Improving creep strength of the fine-grained heat-affected zone of novel 9Cr martensitic heat-resistant steel via modified thermo-mechanical treatment

The infamous type Ⅳ failure within the fine-grained heat-affected zone (FGHAZ) in G115 steel weldments seriously threatens the safe operation of ultra-supercritical (USC) power plants.In this work,the traditional thermo-mechanical treatment was modified via the replacement of hot-rolling with cold rolling,i.e.,normalizing,cold rolling,and tempering (NCT),which was developed to improve the creep strength of the FGHAZ in G115 steel weldments.The NCT treatment effectively promoted the dissolution of preformed M_(23)C_(6)particles and relieved the boundary segregation of C and Cr during welding thermal cycling,which accelerated the dispersed reprecipitation of M_(23)C_(6) particles within the fresh reaustenitized grains during post-weld heat treatment.In addition,the precipitation of Cu-rich phases and MX particles was promoted evidently due to the deformation-induced dislocations.As a result,the interacting actions between precipitates,dislocations,and boundaries during creep were reinforced considerably.Following this strategy,the creep rupture life of the FGHAZ in G115 steel weldments can be prolonged by 18.6%,which can further push the application of G115 steel in USC power plants.

高温高应变率下G550冷弯钢的动态力学行为

为研究G550冷弯钢在高温和高应变率下的动态力学性能,采用高温同步控制霍普金森拉杆装置,开展了不同温度下的高应变率拉伸试验,并在高速液压拉伸试验机上进行了室温下的中应变率拉伸试验。通过获得的应力-应变曲线,得到了材料的本构模型,结合微观形貌分析,探究了温度和应变率对流变应力的影响。结果表明:G550冷弯钢具有明显的应变率强化和温度软化效应。在特定的高应变率范围内(1000~1500 s-1),温度对流变应力的影响大于应变率。基于温度软化系数随温度变化的特征,提出了G550冷弯钢的修正Johnson-Cook本构模型。该模型可以较好地描述G550冷弯钢在高温和高应变率下的动态力学行为,从而为G550冷弯钢在高温、爆炸冲击相关的有限元仿真提供参考。

Comparative Study on Microstructures of Zincalume Steel(G550)Welded Joint Between Metal Inert Gas and Laser Beam Welding

Zincalume steel(G550)is commonly used in various construction fields because of its high corrosion resistance and good mechanical properties.In recent years,a number of steel companies have massively produced zincalume steel(G550)with large volumes of waste.For the reduction of massive industrial wastes,the zincalume steel(G550)was welded in the lap joint configuration using different welding parameters in the metal inert gas(MIG)welding and laser beam welding(LBW)process in this study.The MIG welding and LBW are more welcomed welding methods due to their high efficiency and low cost.However,they are different as the LBW offers welding speed three to five times faster than MIG welding,while LBW’s heat transfer to workpieces is much less than MIG welding,which can avoid some distortions.The microstructure of zincalume steel(G550)was investigated using scanning electron microscopy(SEM)and the microstructure characterizations of welded specimens were analyzed.The experiment found the columnar dendrites extended under the heat flow direction during the MIG welding and LBW process.Thus,the columnar grains were formed in between the equiaxed zone and fusion zone(FZ)at high heat input and slow cooling rate.Moreover,the grain size of FZ was comparatively smaller than heat affected zone(HAZ)and base metal(BM).

G550高强度冷成型钢高温力学性能瞬态试验研究

冷成型钢高温材料特性是进行冷成型钢结构抗火设计及数值模拟的重要参数。现有的钢材高温材性数据大多基于稳态试验方法得到,而瞬态试验方法显然较前者更接近实际火灾情况。本文利用MTS810试验系统对1mmG550冷成型钢进行了详细高温瞬态试验研究,并将试验结果与已完成的同批次G550冷成型钢高温稳态试验进行了细致对比,结果表明:①G550冷成型钢瞬态试验极限强度折减系数在525℃以下时与稳态试验结果比较接近,但在550℃以上时明显高于稳态试验结果;②相同温度、应力水平下,G550冷成型钢瞬态试验应变值高于稳态试验结果,尤其在应力-应变曲线非弹性段二者差异明显。因此,瞬态试验方法与稳态试验方法对G550冷成型钢并不等效。然后,基于统计平均方法得到瞬态试验高温弹性模量以及屈服强度,同样与稳态试验结果进行了比较;最后,通过数值拟合提出了G550冷成钢高温材性折减系数及本构关系表达式,表达式与试验结果基本吻合,满足工程精度要求。

G550高强度冷成型钢高温力学性能稳态试验研究

冷成型钢高温材料特性是进行冷成型钢结构抗火设计及数值模拟的基本参数。现有的冷成型钢高温材性试验可能限于试验设备条件及材料差异等原因导致结果差异明显,不够理想。本文利用MTS810试验系统对1mmG550冷成型钢平板及转角部位进行详细的高温稳态试验研究。将G550冷成型钢平板与转角部位试验结果进行细致对比,表明:G550冷成型钢转角冷弯效应在常温下可能引起不利影响;高温情况下,转角部位材性折减系数普遍低于平板部位,可能导致冷成型钢构件提早发生高温局部、畸变屈曲。将G550冷成型钢弹性模量、屈服强度、极限强度折减系数与现行欧洲规范、澳大利亚规范、英国规范及其他学者的试验结果进行比较,并采用统一表达式进行数值拟合。拟合公式与试验结果符合良好,满足工程精度要求。基于Ramberg-Osgood模型,提出G550冷成型钢高温本构关系表达式,表达式与试验曲线吻合良好,满足冷成型钢数值模拟要求。

高钛焊丝钢ER70S-G冶炼工艺优化实践

高钛焊丝钢ER70S-G研发时经常出现水口结瘤、结晶器“结鱼”、铸坯夹渣等问题,尤其是铸坯夹渣导致轧制后盘条表面出现连续性锯齿状结疤缺陷,严重影响盘条表面质量。引起水口结瘤、结晶器“结鱼”的主要原因是存在TiO_(x)、TiN等高熔点非金属夹杂物。通过控制钢水中氧氮含量、使用纯净合金、降低渣中SiO_(2)活度、调整钛合金化时机及温度等手段,解决了水口结瘤、结晶器“结鱼”、铸坯夹渣等问题,将高钛焊丝钢ER70S-G连浇炉数提高至10炉,盘条成材率提高至97%,优化效果显著。

Electrolytic surface hardening of steel, cast iron and aluminium-bronze

Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel, cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

Effects of Strain Ratio on Fatigue Behavior of G20Mn5QT Cast Steel

Due to traffic and wave actions, cast steel joints are subjected to variable-amplitude fatigue loading, which may cause fatigue problems. The ratio of the minimum strain to the maximum strain(strain ratio)can be employed to analyze the influence of variable-amplitude fatigue both in the elastic and plastic ranges. To evaluate the effect of the strain ratio on G20Mn5 QT cast steel, the fatigue tests of smooth specimens were carried out at the strain ratio of 0.1. The cyclic deformation and the relationships between the strain amplitude, the stress amplitude, the Smith, Watson and Topper(SWT)parameter and fatigue life were studied and compared with those at the strain ratio of-1. Compared with other methods, Basquin formula and Solonberg formula provide reliable and appropriate ranges of S-N curve and fatigue limit at different strain ratios respectively. The SWT parameter can be used to predict the fatigue life at other strain ratios accurately.

Effect of CO_2 on Atmospheric Corrosion of UNS G10190 Steel under Thin Electrolyte Film

The atmospheric corrosion of UNS G10190 steel under a thin electrolyte film in the atmosphere polluted by CO_2, has been studied in the lab using an atmospheric corrosion monitor (ACM) in combination with XRD and SEM observations of the surface of steel. The ACM study indicated that the corrosion rate of the steel increased with increasing carbon dioxide concentration. The XRD and SEM observations showed that no carbonate was found in the corrosion product on the steel surface. The corrosion product consisted of two layers, i. e., inner and outer layer. From the experimental results, it was concluded that CO_2 played an enhancing role in the atmospheric corrosion of UNS G10190 steel. The film of the corrosion product showed slight protection.

Relationship between the Brittlement Susceptibility and H Permeation Current for UNS G11180 Steel in 5% NaCl Solution with H_2S

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydro gen permeation technique. The results reveal different cracking mechanism and H permeation current (IH) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 Steel in 5% NaCl solution with H2S was evaluated by the permeation current(IH, μA), which depends on the concentration (c×10-6) of H2S by the equation:IH = 8.525 ×c0.7249. lt is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

Seismic responses of the steel-strip reinforced soil retaining wall with full-height rigid facing from shaking table test

To investigate the seismic response of the steel-strip reinforced soil retaining wall with fullheight rigid facing in terms of the acceleration in the backfill, dynamic earth pressure in the backfill, the displacements on the facing and the dynamic reinforcement strain distribution under different peak acceleration, a large 1-g shaking table test was performed on a reduced-scale reinforced-earth retaining wall model. It was observed that the acceleration response in non-strip region is greater than that in potential fracture region which is similar with the stability region under small earthquake,while the acceleration response in potential fracture region is greater than that in stability region in middle-upper of the wall under moderately strong earthquakes. The potential failure model of the rigid wall is rotating around the wall toe. It also was discovered that the Fourier spectra produced by the inputting white noises after seismic wave presents double peaks, rather than original single peak, and the frequency of the second peak trends to increase with increasing the PGA(peak ground amplitude) of the excitation which is greater than 0.4 g. Additionally,the non-liner distribution of strip strain along the strips was observed, and the distribution trend was not constant in different row. Soil pressure peak value in stability region is larger than that in potential fracture region. The wall was effective under 0.1 g-0.3 g seismic wave according to the analyses of the facing displacement and relative density. Also, it was discovered that the potential failure surface is corresponds to that in design code, but the area is larger. The results from the study can provide guidance for a more rational design of reinforced earth retaining walls with full-height rigid facing in the earthquake zone.

河北钢铁邯钢开发出澳标高强镀锌板G550

近日,河北钢铁集团邯钢公司成功开发出澳标高强结构用镀锌板G550。该产品属于高强系列镀锌板,抗拉强度、屈服强度要求很高,屈服强度最低为560MPa,抗拉强度最低为650MPa,伸长率不小于2%,锌层厚度要求为275g/m^2,具有较强的抗腐蚀性,应用于Z型钢、C型钢、楼层板等领域。

民用飞机参考机种之一 “湾流”G500/G550远程双发涡扇公务机

“湾流”GS00／G550飞机是美国湾流航宇公司在“湾流”V公务机的基础上，改进研制的远程双发涡扇公务机。机翼（包括机翼上的操纵面）由沃特飞机工业公司和日本新明和工业公司负责设计和制造：荷兰斯托克航宇集团负责制造尾翼和后部地板：发动机由英国罗耳斯·罗伊斯德国公司提供：驾驶舱航电系统由霍尼韦尔国际公司安排。

Matrox宣布全新Millennium G550半高度PCIe图形卡

专用的图形方案生产商Matrox Graphics Inc．日前宣布推出Matrox Millennium G550半高度PCIe．世上首张半高度PCI Exptess ×1图形卡，把先进的双头显示功能带给金融．保险，法律和各类使用多显示的公司市场。Matrox Millennium G550 PCIe的架构为×1的设计，合符所有PCI Express（×1,×4,×8和×16）规格插槽，

iOS 7新“掌机” 罗技G550与MOGA ACE POWER

对于iPhone用户来说，在触摸屏幕上使用虚拟摇杆来操控游戏是很苦恼的，为了带领玩家们逃脱苦海，iOS7具备了一个新特II生．就是对第三方游戏手柄的支持。近期．罗技（Logitech）和MOGA两大厂商都推出了相应的游戏手柄，罗技G550和MOGAACEPOWER，一起来听听两位米饭对这两款新“掌机”作何评判吧!

手柄？护套？手游控必备!——罗技G550掌游控手机游戏手柄

作为手游爱好者，每天最快乐的时光就是下班之后躺在床上，拿起手机玩玩自己喜欢的游戏。不过，随着游戏越玩越多，笔者突然发现了一些问题，那就是手游的操作很别扭。休闲手游没有什么操控性，可以不论，但那些体育竞技类和格斗类等对操作要求比较高的手游，用屏幕上的虚拟按键玩起来那叫一个坑爹。还好，笔者最近入手了罗技的G550掌游控手机游戏手柄（以下简称G550），彻底解决了这个烦恼。

速度并不是一切──Millennium Matrox G550测评

由于种种原因，大家翘首以盼的Ｇ８００并没有如期推出。Ｍａｔｒｏｘ改变了原有的计划，将这款Ｇ５５０作为目前的主打产品。对于３Ｄ游戏玩家而言，一块好的显示卡有几个要素：极高的象素填充率、配有快速高容量的显存和尽可能支持最多的３Ｄ功能。Ｇ５５０并不具备这些要素。但是，Ｍａｔｒｏｘ凭借其业界最出色的２Ｄ显卡，在当今竞争异常激烈的显卡市场中依然屹立不倒。几乎所有大的ＯＥＭ厂商，包括戴尔、惠普、康柏、富士通等，所生产的高端工作站都已采用Ｇ５５０双头显卡作为它们的标准配置。最近ＡＴＩ Ｒａｄｅｏｎ ＶＥ和ｎＶＩＤＩＡＧｅｆｏｒｃｅＺ ＭＸ双头显卡闯进Ｔ Ｍａｔｒｏｘ一直占领的这块净土，但从目前的情况看来，此举并未动摇Ｍａ ｔ ｒｏｘ在各大ＯＥＭ厂商。ｕ目中的地位。那么８ｉｌｌｅｎｎｉｕｍ Ｍａｔｒｏｘ Ｇ５５０ｆ４底有什么魁力呢，还是让我们来仔细品味一下吧。