高速线材生产的弹簧钢盘卷的表面脱碳分析

从金相角度对高线生产的弹簧钢盘卷的表面脱碳进行了分析，找出相关的影响因素，并针对实际情况提出了相应的改进方法。     

AOD冶炼脱碳反应模型与计算机模拟

AOD冶炼中,终点碳和终点温度的命中率是提高生产率和产品质量的关键。由初始温度,初始成分及补加合金量等原始数据,通过本模型可预报要达到目标终点碳所需要的脱碳时间以及相应的终点温度。本模型计算得到的终点碳与实际终点碳,在同等条件下,两者极为接近,可作为一般AOD冶炼中预报终点碳与脱碳时间关系之用。通过分级调整O2、Ar、N2气比例得到最佳脱碳效果,终点碳命中率可提高到98％以上,最高温度可以控制不超过1750℃,延长炉衬寿命。     

电弧炉炼钢过程钢中临界碳的实测和脱碳操作实践

经测试得出，在临界[C]为0．2％～0．8％、供氧强度为定值时，脱碳速度主要取决于[C]向钢渣反应界面的扩散。70t UHP DC电弧炉脱碳实践表明，采用熔清后全程小角度吹氧，熔池沸腾良好后再喷碳粉造泡沫渣，渣碱度为2．0～2．5，避免形成低碱度泡沫渣，在临界[C]范围内进行通电脱碳操作，利用电路磁场搅拌作用，促进[C]向反应界面扩散，可避免大沸腾事故的发生。     

含碳微细粒难处理复杂金矿选矿试验研究

针对某含碳超显微包裹体难浸金矿石,分别开展了常规氰化浸出探索试验、优先浮碳再细磨浮金探索试验、细磨焙烧预处理再氰化提金探索试验。试验结果表明,采用常规氰化时金的浸出率仅为14.01%,即使进行脱碳处理后,金浮选的回收率也仅达到51.82%。该类型矿石若要解决受含碳和包裹金影响的问题,有效的途径之一就是进行焙烧预处理。矿石经细磨后,采用“焙烧-水洗-碱浸-氰化”的工艺流程,金的浸出率可达87.57%,从而使金得到了较好的回收。     

Decarburization of TiC in Ni activated sintered W–xTiC (x = 0, 5, 10, 15 wt%) composites and the effects of heat treatment on the microstructural and physical properties

Blended elemental W–xTiC (x = 0, 5, 10, 15 wt%) powders were mechanically alloyed (MA’d) for 30 h in a SPEX Mixer/Mill at room temperature. About 1 wt% Ni was added to each MA’d batch as sintering aid which were further milled for 1 h. MA’d powders were sintered at 1400 °C for 2 h under Ar, H₂ gas flowing conditions and annealed at 1600 °C for 6 h under Ar atmosphere. Microstructural characterizations of as-sintered and annealed samples were conducted using XRD and SEM. XRD patterns of the as-sintered and annealed samples revealed the presence of the matrix W and Ni phases, whereas (Ti_x,W_1−x) solid solution phase came into existence after annealing. In addition to XRD patterns, hot combustion and infrared detection measurements revealed the decarburization of TiC. Relative density values varied between 85.2% and 96.4% after sintering. The density values of sintered samples decreased with increasing TiC content. After annealing, a maximum relative density value of 99.8% was achieved. Vickers microhardness values varied between 5.11 GPa and 10.79 GPa for as-sintered samples and a maximum microhardness value of 8.1 GPa was measured after annealing. Wear resistance of the as-sintered samples increased with increasing TiC content.     

Influence of Oxygen Dissociation on the Oxidation of Iron

Kinetics of the oxidation of iron in fluxes of atomic and molecular oxygen have been studied over a wide temperature range from 573 to 1273 K. The influence of oxygen pre-dissociation on the oxidation rate was found negligible at 573–1073 K. At temperatures above 1073 K, when only FeO is formed, the rate of iron oxidation in atomic oxygen is substantially higher than that in molecular oxygen. Decarburization occurs during the first stage of oxidation of iron containing carbon. The rate of carbon elimination in atomic oxygen exceeds that in molecular oxygen due to the higher chemical potential of atomic gas.     

Mechanical properties of WC–Co coatings with different decarburization levels

In this study, two kinds of WC–Co coatings with different decarburization levels were deposited by high-velocity oxy-fuel(HVOF) spraying using the ultrafine WC–Co composite powder and commercial micronsized powder, respectively. The hardness and elastic modulus were measured on the top surface and cross sections of the prepared coatings by the nanoindentation method. The results show that the ultrafine-structured coating has much higher density and inhibited decarburization than the conventional coating, which thus results in higher hardness and elastic modulus values than the micronsized coating. The wear resistance of thermal-sprayed cermet coatings greatly depends on the cross-sectional hardness and elastic modulus which reflects the bond strength between splats to some extent. Based on the analysis, a better understanding of the microstructure and properties in cermet coating materials was obtained.     

摩擦火花瞬时高温对中高碳钢中碳的影响

选取42CrMo、60Si2Mn、GCr153种常见的中高碳钢理论分析和检测验证两方面对高速打磨过程中摩擦火花瞬时高温是否会对中高碳钢表面形成脱碳层,从而影响中高碳钢中碳含量的检测进行探讨、验证。结果表明高速打磨过程中摩擦火花瞬时高温无法达到中高碳钢表面脱碳所需的温度,并且在实际检测中标准物质11次测试结果的RSD在0.499%~0.698%,测试结果的平均值和认定值的差值均在标准样品证书的不确定度范围内。因此高速打磨过程中摩擦火花瞬时高温不会影响中高碳钢中碳含量的检测。     

Applied electric field on the reaction between submerged entry nozzle and alloy in the steel

In this study, the reactivity between nozzle and submerged entry nozzle and alloy elements in the steel (Al and Ce) under different electric field conditions was investigated. The results show that the decarburization of the nozzle is an important factor affecting the clogging behavior and steel quality. The external electric field directly affects and changes the decarburization, clogging, and reaction behavior between the nozzle and alloy in the steel. If the chemical reaction force between alloys and the nozzle is greater than the applied electric field force in actuality, the clogging will also occur on the submerged entry nozzle. In the future, this new method of controlling and changing the interfacial electric fields can be used to solve the problem of decarburization and clogging of the submerged entry nozzle.     

44Si2CrV 钢弹簧弹性减退机理的研究

研究了影响44Si2CrV钢弹簧在低于屈服强度的应力下长时间加载引起自由高度变化的因素。结果表明,44Si2CrV钢弹簧在900 MPa 的应力下压缩72 h,自由高度的缩短由两部分组成：表面脱碳层的塑性变形,造成对内部材料的牵制而使部分弹性变形不能恢复,由此所造成的弹簧自由高度缩短占总变形量的84%;钢的室温蠕变,占自由高度缩短的16%。