控制钢中氢含量的工艺措施

氢是钢中的有害元素,过高的氢含量可引起钢的氢裂、白点缺陷。分析了季节、钢液温度、真空度、保真空时间、钢包顶渣对钢中氢含量的影响,提出了控制钢中氢的技术措施。实施后,钢中氢含量下降了8.14%。     

重轨钢中的氢及其控制工艺

介绍了钢中氢对钢质量的影响以及对重轨钢的危害,对钢液中氢的检测方法和检测设备作了简单说明,阐述了采用转炉→LF→RH(VD)→连铸工艺生产重轨钢时,钢中氢的来源及其过程氢含量,并提出了有效控制重轨钢中氢含量的措施及实施效果。     

钢中氢含量的测定和分析

介绍了利用RH600氢分析仪测量钢中氢含量时,不同的氢含量标样和加工方法对测定值的影响,并利用所确定的最佳测试条件研究了钢中氢含量随时间的变化趋势。结果表明,试样在加工时,使用冷却液可减少结果偏差;钢中氢含量在一定时间内随放置时间的延长而降低。     

重轨钢氢含量影响因素分析

在钢液吸氢动力学和热力学分析的基础上,对重轨钢生产中各工艺环节的氢含量进行了测量,并分析了季节变化、合金炉料及真空处理等因素对重轨钢氢含量的影响,提出了相应的解决措施,使重轨钢氢含量超标的罐次由1.2%降至0.4%。     

钢液氢含量检测技术研究

测量钢液氢含量的方法有离线定氢和在线定氢。离线定氢通过从钢液中取样,凝固后实验室检测氢含量。在线定氢通过测量出钢液的平衡氢分压后利用Sievert定律换算出氢含量。与离线定氢相比,在线定氢影响因素少,系统重现性好,测量周期短,满足真空处理、连铸等快节奏定氢的需要。     

脉冲加热惰气熔融法测定钢中氢

叙述了脉冲加热惰性气氛熔融法测定钢中氢含量的条件试验，并用选择的最佳分析条件测定了钢中氢的含量。     

EMGA-621W定氢仪测定钢材中氢含量

介绍EMGA-621W定氢仪测定钢材中氢含量的原理，并分析制样对钢中氢测量的影响，找出制样方法。以测得钢中氢的准确值。     

测定钢中氢的新方法及其在生产检验中的应用

自从人们认识到氢会造成钢的表面缺陷、脆裂、白点和裂纹以后,便不断努力探索适用的测定钢中氢含量的方法[1]。新的快速冶金法的出现使这种探索更为迫切。试验室如果不能及时检测钢中的氢含量,以便     

降低重轨钢氢含量控制实践

重轨钢对氢含量要求极其严格,其含量的高低对铁路安全运行至关重要。在传统炼钢工艺中,通过控制原辅料、合金和耐材中的水分,可以使钢中氢含量降低到一定水平,但与铁路标准要求尚有一定差距。通过研究炼钢RH精炼过程中不同真空时间下氢含量变化,连铸铸坯在不同缓冷条件下氢含量变化,确定了最佳真空处理时间、缓冷工艺等,在兼顾生产成本的同时,实现重轨钢中氢含量完全满足铁路标准要求,保证重轨在线服役质量和列车安全运行。     

厚板生产中对氢含量的控制

当钢中一定数量的氢达到一个临界值时就会产生各种类型的裂纹 ,这种现象是由于过多的内部氢压力以及与裂纹形成有关的材料缺陷例如非金属夹杂物造成的。因此可以通过避免过量的氢或者提高裂纹临界值来防止裂纹形成。在特定的应用中 ,钢中氢含量可能由于腐蚀反应例如在潮湿的 H2 S环境中 ,在金属表面产生原子氢的吸收和扩散使钢中氢含量增加。这种现象能够产生氢诱导裂纹 HIC。其破坏机理以及防止氢诱导裂纹的主要方法详述如下 :1　前言钢中氢是有害的 ,其破坏机理是铁中氢的溶解行为 ,液态铁中氢的溶解度比在固态铁中高 (见图 1 ) ,由于液…     

利用TDS方法研究氢在两种马氏体钢中的扩散

采用TDS方法研究了氢在两种马氏体钢中的扩散行为,结果发现氢在高铬低铝的D2钢中的扩散显著低于低铬无铝的D1钢。从充氢试样室温放置时氢体积分数下降规律可知,氢在D1钢和D2钢中的扩散系数分别为1.52×10-7和5.3×10-8cm2/s。D2钢中存在大量细小的碳化物,既对氢的扩散起到阻碍作用,降低氢的扩散系数,又可作...     

轧制下线温度对15CrNiMo硬度及析氢行为的影响

为了优化牙轮钻头用15CrNiMo圆钢轧制工艺,降低圆钢氢含量及硬度,减少白点缺陷以及应力开裂的质量风险,对比了不同轧制下线温度对圆钢宏观硬度、显微硬度以及显微组织的影响,并采用升温脱氢分析方法(thermal desorption spectroscopy,简称TDS)对圆钢析氢曲线、氢含量等进行了对比分析。结果显示,升高轧制下线温度可以有效提高钢材铁素体组织比例,从而使钢材整体硬度降低,另外也有助于减少钢中的氢含量。     

连铸坯脱氢退火数值模拟

采用数学模拟方法研究钢轨钢连铸坯脱氢退火行为,分析不同退火温度、退火时间条件下连铸坯脱氢效果,优化了脱氢退火工艺。在脱氢退火过程中,连铸坯角部和边部的氢含量快速降低,而连铸坯中心氢含量在加热段后期开始降低;随着退火温度的升高,连铸坯中心脱氢的起始点明显提前,最大脱氢速率显著增加。随着均热段时间逐渐延长,连铸坯中心氢含量明显降低,但脱氢速率的增加幅度逐渐减小。通过优化脱氢退火工艺参数,连铸坯中心氢的质量分数能够降低至0.6×10?6,脱氢效果显著。      

转炉钢水氢含量的来源及控制

以转炉钢水氢含量为研究对象,借助钢水定氢仪对钢水增氢原因进行了摸索和分析,有针对性地提出了预防控制措施.措施实施后,转炉钢水氢含量由控制前的平均7.3 ×10-6降低到现在的（3.0 ～3.5）×10-6.     

A study of the hydrogen-induced degradation of two steels differing in sulfur content

Two steels with different sulfur contents: 0.003 and 0.024 wt pct, were cathodically charged under three different conditions and brought to fracture in tension immediately after charging or after aging at room temperature. All hydrogen charged specimens showed embrittlement, with a little higher loss of ductility in the high sulfur steel. The hydrogen embrittlement was reversible in both steels when specimens were charged in arsenic-free sulfuric acid solution at room temperature but was irreversible when charged in arsenic-containing acid at the same temperature. After charging in molten salts at 200 °C, some of the low sulfur steel specimens exhibited irreversible hydrogen damage with the appearance of quasicleavage fractures, while all high sulfur steel specimens were restored to the uncharged ductility by aging at room temperature. These results are interpreted by assuming that an increased sulfur content in steel increases the density of trapping sites for hydrogen at the sulfide/matrix interfaces. These traps are inactive above 150 °C and become operative after cooling. Therefore, at the same hydrogen content in steel after cooling, the greater content of sulfur results in a decreased activity of the lattice dissolved hydrogen, hence in reduced embrittlement.     

Production of low-sulfur steel with limited hydrogen content

The converter production of steel with low sulfur content is analyzed. Existing desulfurization methods greatly increase the hydrogen content in the steel. Options for reducing the hydrogen content associated with the solid slag-forming mixture are outlined. The influence of the storage time and conditions on the quality of fluidized lime and correspondingly on the steel’s hydrogen content is discussed.     

Effect of the production factors on the hydrogen saturation of steel

The available data on the influence of hydrogen on the steel quality and its main hydrogen-induced defects are analyzed. The factors that influence the hydrogen content in steel under conditions of the oxygen-converter plant of the Magnitogorsk metallurgical works have been revealed. The methods of decreasing the hydrogen content in steel are considered.     

Internal hydrogen-induced subcritical crack growth in austenitic stainless steels

The effects of small amounts of dissolved hydrogen on crack propagation were determined for two austenitic stainless steel alloys, AISI 301 and 310S. In order to have a uniform distribution of hydrogen in the alloys, they were cathodically charged at high temperature in a molten salt electrolyte. Sustained load tests were performed on fatigue precracked specimens in air at 0 ‡C, 25 ‡C, and 50 ‡C with hydrogen contents up to 41 wt ppm. The electrical potential drop method with optical calibration was used to continuously monitor the crack position. Log crack velocityvs stress intensity curves had definite thresholds for subcritical crack growth (SCG), but stage II was not always clearly delineated. In the unstable austenitic steel, AISI 301, the threshold stress intensity decreased with increasing hydrogen content or increasing temperature, but beyond about 10 wt ppm, it became insensitive to hydrogen concentration. At higher concentrations, stage II became less distinct. In the stable stainless steel, subcritical crack growth was observed only for a specimen containing 41 wt ppm hydrogen. Fractographic features were correlated with stress intensity, hydrogen content, and temperature. The fracture mode changed with temperature and hydrogen content. For unstable austenitic steel, low temperature and high hydrogen content favored intergranular fracture while microvoid coalescence dominated at a low hydrogen content. The interpretation of these phenomena is based on the tendency for stress-induced phase transformation, the different hydrogen diffusivity and solubility in ferrite and austenite, and outgassing from the crack tip. After comparing the embrittlement due to internal hydrogen with that in external hydrogen, it is concluded that the critical hydrogen distribution for the onset of subcritical crack growth is reached at a location that is very near the crack tip. Formerly Research Assistant, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign.     

降低重轨钢的氢含量

研究重轨钢中氢的来源及控制手段.分析表明,钢水增氢主要是外加材料,尤其是增碳剂带入的水分所引起的.通过控制各工序加入材料的水分,有利于减少重轨钢中的氢含量.通过VD真空脱气处理,能有效地脱去钢液中的氢.