Q345B钢中硫化物及微合金碳氮化物析出热力学分析

为改善Q345B微合金钢铸坯塑性,控制裂纹产生,对Q345B钢中硫化物及微合金碳氮化物析出热力学进行了分析。计算结果表明：1）钢液中不可能析出氮化物、碳化物和硫化物;2）钢液凝固过程中硫化锰在1472℃、氮化钛在1467℃时具备析出的热力学条件,而其它氮化物、碳化物则不具备析出条件;3）在奥氏体相中,氮化铝、碳化钛,碳化钒和氮化钒的平衡析出温度分别为1027℃、977℃、727℃和777℃。     

氧含量及脱氧方式对30MnVS铸态组织硫化物形貌的影响

硫系易切削钢中主要依靠硫化物夹杂来改善切削性能,分布均匀的球状硫化物最有利于切削加工,且对钢材力学性能的损害也是最小的。本文研究了氧含量以及脱氧方式对30MnVS铸态组织中硫化物形貌的影响。结果显示,舢脱氧样品中,由于Al含量较高硫化物都是以沿晶界分布的杆状硫化物为主,主要以共晶反应的形式在凝固的最后阶段形成。采用Mn—Si脱氧,降低样品中Al含量,凝固时形成的硫化物主要以球状或液滴状为主,且绝大部分硫化物中含复合氧化物核心。     

Ce在钢中存在形式及作用的研究进展

Ce是活泼元素。钢液中加入Ce形成含铈硫氧化合物，能够脱氧、脱硫和脱砷，净化钢液，促进钢液凝固形核、细化组织；热力学计算表明CeAlO₃生成自由能最低，生成不同含硫氧化合物与钢液中含氧量、含硫量有关系；微量Ce能固溶于钢中，提高钢的抗腐蚀性能；Ce在钢中也能析出CeFe₂、Fe₄Ce₄C₇或CeC₂等脆性相，降低钢的性能。钢液中形成大量CeAlO₃易聚集堵塞浇注水口，形成Ce₂O₃或Ce₂O₂S分布在基体组织中，使钢在高温轧制时开裂，降低钢的性能。稀土加入低氧钢中能调控碳扩散，优化钢的显微组织和力学性能。     

P110钢在元素硫沉积环境中的腐蚀过程探讨

实验模拟了普光气田元素硫沉积环境,利用SEM、EDS等技术研究了腐蚀产物膜的截面元素分布及腐蚀产物膜的形貌和成分,分析了P110钢在该环境中的腐蚀过程。结果表明:P110钢首先发生氧化腐蚀,进而发生硫化腐蚀。由于含硫离子对P110钢腐蚀电位的影响,Cl-表现出较强的侵蚀性,它借助硫化物膜向腐蚀产物膜的内层扩散,并在基体界面发生点蚀。同时,S2-通过腐蚀产物膜向内扩散,在氧化物膜与硫化物膜之间形成新的硫化物膜。     

00Cr14Ni14Si4奥氏体不锈钢中微量铝硫与锻造裂纹

００Ｃｒ１４Ｎｉ１４Ｓｉ１４钢的锻造裂纹与钢中Ａｌ，Ｓ以及由之形成的氧化物和硫化物含量过高有关。钢在模铸凝固和冷却过程中形成夹杂物年，呈点链状的氧化物和晶界析出的薄片Ｙ相在热加工时弱化了晶界降低了钢的导热性和高温塑性，从而在夹杂偏析区显示出宏观的热加工裂纹。     

Mn-Nb-RE钢中非金属夹杂物的研究

Mn-Nb-RE钢中的非金属夹杂物主要是氧化物、硫化物和碳化物。研究结果表明，为了使硫化物充分变质，以改善Mn-Nb-RE钢板横向冲击韧性、塑性和宽冷弯性能，当钢中稀土和硫之比控制在RE／S≈3时，力学性能可获得最佳值。钢中的RE／S比值不同，对硫化物的变质程度有较大影响，所形成的硫化物类型也有所不同。     

一种Ni-Cr-Mo镍基合金焊丝凝固过程元素偏析及相转变规律研究

为了对Ni-Cr-Mo镍基合金焊丝进行成分优化设计,本文通过热力学模拟计算方法研究了镍基合金焊丝凝固过程元素的偏析规律,并分析了合金元素对析出相的影响.研究表明:镍基合金焊丝平衡态主要的析出相为γ、M6C、P和μ相;在非平衡凝固状态下,随着凝固过程的推进从液相中析出M6C、P和σ相;随着Cr含量的增加,μ相的初始析出温...     

氮在浆体输送管线用钢中的作用和行为

研究了氮在浆体输送管线用钢中的作用和行为.钢中加入0.007-0.02%N和相应数量的Ti,以保证TiN从奥氏体中析出,但不从液相中析出.充分利用固溶氮的固溶强化作用和析出氮化物对铁素体晶粒尺寸细化和促进高韧性针状铁素体的形成的有利作用.两者的有效结合使钢获得了良好强韧性配合及耐腐蚀性能.     

O＇-Sialon-BN复合材料在钢液中的侵蚀机理

研究了O＇-Sialon-BN复合材料在钢液中侵蚀的热力学和动力学过程,结果表明,O＇-Sialon-BN侵蚀的主要原因是钢液中的[Mn]与试样晶粒间少量玻璃相中的SiO2发生化学反应生成MnO-SiO2-A12O3低熔点渣相并溶解;同时.钢液中的[O]与试样中的O＇-Sialon反应生成SiO2和A12O3,产物SiO2又被钢液侵蚀掉;但BN不易与钢液反应因此,BN晶粒在侵蚀层内壁聚集,逐渐形成较厚的扩散层,阻碍了试样在钢液中侵蚀反应的进行O＇-Sialon BN复合材料抗钢液侵蚀的动力学分为两段控制:前期由界面化学反应控制,后期由扩散控制,由此分别得出相应的侵蚀速度方程。     

酸性X气田生产井环空套管腐蚀规律研究

酸性X气田生产过程中多口井出现了环空带压和环空气/液样含H₂S和硫化物的现象,油层套管中110SS抗硫材质面临严重的腐蚀风险。为了获取真实井筒环境下抗硫套管的腐蚀规律,在高温高压反应釜中采用腐蚀挂片的方法开展了110SS抗硫套管在气相和受污染环空保护液中的腐蚀评价实验,以及抗硫套管与镍基合金套管连接处在受污染环空保护液中的电偶腐蚀评价实验,并利用金相显微镜、扫描电镜和能谱对试样腐蚀表面和腐蚀产物进行了观察分析。实验结果表明：抗硫套管在液相中的腐蚀速率很低,温度对腐蚀速率没有明显的影响;当温度高于100℃时,抗硫套管在气相中的腐蚀变得非常严重,腐蚀速率高达0.947 3 mm/a;抗硫套管和镍基合金套管连接处在液相中发生了严重的电偶腐蚀,抗硫套管试样表面出现较大的腐蚀坑,腐蚀速率大于工程设计允许的0.076 mm/a。获得的真实井筒环境下的抗硫套管腐蚀规律将为后期制定防腐控制措施、预测套管剩余强度以及评价井筒安全提供准确的参考依据。     

Gender differences in publication productivity in psychology in India

An analysis of gender differences in psychology in India provides quantitative and qualitative assessment of R&D output contributed by psychologists with the indication of the trend of growth, skewness, relatedness, co-authorship pattern of productivity.     

Metrology in Chemistry in Germany

The system for Metrology in Chemistry in Germany is described. At the national standards level, a network of high-level chemistry institutes coordinated by the national metrology institute, PTB, provides the primary references for chemical measurements. A dissemination mechanism employs chemical calibration laboratories accredited within the framework of the German Calibration Service (DKD). They act as “multipliers” between the national standards level and the user level by providing the user with calibration means which are traceable to the SI via national standards. Traceability structures in clinical chemistry, electrochemistry, elemental analysis and gas analysis are described     

Natural radioactivity in drinking water in private wells in Finland

Natural radioactivity in drinking water was determined in population-based random study of 472 private wells. The mean concentrations of (222)Rn, (226)Ra, (234)U, (238)U, (210)Pb and (210)Po in drilled wells were 460, 0.05, 0.35, 0.26, 0.04 and 0.05 Bq l(-1), and in wells dug in the soil were 50, 0.016, 0.02, 0.015, 0.013 and 0.007 Bq l(-1), respectively. Approximately 10% of the drilled wells exceeded a radon concentration of 1000 Bq l(-1) and 18% a uranium concentration of 15 microg l(-1). The mean annual effective dose from natural radionuclides for a drilled well user was 0.4 mSv and 0.05 mSv for a user of a well dug in the soil. The effective dose arising from (222)Rn was 75% of the total of all natural radionuclides for drilled well users. As regards long-lived radionuclides, (210)Po and (210)Pb caused the largest portion of the effective dose. The dose arising from (238)U, (234)U and (226)Ra was only 8% of the total of all natural radionuclides.     

Natural radioactivity in drinking water in private wells in Finland

Radiation Protection Dosimetry     

Radioactivity in building materials in Iraq

Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials.     

Optische in situ Schichtdickenmessung in Bedampfungsanlagen. Optical in situ film thickness monitoring in coating systems

Optical film thickness monitoring is more precise than crystal monitoring. The optical measurement makes use of the fact that the intensity of a monochromatic light beam which is reflected on a film will change periodically with increasing film thickness. The measurement is performed at an exchangeable test glass that is positioned beside the substrates and is therefore coated in the same way as the substrates. The accuracy of cut‐off is achieved by a “fit” of a theoretical curve shape to the measured values. Order filters are used to ensure that, at a certain wavelength, higher deflection orders do not influence the measurement when a monochromator grating is used.