigated. With a view to establish the performance of these new alloys in chloride containing environments, systematic electrochemical and laboratory exposure tests have been carried out to define how various factors affect its susceptibility to intergranular, pitting, crevice and stress corrosion. Tension tests were also performed. From the comparison of the localized corrosion resistance and mechanical properties it has been concluded that the laboratory Ti, Ti + Nb or Nb stabilized ELI ferritic stainless steels and the commercial type 25 Cr-4 Ni-4 Mo? Ti of analogous composition could be a valuable alternative to the more expensive highly alloyed stainless steel type 20 Cr-25 Ni-4.5 Mo? Cu which has been especially developed and already used for industrial sea-water applications.     

445铁素体不锈钢内胆水箱的加工性能和耐蚀性

将445铁素体不锈钢的主要化学成分、力学性能、成型性能和焊接性能等基本性能与304奥氏体不锈钢进行对比,结果表明,445不锈钢具有较好的机加工性能。采用盐雾试验及10%的NaCl溶液加速腐蚀试验等方法,对比445水箱、304水箱及两者混合搭配的内胆水箱的太阳能热水器的耐腐蚀性能。结果表明,445不锈钢耐腐蚀性稍逊于304不锈钢,在80～120℃时,445与304不锈钢均发生蒸汽腐蚀、水线腐蚀,且445不锈钢出现较为严重的点蚀现象。     

Effect of nickel alloying on crevice corrosion resistance of stainless steels

The crevice corrosion behaviour of stainless steels containing 25 mass% Cr, 3 mass% Mo and various amounts of Ni was investigated in natural seawater. The results showed that ferritic steels containing nickel were more resistant to corrosion than both ferritic steels without nickel and austenitic steels. The superiority of the Ni bearing ferritic steel over the other steels was in close agreement with the depassivation pH of those steels in acidic chloride solutions. The results showed that the addition of Ni to ferritic steel was effective in decreasing the depassivation pH and the dissolution rate in acidic chloride solutions at crevices.