Evolution of MnS and MgO·Al_(2)O_(3) inclusions in AISI M35 steel during electroslag remelting

Thermodynamics and kinetics of dissociation and precipitation of MnS inclusions,as well as the effect of reoxidation in liquid steel on MgO·Al_(2)O_(3)inclusions in AISI M35 steel during electroslag remelting(ESR)process were investigated.The inclusions found in the consumable electrode were MnS,MgO·Al_(2)O_(3)and MnS adhering to MgO·Al_(2)O_(3).MnS inclusions were nearly spherical and ellipse in morphology,and most of them were less than 2μm in size.MgO·Al_(2)O_(3)inclusions were polygonal and nearly spherical and most about 1-4μm in size.The inclusions in ESR ingot observed by scanning electron microscopy-energy-dispersive X-ray spectrometer were polygonal and nearly spherical MgO·Al_(2)O_(3).MnS inclusions in the consumable electrode were completely dissociated before the liquid film dripping into molten slag pool.The controlling step of MnS inclusions dissociation was the mass transfer of[Mn]in the liquid steel.During the solidification process,the thermodynamic driving force could not meet MnS inclusions precipitation before the solid fraction exceeds 0.996,and the kinetics condition is too poor for the growth of MnS inclusions in the steel when the solid fraction is larger than 0.996.MgO·Al_(2)O_(3)inclusions in ESR ingot originated from the remained MgO·Al_(2)O_(3)inclusions in consumable electrode and the fresh ones formed by the reaction between dissolved magnesium,oxygen and aluminum in liquid steel.

Flow behaviour constitutive model of CuCrZr alloy and 35CrMo steel based on dynamic recrystallization softening effect under elevated temperature

In order to study the effect of dynamic recrystallization on the metal flow behavior during thermal deformation,the elevated temperature compression experiments of CuCrZr alloy and 35CrMo steel are carried out using Gleeble-3810 thermal simulator.It is proved that the samples underwent obvious dynamic recrystallization behavior during thermal deformation by microstructure observation of deformed specimens.The size of recrystallized grains increases as the temperature improved and the strain rate decreased.Meanwhile,the net softening rate caused by dynamic recrystallization is determined based on the stress-dislocation relationship.It can be found that the value of net softening rate increases quadratically as the Z parameter decreases,and the dynamic recrystallization net softening rate of CuCrZr alloy and 35CrMo steel are calculated to be 21.9%and 29.8%,respectively.Based on the dynamic recrystallization softening effect proposed,the novel elevated temperature flow constitutive models of two different alloys are proposed,and the related parameters are well defined and solved in detail.The predicted values of the obtained models are agreed well with the experimental values.

SIMULATED RESEARCH ON HOT FORMING MECHANISM OF 35CrMo STEEL

The significance of this paper lies in the application of bending-upsetting 35CrMo steel in train crack-shaft. The hot deforming tests of 35CrMo steel have been done on the Gleeble-1500 testing machine with the deformation temperature at the range of 900癈-1250癈, a strain strain of 0.05 s-1, 0.5 s-1, 1.0 s-1 and compress degree of 15%-80%. Through respectively analyzing and studying the microstructure of the specimen and getting the data from the testing, the results obtained are as follows: the model of flow stress and the stress-strain relationship of material hot deformation, the model of dynamic and static re-crystallization and the correlative references of hot forming parameters and changes of microstructure. The hot deforming stress-strain curses and relevantly re-crystallized micro-structure of 35CrMo steel are drawn at the deformation temperature of 1250 and the strain rate of 1.0 s. Through analyzing and regressive calculating the grain size of the deformation specimen of 35CrMo steel at different locations under the large-deformation and high-temperature conditions, the hot-deforming model of grain calculation is verified. The experimental results and the model of grain calculation can provide scientific basis for analyzing the hot deformation processes and controlling quality.

35 T敞顶箱专用卷钢座架静态荷载强度检测及冲击试验

以35 T敞顶箱为例,在通过soildworks机械设计软件对CRTZJ01型卷钢座架进行造型并对其受力进行理论分析的基础上,进行卷钢座架的静态荷载强度检测和冲击荷载试验研究。试验结果表明:试验前后座架整体状态完好,试验后未发现任何肉眼可见的座架变形、焊缝开焊、座架破损损伤等情况,座架相对于车体无明显位移,因此,35T敞顶箱专用卷钢座架满足卷钢铁路安全运输的要求。

35钢粘附特性研究

应用回归设计技术,探讨了35钢与土壤粘附特性及其影响因素。研究表明:热处理工艺能改变试样的粘附特性;在硬度较高或存在游离铁素体的条件下,硬度对粘附力的影响不同;金属材料与液体间的固—液接触角是影响粘附力的较主要因素;铁素体双相组织能降低粘附力值。

35钢在模拟酸雨溶液中的腐蚀行为

35钢在城市交通工程中应用越来越多,酸雨对其腐蚀严重,过去对其研究不多。为此,配制了模拟酸雨溶液,研究了35钢在模拟酸雨溶液中的腐蚀行为,探讨了酸雨酸度和浸泡时间对35钢腐蚀行为的影响。采用极化曲线、电化学交流阻抗(EIS)及扫描电镜(SEM)方法对35钢的腐蚀进行了测试分析。结果表明:随着模拟酸雨溶液pH值的降低,35钢的腐蚀电流逐渐增大,腐蚀速率增大,腐蚀电位负移;随着浸泡周期的延长,阻抗谱中锈层阻抗增大,腐蚀速率降低,表面生成的腐蚀锈层对基体起到一定的保护作用。SEM和EDS分析表明,35钢在低pH值的酸雨中腐蚀严重,表面蚀坑密集且深,腐蚀产物粗大疏松,致密性差,为硫酸盐,而pH值升高时腐蚀相对较轻,蚀坑较小。

海水中阴极保护35钢有限元模拟研究

设计了海水中铝基牺牲阳极阴极保护35钢的电极电位分别处于保护范围内、过保护、欠保护状态下的物理模型,推导Laplace方程的弱形式,方便了有限元程序设计。利用Kriging网格化插值法比较了有限元计算和实验数据。结果表明,有限元法模拟计算三种保护状态下的电位分布接近测量值。

钻杆接头材料35CrMo钢硫氮共渗层的摩擦学性能

为了提高钻杆接头的使用寿命,利用离子渗氮和硫氮共渗技术在钻杆接头材料35CrMo钢表面制备了氮化层和硫氮共渗层。在油润滑条件下采用自制的球-盘磨损试验机考察了表面渗层的摩擦磨损性能。利用了XRD研究了表面层的相结构,采用了带EDS的SEM对表面改性层和磨损表面进行了分析。结果表明:35CrMo钢硫氮共渗层的摩擦学性能明显优于原始渗氮层;具有优良润滑作用的FeS固体润滑膜在高硬度氮化层的支撑下,可以有效地改善钻杆接头的摩擦磨损性能。

GT35钢结硬质合金应用技术研究

研究了GT 35钢结硬质合金大坯料的锻造、热处理与切削加工等应用工艺技术 ,并提供了一系列工艺参数。这些研究结果将为进一步研究和推广应用该材料提供了重要的参考依据。

35钢表面增压喷丸纳米化对气体软氮化的影响

通过表面增压喷丸处理,在35钢表面形成了厚40μm的纳米晶层,对具有纳米晶层的试样进行气体软氮化。采用透射电镜﹑扫描电镜﹑X射线衍射仪等对35钢表面纳米晶组织及其软氮化渗层组织进行了观察与分析,并测试了渗层硬度。结果表明:经过增压喷丸处理的试样,化合物层厚度大约为原始试样的2倍,软氮化时间可由10 h缩短为3 h;渗层硬度也有明显的提高。

35钢牺牲阳极性能及其对铜管阴极保护的可行性

采用恒电流试验测试了35钢在海水和淡水中的牺牲阳极性能,并结合紫铜的极化曲线测试和阴极保护试验分析了35钢用于铜管牺牲阳极保护的可行性。结果表明:35钢在海水和淡水中都具有良好的牺牲阳极性能,工作电位稳定,电流效率高,溶解均匀,消耗慢;对紫铜管进行阴极保护有足够的驱动电压,达200 mV以上;短期阴极保护试验结果显示35钢对紫铜管有良好的保护效果。

ZG15CrMoV和35钢在500—1400℃下的流变行为

本文以Gleeble-1500为实验手段,研究了ZG15CrMoV和35钢在500—1400℃温度范围内的力学行为,结果表明,两种钢在高温下表现出越来越强的时变特征,应用系统辨识理论,以实验数据作为系统的输入—输出响应,确立了两种钢在高温下的力学行为可以较好地由一个五元件流变模型[M]=[H_1]—[H_2/N_2]-[N_3/S]予以描述,通过研制的流变模型和参数辨识软件,对ZG15CrMoV和35钢在上述温度范围内的流变参数进行了辨识,辨识结果与实验结果均能较好的吻合。

稀土La对35钢盐浴碳氮共渗涂层结构与性能的影响

在由氰酸盐(KCNO和NaCNO)与碳酸盐(K2CO3和Na2CO3)组成的盐浴中添加适量稀土La,对35钢材料进行盐浴碳氮共渗,对涂层的显微组织、涂层的厚度、显微硬度沿层深的分布以及涂层的耐磨性进行测试与分析,研究稀土La对35钢盐浴碳氮共渗的影响。结果表明:在盐浴中添加稀土La可显著提高碳氮共渗层的厚度和表面硬度;在温度为560℃、时间为2 h条件下进行盐浴碳氮共渗时,添加稀土La可增加化合物层的厚度,稀土添加量(质量分数)为5%时化合物层最厚;添加稀土还可提高涂层硬度,在575℃/2 h、添加5%稀土条件下盐浴碳氮共渗后,试样表层硬度HV0.01达到最大值835,且耐磨性显著提高,与常规盐浴碳氮共渗相比,质量磨损降低38.4%。

QPQ处理对35钢组织性能的影响

选用35钢作为研究材料，进行不同工艺条件的QPQ盐浴复合处理，研究氮化温度（530~575℃）和氮化时间（3-5h）对35钢组织及表面性能的影响。结果表明，35钢在QPQ处理后表面由外到内可形成明显的白亮层和扩散层，且渗层厚度随氮化温度升高和氮化时间的延长而增大。

35MnVN、40MnVTi非调质钢温锻后的组织及耐磨性研究

研究了35MnVN、40MnVTi非调质钢和45、40Cr调质钢经650℃温锻后的显微组织及耐磨性,分析了磨痕形貌。结果表明,在90kg负荷下的滑动摩擦磨损特性试验中,35MnVN钢的耐磨性与40Cr钢相当,40MnVTi钢稍差,45钢最次。

27SiMn钢与35钢焊接工艺

液压缸筒由低合金27Si Mn和35钢焊装,由于是异种钢焊接,其焊缝及热影响区容易出现高硬度、高脆性、韧性较低的组织和性能,而焊接是油缸生产制造过程中关键工序之一。选用CO2气体保护焊,精选低氢低碳合金焊材和焊接工艺参数,采用焊前预热、焊后缓冷的焊接工艺。经焊后力学性能试验,各项指标合格;经焊接工艺评定,焊缝成形好,焊缝热影响区小,焊接变形小,无气孔、无裂纹、无未熔合、无未焊透等缺陷,焊接质量优良。结果表明,采用合理的焊接工艺,低合金钢27Si Mn与35钢焊接性能优良,能满足液压油缸的工作要求。

35钢渗碳淬火管件的裂纹失效分析

通过XRD物相分析、显微组织观察以及显微硬度测试、分析了35钢管件开裂的原因,并提出了改进措施。结果表明,管件中存在带状夹杂物,热处理过程导致夹杂物周围形成应力集中,回火温度不充分致使组织脆性大,集中应力释放引起开裂。

QPQ盐浴复合处理对35钢组织和性能的影响

对35钢进行QPQ盐浴氮化复合处理,运用X射线衍射(XRD)和金相显微镜(OM)对处理后的样品进行相结构和组织形貌分析,另外还对处理前、后的35钢分别进行了显微硬度测试、极化曲线测试以及滑动磨损性能实验。结果表明:经过QPQ处理后的35钢表面生成了一层铁的氮化物和氧化物,其相应的耐磨性能和耐腐蚀性能都有了很大提高。

35钢在形变作用下产生超平衡铁素体的研究

利用单道次热模拟压缩试验研究了35钢在形变等温过程中铁素体组织的变化规律。结果表明,等温过程中形变诱导铁素体体积分数呈先减少后增加的趋势,即在形变后等温的弛豫过程中,不稳定的形变诱导铁素体发生了逆相变。等温温度越低,等温后的弛豫过程越明显,铁素体转变量越多。随着等温时间的延长,γ→α相变速度将远快于形变诱导铁素体相变的逆相变,形成了多于平衡状态的铁素体体积分数。

常规奥氏体化后后续热处理对35CrNi3MoV钢组织与性能的影响

通过硬度测试、室温拉伸实验、低温冲击实验研究了常规奥氏体化后后续热处理对35Cr Ni3Mo V钢的组织与性能的影响。结果表明:相比常规奥氏体化淬火,经常规奥氏体化淬火+回火热处理工艺处理(860℃×6 h+810℃×2 h,油冷淬火+600℃×16 h,油冷回火)后,锻件的低温冲击韧性提高了约33%,硬度为326 HB,室温拉伸强度略微下降,伸长率提高了约3.65%;在常规奥氏体化淬火+回火热处理工艺下(860℃×6 h+780℃×2 h,油冷淬火+600℃×16 h,油冷回火),锻件的低温冲击韧性与常规奥氏体化淬火相比提升了约4.1%,室温拉伸强度和伸长率分别提升了约8.4%和9.62%,硬度为356 HB。在810℃低温奥氏体化淬火下,降低了锻件的强度并大幅度提高了室温冲击韧性,晶粒组织均匀且细小。在780℃亚温淬火下,大幅度提高锻件强度的同时也小幅度提高了室温冲击韧性。