氮对316LN不锈钢拉伸性能的影响

含碳0．02％-0．03％、氮0．06％-0．08％的316LN不锈钢是用于制造快中子增殖反应堆（FBRs）的高温结构部件的首选材料。通过降低碳含量,可大大降低由于焊接而随后在腐蚀性环境出现应力腐蚀破裂的敏感性。FBRs的结构部件的选材所考虑的最重要的力学性能是蠕变、低周疲劳和蠕变疲劳相互作用。用0．06％～0．08％N进行合金化有助于将316L不锈钢的高温强度提高到316不锈钢的水平。     

316LN高氮超低碳奥氏体不锈钢的热变形行为和组织演变

试验的316LN钢（/%:0.011C,0.49Si,1.52Mn,0.016P,0.001S,16.65Cr,13.43Ni,2.18Mo,0.153N）为7.2 t铸锭初轧开坯并锻造成的Φ180 mm圆钢。利用Gleeble-3800热模拟试验机研究了316LN钢在应变速率0.1~50 s^-1、1050~1200℃时的热变形行为和组织演变规律,并通过线性回归分析建立了316LN钢的本构方程。结果表明,变形温度升高有利于动态再结晶的形核,并在热变形过程中促进动态再结晶扩展;热变形过程材料常数α为0.0061,应力指数n为5.5436,表观激活能550.512 kJ/mol,动态再结晶晶粒数量随着变形温度的增加而增多,到1 200℃变形时发生了完全的动态再结晶。     

热加工工艺对316LN奥氏体不锈钢晶粒度的影响研究

采用Zeiss Imager金相显微镜观察316LN奥氏体不锈钢微观组织形貌,研究了变形温度、变形率以及固溶温度对其晶粒度的影响。结果表明,随着变形温度和变形率的增加,显著促进了其动态再结晶的发生,有助于获得细化和均匀化的奥氏体不锈钢晶粒。锻造变形后钢板的晶粒度由小到大依次为表面>1/4处>心部,变形温度和变形量分别为1 050℃,30%时,变形后的晶粒度可达到6级左右。固溶处理对锻造后的钢板晶粒度控制具有均质化作用,结合Jmat-Pro计算分析固溶处理结果,固溶温度应控制在1 020～1 040℃范围内,温度过高容易导致晶粒过度长大,温度过低容易导致Cr2N相析出,影响钢板的塑性和耐蚀性能。     

超级高氮奥氏体不锈钢的耐腐蚀性能及氮的影响

用电化学测试、化学浸泡等方法研究了超级奥氏体不锈钢00Cr24Ni22Mo7Mn3CuN(654SMO)的耐点腐蚀和耐缝隙腐蚀的性能。通过改变氮含量,研究了氮对奥氏体不锈钢的耐点腐蚀和耐缝隙腐蚀性能的影响,结果表明,氮和适量的铬、钼结合,能显提高奥氏体不锈钢的耐点腐蚀和缝隙腐蚀的能力,并且随着氮含量的增国,砥体不锈钢的耐点腐蚀和耐缝隙腐蚀的能力也增强,对比实验表明,超级奥氏体不锈钢在耐点腐蚀,缝隙腐蚀等局部腐蚀性能方面可以和镍基合金C－276媲美,甚至优于镍基合金。     

氮对304奥氏体不锈钢组织和力学性能的影响

在０Ｃｒ１８Ｎｉ９奥氏体不锈钢成分基础上，加入一定的氮，并使钢中的镍含量控制在标准下限含量的条件下，研究了氮对组织和力学性能的影响。结果表明：加氮后钢的强度提高，奥氏体稳定不变，固溶态组织不变，而敏化后晶界析出物类型有所不同。     

316L奥氏体不锈钢的氮合金化

采用金相显微镜、XRD、拉伸试验机及高低温冲击试验机等,并结合Thermo-calc软件计算研究了氮对316L奥氏体不锈钢微观组织、析出相、力学性能和耐点蚀性能的影响.结果表明:氮合金化能够抑制316L不锈钢中σ相和Chi相的析出,增加Cr2N的析出倾向,对奥氏体晶粒细化不明显;氮的添加能够提高316L不锈钢的室温强度和-100℃以上温度的夏比冲击功,降低-100℃以下的夏比冲击功,但对室温拉伸塑性影响不明显.此外,氮能够改善316L不锈钢的耐点蚀能力.     

ITER TF导体铠甲316LN不锈钢管的力学性能

 以ITER TF316LN奥氏体不锈钢无缝管为研究对象,研究了焊接、8%冷变形和650℃、200h的老化处理对316LN不锈钢管性能的影响。分别取母材、焊接接头、经过冷变形和老化处理的焊接接头进行了室温和液氦温度42K下的拉伸和冲击性能的研究,并利用扫描电镜对拉伸和冲击断口的微观形貌进行了观察。结果表明,母材、焊接接头和经过冷变形和老化处理的焊接接头在42K的断后伸长率和冲击韧性依次降低,经过冷变形和老化处理的焊接接头相比母材和未经过任何处理的焊接接头的抗拉强度和屈服强度均高出50~60MPa。42K下,母材的断后伸长率由室温下的48%下降到44%,相反的,焊接接头和经过变形和老化处理的焊接接头的断后伸长率却分别由37%和23%上升到了41%和38%;3种样品在42K下的抗拉强度和屈服强度均是室温下的2~3倍。     

合金元素对316LN不锈钢的力学性能和点蚀性能的影响

研究了N、Cr、Mo和Ni四种合金元素含量的变化对核电主管道用固溶态316LN不锈钢的晶粒尺寸以及常规力学性能和点蚀性能的影响.随着N含量的升高,316LN的晶粒明显细化,其在固溶处理过程中晶粒长大趋势也减小.N含量的升高可改善316LN的力学性能和耐点蚀性能,但是当N质量分数达到0.20%时,其耐点蚀性能又开始变差.晶粒细化对316LN强度的影响远小于N含量对316LN强度的影响.Cr及Ni含量对316LN的晶粒尺寸及抗拉强度、屈服强度等力学性能影响不大;Cr含量增加可轻微改善316LN的抗点蚀能力,Ni元素对316LN的耐点蚀性能影响不大,但可增大钝态的腐蚀速度从而不利于钝化膜的稳定.随Mo含量增加,316LN的晶粒尺寸略有减小,强度增大,延伸率显著降低,耐点蚀能力改善.     

幕墙连接件用铸态中氮奥氏体不锈钢的力学性能和耐蚀性

试验用新型铸态超低碳低镍中氮奥氏体不锈钢022Cr20Mn10Ni6N(%:0.023～0.027C、9.86～9.95Mn、19.24～20.09Cr、5.41～5.42Ni、0.27～0.34N)由15 kg中频感应炉冶炼,并试验研究了铸态022Cr20Mn10Ni6N钢与铸态304钢(%:0.076C、1.87Mn、18.02Cr、8.64Ni)的组织,力学性能和耐蚀性。结果表明,新型铸态不锈钢的力学性能、耐点蚀性能、耐弱酸弱碱均匀腐蚀性能明显优于铸态304不锈钢,新型铸态不锈钢022Cr20Mn10Ni6N中性盐雾耐蚀性和304钢相当,可满足大气环境玻璃幕墙金属连接件的应用要求。     

非真空吹氮工艺对316L奥氏体不锈钢吸氮行为的影响

在实验室通过刚玉坩埚-硅钼棒电阻炉研究了吹氮时间(0～50 min),氮气分压(35～100kPa),吹氮流量(总流量0.3 L/min;N₂:Ar=1:3～3:1),钢液温度(1 773～1 833 K)对0.8 kg 316 L不锈钢液(%:0.031C、16.13Cr、10.12Ni、2.12Mo)中氮含量的影响。结果表明,钢中氮含量随着吹氮时间、氮分压的增加而增大,随吹氮流量增加钢液氮含量达到饱和的时间缩短,氮的溶解度随着钢液温度的降低而升高。应用热力学模型和动力学模型对实验结果进行分析。     

Effect of Surface Mechanical Attrition Treatment on Corrosion Behavior of 316 Stainless Steel

 The nanocrystalline microstructure of the surface of 316 stainless steel (316SS) induced by surface mechanical attrition treatment (SMAT) was determined by X ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of hydrogen embrittlement was first used to obtain the information of the brittleness cleavage plane. The effects of SMAT and the following annealing process on the corrosion behavior of 316SS were investigated by potentiodynamic polarization curves and potentiostatic critical pitting temperature measurements. The results demonstrated that the nanocrystalline layer with an average grain size of 19 nm was produced. However, there were lots of cracks on the surface, which led to the degradation in the corrosion resistance of 316SS after SMAT. Nevertheless, after annealing treatment, the corrosion resistance of the nanocrystalline surface had been improved greatly. The higher the annealing temperature, the better was the corrosion resistance.     

增氮节镍型316奥氏体不锈钢的耐冲蚀性能

采用30 kg真空感应炉熔炼了试验用316钢(/%:0.04C,0.36Si,2.00Mn,0.009P,0.024S,17.74Cr,11.74Ni,2.56Mo)以及采用常压充氮和加入氮化合金熔炼了试验用增氮节镍型316钢(/%:0.04C,0.25Si,1.86Mn,0.012P,0.021S,16.90Cr,8.18Ni,2.64Mo,0.36N),经锻造和轧制成4 mm带材,并经1 100℃1 h固溶处理。借助电子天平、扫描电镜以及自制的砂浆冲蚀磨损试验装置,对试验钢的冲蚀磨损率以及冲蚀磨损后的表面形貌进行了表征与分析。结果表明,两种试验奥氏体不锈钢的磨损率随着冲蚀角度的增大,出现了先上升,后下降,再上升的趋势,在45°与90°出现了两个峰值,当冲蚀角度为90°时,磨损率达到最大值;两种奥氏体不锈钢的冲蚀磨损率随着冲蚀速度和冲蚀时间的增加而增大。在相同的冲蚀条件下,增氮节镍型316奥氏体不锈钢具有较优的耐冲蚀磨损性能和较低的冲蚀磨损率。     

热处理工艺对15-5PH沉淀硬化不锈钢的力学性能与耐蚀性的影响

 研究了热处理工艺对15-5PH沉淀硬化不锈钢力学性能与耐蚀性的影响,并观察了钢中的强化相。结果表明,随着时效温度的升高和保温时间的延长钢的强度逐渐下降,塑性及冲击吸收功逐渐升高,这是由于逆转变奥氏体体积分数随温度升高而增加所造成的;随着时效温度升高钢的耐点腐蚀性能逐渐下降,在580和600 ℃时耐蚀性最差,在480 ℃时效钢的耐点腐蚀性能最佳且具有最高的强度,钢中主要的强化相是具有面心立方结构的富铜相。     

Effect of Nitrogen Content on the Tensile and Stress Corrosion Cracking Behavior of AISI Type 316LN Stainless Steels

This paper deals with the effect of nitrogen on the tensile and stress corrosion cracking (SCC) behavior of type 316LN stainless steel. Yield stress (YS) and ultimate tensile stress (UTS) increased while the ductility [% total elongation (% TE)] decreased with increasing nitrogen content. Evaluation by conventional assessment parameters, such as ratios of UTS, % TE and SCC susceptibility index, derived by SCC testing using the slow strain rate testing (SSRT) technique indicated an improvement in SCC resistance on increasing the nitrogen content. However, crack growth rates, calculated from ratios of fracture stress from the SSRT tests in liquid paraffin and boiling 45 % magnesium chloride in SSRT tests, and the constant load tests at loads corresponding to 20 % YS in boiling 45 % magnesium chloride conclusively established that the SCC resistance of type 316LN stainless steel decreased with increasing nitrogen content.     

Influence of Inclusion and Specimen Orientations on Intergranular Corrosion Testing of AISI 316LN Stainless Steel

Fabricated components must be free from sensitization for using these in critical applications in aggressive environments. During fabrication of a hollow bar from solid bar, deep hole drilling was employed which introduces residual stresses. Stress-relieving heat treatment was employed by heating the hollow bar from room temperature to 1,065°C @ 40°C/h and soaking at 1,065°C for 1 h followed by cooling @ 40°C/h as well as 70°C/h. To detect the susceptibility to IGC, specimens were taken from both circumferential direction as well as longitudinal direction and subjected to ASTM A 262 Practice E test. In U bend, the specimens from the circumferential direction failed whereas longitudinal specimens did not fail. However specimens of both orientations showed Step structure in Practice A test indicating that no carbide has nucleated during the stress-relieving heat treatment ensuring that the cooling rates are faster than the critical cooling rates and the material is not susceptible to IGC. EDAX studies indicated the presence of numerous MnS inclusions enriched in chromium which might have led to chromium depletion around the inclusions resulting in poor passivity at these locations. This study presents the influence of orientation of MnS inclusions in causing failure in U bend test. The need to select specimens of correct orientation during IGC testing is emphasized in this investigation.     

时效处理和氮含量对316L超低碳奥氏体不锈钢冲击韧性的影响

316L超低碳不锈钢(/%:0.010～0.013C、17.50～17.67Cr、10.10～10.60Ni、1.89～2.02Mo、0.020～0.201N)由200 kg真空感应炉冶炼,并经550 mm轧机热轧成15 mm钢板。研究了1 050℃40 min水冷,750℃25～100 h空冷后316L钢的组织和冲击韧性。结果表明,随时效时间增加,316L钢的冲击功下降;同样时效时间,0.201%N的高氮316L钢的冲击功低于0.020%N较低氮316L钢,750℃100 h时效后两者的冲击功分别为40 J和150 J。低氮316L钢主要析出物为碳化物,在晶界和晶内呈细小弥散分布,尺寸为3～5μm;高氮316L钢析出物为100～200μm氮碳化物和σ-相,沿晶界分布。