低碳钢及焊缝硝酸盐露点腐蚀开裂研究

用U形恒应变实验方法，研究了20 g、16MnR、Q235-A 材及焊接材料浸泡在不同浓度硝酸铵溶液中的开裂敏感性，同时也讨论了硫的氧化物对硝酸盐露点腐蚀开裂敏感性的影响.结果表明：焊接材料比基材更易于发生硝酸盐露点腐蚀开裂，20 g比16MnR、Q235-A在硝酸盐中有更低的开裂敏感性，硫的氧化物增加了开裂敏感性.在此基础上，还探讨了硝酸盐露点腐蚀开裂的类型和机理.     

激光冲击处理对X70管线钢焊接接头H_2S应力腐蚀影响

采用慢应变速率法(SSRT)进行了X70管线钢焊接接头在H2S介质中应力腐蚀试验,研究了H2S对X70管线钢焊接接头应力腐蚀开裂(SSCC)的敏感性,分析了激光冲击处理对X70管线钢焊接接头抗H2S应力腐蚀开裂SSCC行为的影响。结果表明,经激光冲击处理后X70管线钢焊接接头表面产生了晶粒细化和残余压应力,提高了管线钢焊接接头在NACE饱和H_2S溶液中抗应力腐蚀性能;原始状态试样在NACE饱和H_2S溶液中慢拉伸试验平均应力腐蚀敏感性指数>25%,有明显的应力腐蚀倾向;经激光冲击处理后试样在NACE饱和H_2S溶液中平均应力腐蚀敏感性指数为19.05%,应力腐蚀倾向不明显,因此,激光冲击处理有效地提高了X70管线钢焊接接头的抗应力腐蚀性能。     

CeO2改性渗铝层在H2S溶液中的耐腐蚀性能

采用在碳钢表面复合沉积Ni—CeO2扩散渗铝的方法，得到了CeO2改性的复合渗层，在H2S溶液腐蚀条件下对渗层进行了耐腐蚀性能试验研究，并利用SEM对渗铝层的显微组织进行了分析。结果表明，经CeO2改性渗铝的方法获得了富集CeO2的细晶层，同时，渗层的耐H2S腐蚀性能明显提高，腐蚀质量增量为纯铝渗层的40％。     

16Mn(HIC)钢在硫化氢环境中的应力腐蚀开裂行为

用慢应变速率拉伸实验及U形弯试样浸泡实验研究了16Mn钢和16Mn(HIC)钢的基体及焊缝材料在酸性H2S溶液中的应力腐蚀开裂(SCC)行为.结果表明:在实验条件下上述材料均具有明显的SCC敏感性,其裂纹是氢致开裂引起的穿晶型应力腐蚀开裂;16Mn(HIC)钢抗SCC的性能优于16Mn钢,但16Mn(HIC)不具有明显的耐SCC的性能;两种材料焊缝的SCC敏感性明显大于母材,热处理能够改善焊缝抗应力腐蚀开裂的性能.     

H2S环境下碳钢连续油管的SSC行为研究

连续油管井下作业技术已经成功地广泛应用于非酸性环境,向酸性环境下的推广应用中,由于酸性环境含有H2S,碳钢连续油管面临H2S导致的损伤,特别是硫化物应力腐蚀开裂(SSCC)。本工作以38.1mm×3.18mm规格的CT80碳钢连续油管为研究对象,采用应力环加载和四点弯曲加载对连续油管进行了SSC试验研究,并针对通过SSC试验的试样开展拉伸试验和弯曲试验,对比分析材料在遭遇H2S环境后的性能变化。试验结果显示,连续油管遭遇H2S环境后,由于H2S导致的损伤,拉伸性能和弯曲性能都会下降。加载应力越大、接触H2S介质时间越长,材料的性能下降越明显。应力环加载与四点弯曲加载相比,采用应力环加载进行SSC试验,其结果表明SSC敏感程度更严重。     

焊缝为镍基合金的管线钢焊接接头SSCC行为研究

研究了焊接材料为ARC625,焊缝为镍基合金的管线钢焊接接头的H2S应力腐蚀(SSCC)性能,与焊缝为普通碳钢的管线钢焊接接头的SSCC性能做了比较。SSCC试验结果表明,两种接头均出现了开裂现象,断口形貌为准解理断裂,进一步分析发现焊缝为镍基合金的接头组织较均匀,而焊缝为普通碳钢的接头开裂区域存在大量马氏体/奥氏体,碳化物呈连续状分布。与母材相比,硬度值在两种焊接接头的热影响区区域急剧增加,镍基合金焊缝硬度超过了管线钢硬度极限值,而热影响区硬度接近该值。极化曲线测试结果显示,焊缝为镍基合金的接头热影响区腐蚀电流密度及腐蚀速率均小于第2种接头的热影响区以及母材区域,焊缝为镍基合金焊接接头表现出了更加优异的电化学腐蚀性能。     

激光冲击对X70管线钢焊接接头H_2S应力腐蚀断口的影响

利用激光冲击波对X70管线钢焊接接头进行了改性处理,通过慢应变速率法（SSRT）研究了其在NACE（national association of corrosion engineers）标准饱和H2S溶液中应力腐蚀的敏感性,并对其断口进行SEM观察,分析了激光冲击处理对X70管线钢焊接接头抗H2S应力腐蚀开裂（SCC...     

X65级海管环缝无衬垫封底全自动焊工艺及焊缝性能研究

在一些国外海洋油气田开发项目中，输送含有酸性腐蚀介质的海底管道环缝焊接强制要求采用无铜衬垫封底焊接技术，确保焊缝在硫化氢（Hydrogen Sulfide,H2S）酸性腐蚀服役过程中不会出现硫致应力开裂（Sulfide Stress crack,SSC）。为解决铜衬垫在封底焊接过程中铜原子受热扩散进入焊缝金属并对其性能产生破坏性影响的问题，采用表面张力过渡（Surface Tension Transfer,STT）封底焊接和熔化极气体保护焊接（Gas Metal Arc Welding,GMAW）填充盖面焊接技术，开发了一种适用于海管S型铺设的无衬垫封底全自动焊工艺并对焊缝性能进行测试研究。结果表明，横向拉伸、全焊缝拉伸、侧弯、冲击、宏观硬度及H2S腐蚀试验等均满足项目焊接规格书及DNV OS F101(2013)标准要求；焊接接头试样均通过了NACE 0177标准下的硫致应力开裂试验，可应用于含H2S酸性环境下X65级碳钢海管的焊接施工。STT表面张力过渡封底焊接属于单面焊双面成形技术，焊接热输入小，飞溅极少，焊缝成形好，是无衬垫封底焊接技术的一种可靠选择。     

渗铝钢管的焊接方法

渗铝钢的焊接一直是国内外尚未解决的难题,阻碍着渗铝钢的推广使用。详细分析了碳钢渗铝后焊接存在的问题,提出了新的渗铝钢管焊接方法,使其焊缝区的性能基本上与渗铝钢母材性能相当。当钢管壁厚∧12mm时,宜采用钎焊法焊接;当钢管壁厚≥12mm时,宜采用堆焊法焊接。     

国产X80管线钢的H2S应力腐蚀开裂行为

采用三点弯曲加载法,研究了国产X80管线钢及其焊接接头的抗H2S环境应力腐蚀开裂（SSCC）行为.结果表明,热影响区（HAZ）对应力腐蚀开裂最为敏感,主要是HAZ组织不均匀、晶粒粗大、硬度大,易引起局部腐蚀,从而导致该区SSCC敏感性高。母材的纵向和横向取样对H2S应力腐蚀不敏感,薄壁管材较厚壁管材有更好的H2S环境应力腐蚀抗力.      

16MnR 钢在催化裂化再生环境中的应力腐蚀裂研究简

通过U形试样应力腐蚀实验、电化学极化曲线等方法,在模拟催化裂化再生器环境条件下,研究了HNO3-H2SO4-H2O体系中16MnR钢及其焊缝的应力腐蚀行为。结果表明:16MnR钢焊接接头在不同实验条件下均比基材更易产生硝酸盐应力腐蚀开裂,其机理主要是阳极溶解;引入硫酸根和降低pH值均能破坏16MnR钢的保护膜,增大其焊接接头的应力腐蚀敏感性;当溶液的pH值降低至2以下时,材料处于活化状态,发生严重的均匀腐蚀。     

Einfluß der Oberflächenbeschaffenheit auf die Beständigkeit nichtrostender,austenitischer Chrom-Nickel-Stähle gegen transkristalline Spannungsrißkorrosion

Influence of surface conditions on the resistance of stainless austenitic bromium nickel steels to transcrystalline stress corrosion Grinding weld seams may result in an increased susceptibility to stress corrosion cracking of the areas treated in that way. This susceptibility may be eliminated by an ultimate pickling step; the thickness of the layer to be removed is 0.15 to 100 μm, depending on surface roughness. The susceptibility to stress corrosion cracking of the ground zones can be determined, however, only in the boiling 42% MgCl₂-solution; no stress corrosion cracking could be produced in solutions containing from 10 to 3O% MgCl₂ or 10 to 2O% and even 40% CaCl₂. Another possibility to eliminate stress corrosion cracking susceptibility is an ultimate sand blasting which produces compressive residual stresses in the ground surface.     

Korrosionseinflüsse auf Schweißverbindungen

Corrosion effects on welds The author stresses the pecularities of the weld zone as compared to the properties of the base material and shows the impact of these pecularities on susceptibility to intercrystalline corrosion, stress corrosion cracking, crevice corrosion fatigue. On the basis of comprehensive data from literature weld ability and problems related therewith are discussed with reference to the following material: unalloyed and low alloy steels, stainless steels (ferritic and austenitic), Al and its alloys, Ti, Zr and Ta. Finally the influence of galvanizing on the weldability of constructional steels is discussed and the importance of design is pointed out.     

Allgemeine Beständigkeit von Schweißnähten unter Berücksichtigung der Spannungs- und Schwingungsrißkorrosion

General resistance of weld seams with a view to stress corrosion cracking and corrosion fatigue The corrosion of welds is due to thermal effects during welding which give rise to structural changes and, frequently, compositional changes in the transition zone. The welded material is rapidly cooled and may thus be heterogeneous and may present residual stresses resulting in increased susceptibility to selective and stress corrosion. The manganese content is of high importance in low alloy steels, as well as residual martensite or austenite embedded in a ferrite matrix. Low ferrite contents are generally beneficial because they counteract high temperature cracking; however, ferrite contents should be hept below 10% in order to prevent the formation of a continuous network giving rise to selective corrosion. Corrosion susceptibility may also be produced by carbide or carbonitride precipitation in austenitic and ferritic steels and nickel base alloys. Weld zones in aluminium alloys are attacked in rare cases (e.g. by HNO₃) and the susceptibility of Ta, Zr and Ti depends from the properties of the protective atmospheres.     

Stromdichte-Spannung-Messungen an nichtrostenden Stählen in aktivierenden Medien

Current density-potential measurements on stainless steels in active media In order to elucidate the susceptibility to selective corrosion of weld seams in stainless steels potentio-kinetic current density-potential measurements have been made. When the polarisation curve for the weld seam is more anodic in the vicinity of the rest potential than the curve corresponding to the base material the weld seam is selectively attacked; when, however, the weld seam is moer cathodic than the base metal there is almost no corrosion in the adjacent areas because of the large area ratio (large anode, small cathode). It is only in extreme cases (very high potential difference between cathodic weld seam and anodic plate) that local corrosion is found in the base metal. Tests with Hastelloy B in 20% hydrochloric acid show that this material cannot be welded successfully with identical material; it might, however, be feasible to weld it with cathodically alloyed weld fillers (alloyed with Pt or Pd).     

16MnR钢在含H2S介质中的慢应变速率腐蚀试验研究

通过慢应变速率法(SSRT)应力腐蚀试验,研究了16MnR钢的H2S应力腐蚀敏感性,修正了计算应力腐蚀敏感性指数的方程.结果表明,水溶液中pH值对16MnR钢的应力腐蚀影响较大,16MnR钢的应力腐蚀敏感性H2S浓度应该根据pH值确定.     

Untersuchungen zur Spannungsrißkorrosionsbeständigkeit nichtrostender Stähle mit unterschiedlichem Verformungsgrad

Investigations on stress corrosion cracking resistivity of stainless steels with different degree of cold straining Within the context of the elaboration of a new approval for stainless steels for civil engineering applications the question arised whether cold straining could adversely affect the resistance against stress corrosion cracking. By means of experimental tests with different stainless steels it should be clarified whether cold straining increase the stress corrosion cracking susceptibility under high chloride loads like e.g. in swimming hall atmospheres. The investigations were carried out using the high-alloyed steels 1.4462 and 1.4529. As reference material with known susceptibility against stress corrosion cracking the steel 1.4301 was used. The tests were performed using U-bent and tension specimens with saturated MgCl₂ salt spots. Indications for an increase in stress corrosion cracking susceptibility of the cold drawn steel were not found.     

CERT (Constant Extension Rate Testing) als Spannungsrißkorrosionsprüfmethode für Schweißverbindungen. I. Mechanisch-chemische Untersuchungsergebnisse

CERT (Constant Extension Rate Testing) as a test method for stress corrosion cracking at weld joints. I. Mechano-chemical test results Investigations by means of CERT on the corrosion system structural steel/nitrate solution have been performed with special consideration of the influence of weld joints on stress corrosion cracking (SCC) susceptibility. Specimen with real weld joints and specimen with simulated weld joint structures (base material, course grain region, fine grain region) have been used. Results expressed as relative fracture energy show a significant influence of the heat affected zone of the simulated weld joints but not at the real weld joints. As expected, the SCC resistance decreases in the sequence of the steels 15 Mo 3 - StE 355 - H II. All experiments exhibit increasing SCC resistance with increasing heat input. Part II of this work contains metallographic results and discussion of the applicability of CERT for weld joints.     

Inter- und transkristalline Spannungsrißkorrosion austenitischer Mn- und CrNi-Stähle in Meerwasser

Intercrystalline and transcrystalline stress corrosion cracking of austenitic Mn and CrNi steels in seawater The MnCr steels which were originally used for the construction of special ships turned out to be susceptible to intercrystalline stress corrosion cracking in seawater; later on, transcrystalline corrosion susceptibility was found, too; this latter type of corrosion appears in cold seawater and is not due to a sensilizing annealing. This type of corrosion was also found with austenitic CrNi steels in chloride solutions of higher temperature, not, however, at room temperature. The author has made an effort at defining the susceptibility regions of the particular austenitic steels. According to the results obtained it is necessary always to take account of the possibility of stress corrosion cracking when Mn based austenitic steels are used, while austenitic CrNi steels can be considered to be resistant to this type of corrosion. Sensilizing annealing, too, has a bearing on the Mn containing steels only, while the influence of temperature, potential, specimen diameter and stress does not reveal any difference between the two types of steels.