Local heat treatment of weld seams in moderate-diameter pipe produced by high-frequency current

The processes at the weld joint in local heat treatment are simulated. At heating rates typical of shop conditions, the critical points of low-carbon low-alloy steel are determined for pipe of strength class K52. Local heat treatment of such pipe welded by high-frequency current is proposed to increase the impact strength and resistance to brittle failure of the weld seam at negative temperatures.     

The effect of alumina in slag on manganese and silicon distributions in silicomanganese smelting

The distribution ratios of manganese and silicon between silicomanganese alloy and slag, in equilibrium with carbon, were investigated at 1500 °C. The alumina content of the slag was varied from about 9 to 32 pct. Both distribution ratios decreased as A1₂O₃ increased to about 20 pct and, thereafter, remained constant. The value of the “apparent equilibrium constant” displayed a maximum at about 24 pct A1₂O₃, mainly because of the variation in the values of the activity coefficients of SiO₂ and MnO. It was concluded that the slag and silicomanganese alloy in a submerged arc furnace are at, or at least close to, equilibrium.     

Influence of post-weld heat treatment on the microstructure and hardness of laser weld seams on hot-rolled TRIP 800 steel

The transformation induced plasticity (TRIP) steels effect occurs because of the martensitic transformation of retained austenite during plastic deformation,and it provides the steel with excellent strength and ductility.While welding remains a vital part of auto body manufacturing,the weldability of TRIP steels is problematic,and this prevents its adoption for many applications in the automotive industry.This present work studies the effects of welding and post-weld heat treatment on the microstructure of TRIP steels.It is found that the microstructures of the fusion zone and the heat affected zone (HAZ) are changed after high-temperature heat treatment.Hardness tests revealed that fusion zone hardness decreased with increasing of temperatures in the post-weld heat treatment on the laser weld seam.The rolling performance of the welding seam and the seam of post-weld heat treatment were also studied.     

Smelting of high-carbon ferrochrome from chromium agglomerate produced with alumina-silica flux

In a test melts, high-carbon ferrochrome is produced from chrome sinter and chrome-ore fines in an arc electrofurnace. Two types of sinter with the best performance—the best sintering rate, strength, and product yield—are studied. It is demonstrated by experimental melts that high-carbon ferrochrome can be produced from proposed agglomerates. An estimation of smelting parameters for production of high-carbon ferrochrome is made.     

Arc welding of annular seams under flux in high-strength X80 steel pipe

The relation between the content of martensitic-austenitic phase and the final temperature in accelerated cooling is investigated, in terms of the attainment of high deformability without failure. The ratio of the yield point to the strength (Y/T) in the longitudinal direction (L) of X80 steel pipe produced by UOE technology is found to be between 0.74–0.79. This indicates good deformability of the pipe. A welding technology has been developed such that the metal in the seam matches the strength of the X80 steel pipe. In industrial flexure tests, when the internal pressure is 72% of the standard yield point (SMYS) of X80 steel, the failure of X80 steel pipe welded by the given technology occurs in the basic metal, far from the annular weld.     

304不锈钢不同精炼渣碱度下夹杂物的演变

 为了提高304不锈钢的产品质量,结合生产实际,利用热力学计算和扫描电镜能谱分析方法, 研究了硅脱氧条件下,LF精炼渣碱度对304不锈钢在LF精炼、连铸过程夹杂物变化规律的影响。试验结果表明,随着冶炼过程进行,全氧质量分数和夹杂物数量依次减小。304不锈钢采用1.75高碱度炉渣,可以得到较低的全氧质量分数和夹杂物数量,但是夹杂物中Al2O3质量分数高,夹杂物熔点高。采用1.53低碱度炉渣,钢液中全氧质量分数较采用高碱度炉渣高,但是夹杂物中CaO、Al2O3质量分数相对较低,SiO2和MnO质量分数较高,夹杂物熔点低。针对304不锈钢产品可以采用不同的生产工艺路线来满足产品的不同需求。     

炼铜炉渣浮选回收铜的试验研究

对某冶炼厂连续吹炼炉炼铜炉渣进行了浮选回收铜试验研究。试验采用一次粗选、二次精选、二次扫选工艺流程,获得含金品位5.07 g/t、银品位293 g/t、铜品位29.31%的铜精矿,铜回收率为90.17%,金回收率为98.43%,银回收率为95.24%。     

Experimental study on slag splashing with modified vanadium slag

Slag splashing is the most effective technology to improve the furnace campaign of converter; however, due to the great difference of composition between the vanadium slag and the steel slag, the technology has not been applied in the vanadium extraction converter. To solve the serious problem of lining erosion in the vanadium extraction converter, in this paper, slag splashing with modified vanadium slag was studied. The results showed that the purpose of adjusting the state of vanadium slag can be achieved through the modification. The modified slag had good slag splashing performance. After slag splashing, the thickness of the furnace was increased by more than 10?mm. The content of CaO in the modified vanadium slag can be controlled less than 3%, and the quality of vanadium slag and semi-steel was not obviously affected. The metallic iron content in the slag was greatly reduced, which was beneficial to reduce the iron loss in the vanadium extraction process.     

提钒转炉溅渣护炉试验研究

溅渣是提高转炉炉龄最有效的技术,但由于钒渣与钢渣成分差异较大,溅渣护炉技术尚未在提钒转炉上得到应用.为解决提钒转炉炉衬侵蚀严重的问题,对改性钒渣溅渣进行了研究.结果表明,通过改性可以达到调整钒渣状态的目的.改性后的钒渣具有良好的溅渣性能,溅渣后炉厚增加10 mm以上.改性钒渣中w(CaO)可控制在3％ 以下,对钒渣和半...     

Manipulation of slag separation properties from pig iron nuggets with flux additions to dried greenball mixture

Pig iron nugget process is one of the direct smelting processes developed as an alternative to the traditional blast furnace process. Throughout the process, slag-free pig iron nuggets, which have similar properties to the blast furnace pig iron and white cast iron, are produced by single-stage heat treatment of dried greenballs. During the process, slag separation from the metallized areas can be enhanced by adjustment of the slag’s chemical and physical properties. The objective of this research was to investigate the effects of flux addition rates (basic to acid ratio) to the dried greenball mixture on pig iron nugget production and slag separation. Thus, this study involved the heat treatment of six different greenball mixtures, which contained various amounts of limestone addition (basic to acid ratios, 0, 0.63, 1.02, 1.42, 1.85, and 2.29) utilizing a laboratory-scale resistance box furnace or simultaneous differential scanning calorimetry and thermalgravimetric analyzer. The samples produced by heating in the box furnace were analyzed for their morphological and chemical properties utilizing optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), macroscopic observations, iron titrations, and atomic absorption spectroscopy. It was determined that the highest percentage of iron yield in the nugget for the process and the highest distribution of iron in magnetic slag were obtained when utilizing the greenball mixture, which contained 7.5 wt% limestone as flux (basic to acid ratio of 1.42).     

埋弧焊剂含水率与熔敷金属扩散氢关系研究

埋弧焊熔敷金属扩散氢的含量对焊缝质量有较大影响,其含量多少主要取决于焊剂中的含水率多少.通过控制焊剂含水率的方式控制熔敷金属扩散氢含量,可有效提高焊缝质量.选取某进口焊剂为研究对象,采用卡尔费休法测定焊剂含水率,采用热提取法测定扩散氢含量,建立熔敷金属扩散氢与焊剂含水率之间的关系曲线,有效地为焊管生产过程中的焊剂质量管控提供了技术支撑.     

镍渣制备微晶玻璃的结晶动力学及结晶化过程

探讨以镍渣为主要原料采用熔融法制备建筑用微晶玻璃.研究引入Cr₂O₃作为晶核剂的镍渣微晶玻璃的成核及晶化过程.利用DSC测试来确定基础玻璃的晶化温度,并利用修正的Johnson-Mehl-Avrami(J/VIA)方法初步计算以镍渣为主要原料所制备的基础玻璃在加入质量分数2%的Cr₂O₃作为晶核剂后的结晶活化能E及结晶动力学参数k(T_p),计算结果分别为E=371.1kJ·mol^-1,结晶动力学参数k(T_p)=0.29.采用XRD、SEM和光学显微镜测试、分析及观察方法来鉴定、分析微晶玻璃试样的主晶相及微观结构.结果显示,加入晶核剂的基础玻璃从930℃开始均匀地析出透辉石相晶体;随着温度的升高,晶体尺寸也逐渐增大,在温度达到950℃后,对样品进行30min保温热处理,样品中晶体尺寸达到10~15μm.     

利用炼钢渣来增殖海藻的初探

在钢铁生产过程中产生大量的废渣、排放大量的CO2;大气中CO2气体的增多造成温室效应,使得全球气温升高。转炉渣中含有对藻类植物生长有益的营养元素,如果可以利用转炉渣作为营养源来增殖藻类固定CO2,既利用了钢渣,又能够减少大气中的CO2。研究用1号炉渣和2号转炉渣对于扁胞藻进行了一级培养和对螺旋藻进行了一级、二级培养。结果表明,加入转炉渣可以增殖扁胞藻和螺旋藻;在螺旋藻的一级培养中,1号转炉渣的最佳加入量为0.4 g/L,2号转炉渣为0.06 g/L;同时要考虑到加入转炉渣后透光度对海藻生长的影响。     

低配碳含碳球团组分对低温熔分性能的影响

根据低配碳直接还原—低温熔分工艺制备粒铁的技术思想,考察了渣相成分对熔分开始时间及熔分后铁收得率的影响.试验结果表明,随着CaO添加量的增加,球团熔分开始时间先减小后增加.当CaO添加量为2.0％时,熔分开始时间最短.n(C)/n(O)为0.8时,渣相熔点较低,流动性较好,有利于渣铁分离.综合考虑熔分时间、铁收得率及能耗等,实验室条件下的最佳工艺参数为n(C)/n(O) =0.8,CaO添加量为2.0％,反应时间40 min(熔分开始时间30 min+熔分时间10 min).该条件下铁收得率约为85％,铁粒中铁含量约为94％,金属化率达95％以上,可作为优质的电炉炼钢原料.     

热浸镀无铵助镀工艺参数对镀层质量的影响

氯化铵在浸镀过程中会分解生成氨气,对周边环境产生污染。无铵助镀是顺应环境保护和行业发展趋势应运而生的新工艺。通过单因素试验和工业实践,确定了无铵助镀剂最佳工艺参数和工业应用范围。试验表明该工艺稳定性较高,助镀剂不仅能够在室温条件下应用,还能在pH值较低、FeCl2质量浓度较高、环境湿度较大的条件下获得光亮、外观平整的镀层。电化学试验结果表明,使用无铵助镀剂所获镀层的耐蚀性能不低于使用传统锌铵助镀剂的耐蚀性能。     

铁棉联产的优质矿渣棉生产工艺

传统的矿渣棉生产工艺是通过冲天炉把冷态物料熔融.较先进的冲天炉能耗水平在445 kg标准煤/吨棉左右.本文提出的"铁棉联产工艺"是将热态的高炉渣转移至调质炉,采用氧煤混喷二次加热技术进行提温,按照既定配比调质后,直接用于生产矿渣棉的工艺.该工艺不仅可大幅降低矿渣棉生产的能耗,同时对于节约用水、提高高炉渣的附加值有着积极作用.铁棉联产工艺是建立在熔融态高炉渣热能完全利用的基础上,其能耗水平在240 kg标准煤/吨棉.充分考虑其他配套设施,铁棉联产的矿渣棉工序能耗更低、生产优势突出.