Influence of shielding gas on the transfer behavior of droplets

High-speed photography is utilized to capture an image of the arc area during the welding process.The variation in arc shape and droplet transfer behavior is compared when employing shielding gases of different components and proportions(e.g.,80％Ar+20％CO2,85％Ar+10％CO2+5％O2,65％Ar+26.5％He+8％CO2+0.5％O2)using a φ1.2 mm welding wire under 360 A current.Furthermore,the effects of various shielding gas components on the stability of the welding process are discussed.It was determined that the addition of oxygen and helium changed the arc's shape and the behavior of the droplet transfer,and the welding process stability increased.     

超低碳贝氏体钢WDB620的焊接性

本文从理论上分析了WDB620钢的焊接性；选用几种常用的可焊性试验方法对这类钢的焊接接头性能进行了评定；针对水电站施工地区多雨潮湿的环境特别提出了焊材及焊接工艺的要求。     

WDB620焊接性试验研究

本文从理论上对WDB620钢的焊接性进行了简要分析，并通过对该钢进行焊接抗裂性试验及不同线能量大小的焊接接头性能试验，说明WDB620钢属低焊接裂纹敏感性钢，具有良好的焊接性。     

700 MPa微合金高强钢焊接软化机理及解决方案

700MPa级Ti Nb成分体系控轧控冷高强钢以其生产成本低、高强韧性以及优良的可焊性,近年来在专用车轻量化领域得到广泛应用。本文采用80％Ar+20％CO2(体积分数)混合气体保护焊,对高Ti、Nb元素析出强化高强钢进行了焊接强度试验研究。结果表明,随着焊接热输入增大,焊接接头强度有降低趋势,焊接热影响区较母材硬度降低,存在软化行为,其软化机理表现在细晶强化、变形强化和析出强化效果的丧失。通过母材的B微合金化、控制焊接热输入等措施可有效缓解软化倾向,可为此种高强钢进一步推广应用提供技术参考。     

焦炉煤气自重整炉气成分与温度变化规律研究

 通过CH4 H2 CO H2O CO2 O2煤气体系的热力学模拟计算,对焦炉煤气自重整技术进行了研究。结果表明：高温、高CH4含量以及低压有利于焦炉煤气自重整。在配氧量14％,反应温度850～900 ℃,体系压力为0.3 MPa的条件下,对焦炉煤气进行自重整,则还原气平衡态组分中的氢气的体积分数可由60.0％提高到71.5％,CO体积分数可由8.0％提高到23.1％;气体的还原势为97.2％,还原气体总量约增加33％。     

Comparative Study on Processing Property Between CWW CO2 Gas Shielded Welding and SAW

 Cable welding wire (CWW) CO2 gas shielded welding is an innovative process arc welding with high efficiency, high quality and low consumption, in which cable wire is used as consumable electrode. CWW CO2 gas shielded welding and submerged arc welding (SAW) are used for contrast studies on processing property of high strength steel A36 used in ship structure. The results show that the shapes of weld seam, using CWW CO2 gas shielded welding and SAW, are good and no weld defect such as air hole, flaw, slag inclusion, incomplete fusion, lack of penetration and so on are found in the weld seam. Because the rotating of arc during CWW CO2 gas shielded welding process has a strong stirring effect on molten pool, the grain in the heat affected zone (HAZ) of the joints, using CWW CO2 gas shielded welding, is small. Tensile failure positions of joints by CWW CO2 gas shielded welding and SAW are all in the base metal, but tensile strength of CWW CO2 gas shielded welding joint is higher than that of SAW joint by an average of 2. 3%. The average impact energy of HAZ, using CWW CO2 gas shielded welding and SAW, is almost equal, but the average impact energy of the weld seam using CWW CO2 gas shielded welding is increased by 6%, and the average impact energy of the fusion line is increased by 7%. The 180° bending tests for the joints of CWW CO2 gas shielded welding and SAW are all qualified, and the joints hardness is all less than HV 355, but hardness of CWW CO2 gas shielded welding wire welding joint near the fusion line is obviously lower. It can be concluded that the properties of CWW CO2 gas shielded welding are better than those of the SAW joint, and CWW CO2 gas shielded welding is suitable for welding high strength steel A36 used in ship structure.     

Evaluation of automatic girth weldability of pipeline in special conditions

To meet the requirements of pipeline consumers abroad, in this study, an automatic gas metal arc welding type of girth welding was performed with a heat input of no more than 0.25 kJ/mm and high-strength solid-wire matching for an X70 M large-diameter UOE pipeline.An integral evaluation of the X70 M pipeline girth weldability was performed with respect to the girth-weld cold-cracking sensitivity during the welding process and the strengthening, hardening, and embrittlement of the girth weld joint after girth welding in especially rigorous welding conditions with accelerated failure characteristics.The performance of the above girth weld joint with joints welded using the main construction-field girth welding procedure was compared to ensure the good girth weldability of the X70 M pipeline.The results of this study have important supervisory significance for field-construction girth welding.Finally, the girth weldability of the X70 M pipeline was found to satisfy the field construction requirements even when the welding conditions are especially rigorous.     

非调质低焊接裂纹敏感性钢WDB620研究与开发

按照CF62钢的技术要求，设计了一种620MPa级低焊接裂纹敏感性钢。采用微合金化结合控轧控冷工艺，免去了淬火工序，以晶粒细化、沉淀强化、位错强化和贝氏体组织强化为主要手段，并对钢的可焊性进行了评价。产品已应用于水电站压力钢管系统及108t电动轮自卸车。     

Development of low-cost high-strength stainless steel for new-energy bus frames

Along with strict environmental regulation,new-energy vehicles are becoming increasingly popular due to their low emissions,and they will inevitably replace existing fossil-fuel-based buses in China.To achieve a lightweight bus body,high-strength steels are commonly used for the bus frame,but these grades are susceptible to corrosion.From the perspective of "lower life-cycle cost",high-strength stainless steel is a better bus structure choice than high-strength carbon steels,since stainless steel bus frames last 10-15 years without requiring any maintenance.The low-cost high-strength stainless steels developed by Baosteel are introduced,the yield and tensile strengths of which can be controlled to within the range of 350-700 MPa and 900-1 200 MPa,respectively,and the elongation values are above 30％.Measurements of the toughness and fatigue resistance of these high-strength stainless steels and their joints indicate that the structural integrity requirements for bus frames can be met.The results of salt spray corrosion studies indicate that stainless steels will substantially increase the service life of bus frames in wet and icy winter conditions where deicing with CaC12 is necessary for road safety.The results of our investigation clearly indicate that high-strength stainless steel is a potential bus-frame material that makes it possible to achieve substantial weight savings,excellent corrosion resistance,and prolonged operational life.     

WH80钢板的焊接性试验研究

本文从理论上分析了WH80钢的焊接性．选用几种常用的可焊性试验方法对该钢的焊接接头性能进行了评定．并对制作钢结构的焊接工艺提出了要求。     

超低碳钢RH混合喷吹Ar-CO2冶金反应特性

 钢铁生产过程CO₂的资源化利用对中国“碳达峰,碳中和”目标的实现起着重要作用。氩气驱动的RH(ruhrstahl-heraeus)真空装置是超低碳钢精炼的关键设备,利用高真空下钢水循环流动可有效脱碳、脱气和去除夹杂物。由于真空条件下CO₂可直接与钢水中碳反应生成CO,在实现脱碳的同时可促进熔池搅拌。因此,尝试将Ar-CO₂混合气体作为提升气体引入超低碳钢RH脱碳过程。首先,针对CO₂在RH脱碳条件下的冶金反应行为,通过热力学理论分析了不同压力下Fe-C-O熔体与Ar-CO₂的反应特性。其次,搭建了Ar-CO₂混合气体作为RH提升气体的工业试验平台,通过工业性试验研究了超低碳钢RH脱碳过程混合喷吹Ar-CO₂对钢水脱碳、脱氮和温降的影响。Fe-C-O熔体与Ar-CO₂反应热力学表明,在低于100 kPa和超低碳条件下,Ar-CO₂混合气体中的CO₂仍可能与钢水中碳反应,从而促进RH脱碳和脱气。工业性试验表明,喷吹100% CO₂、50% Ar+50% CO₂和100% Ar炉次出站平均碳质量分数分别为0.001 50%、0.001 57%和0.001 19%,因而混合喷吹Ar-CO₂并不会显著影响RH脱碳效率。同时,由于CO₂与钢水中碳反应十分有限,与喷吹100% Ar相比,喷吹100% CO₂和50% Ar+50% CO₂对RH脱氮效率和钢水温降没有明显影响。因此,超低碳钢RH脱碳时,完全可采用CO₂取代部分或全部氩气作为提升气体,尽管无法提高精炼效率,但仍具有显著的经济价值和环保优势。     

CO_2替代Ar净化钢液工艺研究

通过实验室试验和工业性试验,对比在CO2、Ar作为保护性气体和搅拌用气体条件下钢中氧含量和氮含量的变化。试验结果表明,CO2作为搅拌用气体,可以降低钢中氧含量,均匀成分,降低钢中夹杂物含量。     

炼钢过程底吹气体的冶炼效果对比

 基于炼钢过程底吹气体热力学及动力学进行分析,研究了底吹氧气、二氧化碳、氩气、氮气的冶炼效果。研究结果发现,氩气或氮气不与熔池元素反应,底吹时熔池温度基本不变,钢中氮质量分数较高;底吹氧气或二氧化碳时,脱碳速率和钢中氮、氢质量分数基本相同,熔池温度升高了162和45 ℃。同时发现,与底吹氧气相比,二氧化碳可减少炼钢烟尘量,炉渣中[w((TFe))]降低2.50%,[w((O))]降低90.2%。     

热镀锌双相高强钢电阻点焊焊点力学性能的研究

文章对宝钢开发的冷轧热镀锌双相高强钢电阻点焊性能作了评估,经过试验得到合适的焊接工艺范围及相应的力学性能.同时,分析比较了镀层对焊点力学性能的影响.     

500 MPa级S500QL调质高强钢板在线直接淬火(DQ)工艺研究及应用

开发了低碳(C≤0.12％)Nb-V微合金化S500QL高强度钢板,使用120 t BOF+LF+VD的洁净钢冶炼工艺,采用两阶段控制轧制(第一阶段950～1 070℃区间轧制,第二阶段开轧≤890℃、终轧≤850℃)及轧后以7～20℃/s的冷速在线直接淬火(DQ),经620～670℃,3 min/(mm·T)回火生产...     

线能量对插销临界应力的影响

本文用Ar+20％CO_2气体保护焊方法对15MnVN钢进行插销试验,试验结果表明,焊接线能量在15～40 kJ/cm范围内,插销试验的临界断裂应力高于15MnVN钢的屈服强度;也高于用J507焊条及J557MoV焊条电弧焊15MnVN钢插销试验的临界断裂应力。观察金相试样得知,15MnVN钢焊接热影响区组对焊接线能量比较敏感,脆硬马氏体及粗大铁素体的产生都会降低插销试样的临界断裂应力。为使15MnVN钢焊接热影响区获得最佳组织和最好的抗裂性能,焊接线能量应选择20～30 kJ/cm。     

含铝304和316L奥氏体不锈钢热轧板材焊接性能

 对加Al质量分数为4%的304、2%的316L不锈钢热轧板材的焊接性能进行了研究。采用手工氩弧焊（TIG）的焊接方法,利用光学显微镜对焊缝的显微组织进行分析,利用电子探针（EMPA）分析焊接母材的元素分布,并对焊接接头进行力学性能测试。组织和力学性能的研究结果表明：含铝304和含铝316L合金热轧板分别选用ER308L,ER316L作为焊接材料,经TIG焊接后,焊缝无裂纹、气孔等缺陷,接头具有良好的强度和塑性,焊接接头力学性能接近于其母材;热影响区组织与母材组织基本一致,焊缝与母材熔合良好,组织良好,加铝304和316L不锈钢具有良好的焊接性能。     

Cross-immunity to Schistosoma mansoni and S. haematobium in the hamster

The CO2 and O2 tnesions were determined in the air cells of 14-16 day old chicken eggs before and after transfer to a 21% O2 in He or SF6 atmosphere. In the former gas mixture the air-cell PCO2 (which reflects the arterialized blood PCO2) fell rapidly from 32 torr in air to 17 torr in He-O2 attaining a new steady state in 2-4 h. In the SF6-O2 mixture PCO2 rose from 36 torr in a similar period. A similar PCO2 increase was also observed when eggs were compressed to 2 atm of air while exposure to 0.5 atm with a 40% O2-N2 mixture decreased PCO2. Since gas transport across the eggshell is by gas phase diffusion, these findings can be explained by the changes in the diffusion coefficient of CO2 which increase in the presence of He and decrease in SF6. Furthermore, the diffusion coefficient is also inversely related to the absolute pressure. Quantitative prediction of the changes of PCO2 in the He and SF6 mixture cannot be made, since the binary diffusion coefficients are not necessarily applicable in a ternary gas mixture. However, effective diffusion coefficients in these multicomponent mixtures can be derived on the basis of the observed PCO2 changes.     

高炉喷吹煤气的煤造气试验

为克服喷吹煤粉给高炉冶炼带来的不利影响,提出了由造气炉燃烧普通煤产生煤气,自风口喷入高炉替代喷吹煤粉的新工艺,研究工艺参数对煤造气质量的影响规律。结果表明,气化剂流量增加,煤气中CO+H_2含量和煤气热值先升高后降低;CO+H_2含量和煤气热值随着反应温度、料层厚度、富氧率的增加而增加。当气化剂流量1.0 m~3/h、反应温度1 000℃、料层厚度1 000 mm、富氧率15%时,煤气质量达到最佳值,CO+H_2含量达到79.37%,煤气热值达到10 229.51 kJ/m~3。     

Effect of Microalloying,Principally With Vanadium,Processing Conditions and Microstructure on Resistance to CO₂ Corrosion

One driver for steel development over recent decades has been the engineering requirements of improved strength and toughness,combined with weldability,for the safe and cost effective recovery and transmission of oil and gas.This has been achieved through refinement of grain size by microalloy precipitation and thermomechanical processing.However,little attention has been paid to these significant changes in steel chemistry and processing on corrosion resistance,despite the dominance of economic carbon steel for construction in the oil and gas industries.The more common forms of corrosion are associated with the presence of H 2 S or CO 2.CO 2 in aqueous solution forms a weak acid sufficient to promote significant localized corrosion in transmission gas/oil pipelines and in well-head applications (’down-hole’).Systematic study has identified the influence of a wide range of alloying elements and different processing conditions on the resistance of low-carbon steels to CO 2 corrosion;strong carbide-forming microalloying elements such as Ti,Nb and V,along with Cr additions,and different levels of Mn,Si,Cu,Mo and Ni,have been explored,along with treatments simulating different processing conditions.The present study also emphasizes the role of V and Ti microalloying in improving the resistance of Cr-containing carbon steel to corrosion in carbonic acid and how this is influenced by microstructure and the metallurgical condition of the microalloying addition,in particular,the extent of precipitation.It is noted that some commercially available corrosion inhibitors contain V as a vanadate compound to interfere with the corrosion process and so it is suggested that V microalloying may also be beneficial if present in an appropriate form in the steel.That Ti also seems to play a role in corrosion in the steels studied is judged to be compatible with the thermodynamics of transition metal anions in the Ti-V-Cr group.