Quality of thick steel sheet for spiral-seam electrowelded pipe of strength class K60 (X70)

The mechanical properties, microstructure, fractures, and texture of a trial industrial batch of 07Г2MФБ steel sheet (thickness 21.7 mm) for the manufacture of spiral-seam gas-line pipe (diameter 1420 mm) of strength class X70 at OAO Volzhskii Trubnyi Zavod (VTZ) are investigated. It is shown that the selected chemical composition of the steel and thermomechanical rolling technology yield mechanical properties of the sheet and the basic pipe metal complying with VTZ specifications.     

成品厚度对无取向硅钢织构和磁性能的影响

研究了成品板厚度(0.35～0.65 mm)对0.003%C-2.40%Si-0.32%Al无取向硅钢织构演变、磁感和铁损的影响。结果表明,随着钢板厚度的减薄,成品中对磁性不利的织构组分增加,有利织构组分减少,磁感降低。在化学成分和晶粒尺寸一定的情况下,影响铁损的主要因素是钢板厚度,钢板厚度从0.65 mm减薄至0.35 mm时,铁损显著降低。     

汽车结构用550MPa级热连轧钢板的研制开发

介绍了汽车结构用热连轧钢板QStE550TM的试制情况,包括化学成分、冶炼工艺及热连轧工艺设计思路,同时针对产品组织、力学性能和工艺性能等进行了检测分析。试验结果表明,采用低碳、复合添加钛铌微合金化和控轧控冷技术,能够成功开发出厚度为3.0~16.0 mm的低成本高强度汽车结构钢。该钢具有较高的强度、良好的低温冲击韧性和宽冷弯性能等,可以广泛地用于重载汽车的横、纵梁和底盘零件的制造。     

冷轧DC04平整工艺试验研究

文章介绍了通过采用77％。82％的冷轧变形量,将原料轧制到0．7-0．8mm厚的Ti—IF钢板采用不同的轧制力进行平整的试验。结果显示相关机械性能随着平整力增加而变差,为保证带钢的性能,选择采用较小平整轧制力进行生产。     

Thick-walled centrifugally cast 08X18H10T steel blank for seamless-pipe production

Thick-walled pipe blanks made by centrifugal casting of corrosion-resistant 08X18H10T steel are investigated. These blanks are intended for subsequent hot pressing of pipe (diameter 89 mm, wall thickness 12 mm). The macrostructure of the castings is studied, as well as the mechanical properties of cast and heat-treated tangential, transverse, and longitudinal samples. The defects observed in the centrifugally cast pipe are analyzed. The resistance of the cast metal to deformation is assessed, as well as the technological plasticity of the cast pipe blank.     

Deep Drawing of Friction Stir Welded Thin Sheet Aluminium Steel Tailored Hybrids

Friction stir welding undergoes a steep evolution in industrial applications since the invention in the early 1990s. Especially for aluminium alloys in sheet thicknesses over 2 mm a lot of applications are established, whereas a lack in knowledge about friction stir welding of thin sheets with sheet thickness less than 2 mm exists. This article deals with friction stir welding of thin sheet aluminium steel tailored hybrids and their formability. These investigations tend to close the gap of availability of friction stir welded blanks in the range of 1 mm sheet thickness and to offer new applications of this joining technology. For production of aluminium steel tailored hybrids AA5182 with a thickness of 1.2 mm and DC04 in 1.0 mm are used, the joining partners are friction stir welded in a lap joint. Different tool geometries and process parameters are performed to achieve the highest strength and elongation at fracture of the tailored hybrids. The influence of the stirring on the arrangement and distribution of both materials in the welding zone and its microstructure is analysed using light optical and scanning electron microscopy. In addition to tensile tests planar microhardness measurements help to detect the local changes of the mechanical properties in the characteristic zones of the weld seam. Tailored hybrids, which were friction stir welded with the best welding parameters in accordance to the mechanical properties of the weld seams, were used for deep drawing tests of friction stir welded thin sheet aluminium steel tailored hybrids. The maximum drawing ratio of these tailored hybrids coincides with the one of the parent material of AA5182.     

Ti-IF冷轧深冲钢平整工艺研究

对77.5%冷轧变形量、0.9 mm板厚的Ti-IF钢板采用不同的轧制力进行平整。研究不同平整力下的晶粒度和力学性能的变化。     

Production of pipe blanks from corrosion-resistant duplex steel

The introduction of pipe-blank production (blank diameter 180 mm) from corrosion-resistant duplex steel (UNS S 31803, UNS S 32205, DIN 1.4462, and 03X22H5AM3) at PAO Dneprospetsstal’ plant is considered. The chemical composition of the melts at PAO Dneprospetsstal’ and pipe blank produced from duplex at traditional foreign suppliers is compared. The content of nonmetallic inclusions is studied, as well as the distribution and content of ferrite-austenite phases, the impact strength, the resistance to pitting corrosion, and the high-temperature deformability.     

Failure of large-diameter steel pipe with rolling scabs

Russian pipelines employ large-diameter pipe of straight-seam, two-seam, and spiral-seam type (diameter up to 1420 mm, API strength class up to K65). The newest developments in the production of large-diameter (1020, 1220, and 1420 mm) straight-seam welded pipe (strength classes K38–K65 and X42–X80, wall thickness up to 52 mm, length up to 18 mm, and working pressure up to 22.15 MPa) is stepwise press shaping (the JCOE process), proposed by SMS Meer (Germany). The SMS Meer technology is widely used at Russian pipe plants (AO Vyksunskii Metallurgicheskii Zavod, AO Izhorskii Trubnyi Zavod, PAO Chelyabinskii Truboprokatnyi Zavod) and also plants in Russia, China, and India. However, the accident statistics for Russian pipelines show that stress corrosion of the pipe wall mainly occurs in pipelines of large diameter (700–1420 mm). More than 80% of pipeline failures associated with stress corrosion occur in pipelines of diameter 1020–1420 mm. Corrosion cracking of pipe walls may be attributed to three main factors: (1) poor steel quality and pipe defects in manufacturing (such as high residual stress, microcracks and micropeeling of the metal after shaping of the pipe blank, corrugation, scratches, scabs from the rolling process, and imperfections of the weld seams); (2) the presence of a corrosive medium and its access to the metal surface; (3) multicyclic fatigue and failure of the metal on account of pulsation of the working pressure within the pipe and hydraulic shocks. In Russian oil pipelines, failures due to production defects and assembly and installation problems are twice as frequent as in the United States and Europe. Therefore, careful study of pipeline failure due to production flaws is of great importance. In the present work, a mathematical approach is proposed to determining the critical pressure in the pipe at which elastoplastic failure of the pipe will occur at rolling scabs accompanied by a scratch on the pipe’s outer surface. The results may be used in failure diagnostics of large-and medium-diameter steel pipe for major delivery pipelines and transfer pipelines.     

S32760超级双相不锈钢冷轧板的组织和性能

设计及制备了2mm厚S32760超级双相不锈钢冷轧板。对国产及进口冷轧板的化学成分、常温力学性能、金相组织、杯突值、应变硬化指数、腐蚀性能及焊接性能进行了对比测试。结果表明,国产板材各项性能指标达到ASEMSA240标准及工程指标要求,与进口板材相当,可以替代进口产品用于相关设备的生产及制造。     

Mechanical and fatigue properties of self-piercing riveted j oints in high-strength steel and aluminium alloy

Static tensile and fatigue tests were performed on shear and tensile self-piercing riveted aluminium-steel structures to evaluate their mechanical and fatigue properties.The influences of the thickness and the strength of the high-strength steel on mechanical and fatigue performances were investigated based on the tensile and F-N curves of the joints.The results show that mechanical and fatigue properties of the shear self-piercing riveted joints are much better than those of the tensile self-piercing riveted joints.Mechanical and fatigue performances of the two joints were significantly influenced by the thickness and strength of the steel sheet, and were markedly improved when the thickness of steel sheet increased.The steel strength showed significantly different effects on shear and tensile riveted structures, i.e., when the steel strength increased, the strength of the shear structure greatly increased while the tensile structure just had a slight increase in the strength.Fatigue failure generally occurred in the sheet materials and the fa-tigue crack location changed with increasing the sheet thickness and the sheet strength.     

Simulation of the shaping of blanks for large-diameter pipe

An analytical method is outlined for calculating the bending parameters of thick sheet (thickness up to 40 mm) used in pipe production: the size and shape of the punch-blank contact zone; the elasticity coefficient of the blank and its residual surface curvature; the maximum force of the punch at different stages of stepwise shaping on a press. At all stages of the process, the model of an elastoplastic medium is employed. The results may be used in developing production technologies for large-diameter steel pipe used in pipelines.     

Q235/5083异种材料自冲铆接头力学性能的研究

通过异种材料Q235钢板和5083铝板进行自冲铆接,分别研究了组合方式、板厚、接头热处理（模拟车身烘烤过程）等工艺因素对接头力学性能的影响,结果表明:5083铝板作为下板时接头的性能更优,并且Q235上板板厚对接头的性能有一定的优化作用.在该实验中,接头b#的组合方式是较优的工艺参数,即1.5 mm Q235-2.0 mm5083;经过烘烤后接头的失效载荷和失效位移都有不同程度的增加,其中性能较优的接头b#经烘烤后失效载荷提升了5.80 %,失效位移提升了8.26 %;汽车车身涂装过程中进行烘烤作业对接头的性能不会造成强度损失,相反还会对接头力学性能和稳定性有一定程度的优化作用.      

Structuring and deposition of nanoparticles in X70 steel during coiling and subsequent cooling

The influence of strip winding on the structure formation and microalloying of X70 steel with added Ni, Cu, and Mo is investigated. Decrease in winding temperature increases the content of transformation products of nonpolygonal morphology. The temperature conditions in which nanoparticles (3–8 nm) of Nb and V carbonitrides are formed in the steel after winding are established. At OAO Severstal, tests have been conducted on the production of X70 steel strip (thickness 14–16 mm) with uniform mechanical properties. It is found that sheet of measured length may be supplied.     

00Cr18Ni10N钢管冷作硬化工艺探索

为了使00Cr18Ni10N冷作硬化态钢管的力学性能达到标准要求,在成品Φ15mm的钢管生产上对原始组织状态(退火和不退火)、冷拔变形量、退火温度等影响冷硬态钢管力学性能的因素进行试验摸索,并初步摸清了退火温度以及变形量等参数对性能的影响。并最终确定了退火温度以及冷拔变形量,即对荒管进行1060℃退火处理,冷拔变形量7%～10%就可以达到较好的强度和塑性,生产出达到标准要求的冷硬态管材。     

Effect of Thin Polymer Coatings on the Mechanical Properties of Steel Plates

The influence of powder coatings based on an epoxide polyester mixture on the mechanical properties of the plates made of rolled sheet steel is studied. The influence of 100-μm-thick coatings on the mechanical properties of specimens 0.7–1.5 mm thick is considered. The bending and tensile tests performed at room and elevated temperatures show that the thin coatings weakly affect the mechanical properties of the plates. In particular, the stiffness of the coated plates during tension and bending remains almost the same despite the fact that the elastic modulus of the coated plates is always slightly lower than Young’s modulus of steel because of an increased specimen thickness determined with allowance for the presence of a coating. The influence of the coatings is substantial in compressive stability tests. Under supercritical deformation conditions, the bearing capacity of the coated plates decreases substantially, and their critical stability load on the loss of stability falls by 20–30% (depending on the substrate thickness). This effect can be explained by the influence of the residual thermal stresses that appear in the specimens during coating deposition.     

Geometry of steel sheet in a seven-roller straightening machine

A method of determining the parameters of preliminary cold straightening of steel sheet on a seven-roller machine is proposed. The calculations permit the determination of the shape and curvature of the sheet’s central plane during and after straightening, as a function of the radius and spacing of the rollers, the reduction of the sheet by the upper rollers, the sheet thickness, and also the Young’s modulus, yield point, and hardening modulus of the steel. The results may be used at steel plants in the production of broad sheet and thick-walled pipe for pipelines.     

50W1300冷轧无取向电工钢带的工业试制

采用40 t氧气顶吹转炉-180 mm×495 mm板坯连铸-连轧工艺流程,试制了0.5 mm×480 mm 3 t 50W1300冷轧电工钢带(铸坯成分%:0.04～0.06C、0.82～0.96Si、0.35～0.40Mn、0.015～0.017P、0.014～0.019S)。通过钢包吹氩,控制钢水终点温度1650～1670℃,钢中氧含量由72.9×10^-6降至22.9×10^-6。试制的冷轧无取向电工钢带成品的电磁性能和力学性能均达到GB/T2521-1996中50W1300标准要求,适用于小型电动机转子的制造。     

Fe-6.5%Si钢极薄带的试制

 为了研究Fe-6.5%Si钢极薄带的制备工艺,并获得良好的产品磁性能,以薄带铸轧试验机制备的6.5%Si钢铸带为原料,分别采用一次温轧法、二次温轧法和基于应变诱导无序(DID)原理的高硅钢室温冷轧3种工艺制备出厚度为0.1 mm的Fe-6.5%Si钢。分析结果显示,一次温轧法退火后以高强度γ织构为主,由于压下率达到90%,形变储能高,晶粒尺寸最大,铁损最低,同时磁感也最低;二次温轧的退火板除了γ织构外,还有较强的η织构,故其磁感值高于一次温轧法,该方法得到的6.5%Si钢薄带综合磁性能最优,但生产成本高,效率低;基于DID原理,对6.5%Si钢热轧板在温度为300～450 ℃、压下率为45%～65%的条件下进行温轧,实现了6.5%Si钢软化,随后可将6.5%Si钢室温冷轧至0.1 mm,此时温轧板和冷轧板内部有序相消失,基体变成无序态;室温冷轧板退火后晶粒更细,铁损略有升高。此外,室温冷轧可促进{111}<112>形变晶粒在冷轧剪切带中形核形成有利织构,因此磁感值得到更大提升;采用DID原理进行室温冷轧,效率较高,后续可通过优化退火工艺使其进一步降低铁损,该方法为薄带铸轧工艺批量生产磁性能优异的6.5%Si钢极薄带提供技术参考。     

冷轧变形率对超纯铁素体不锈钢Cr22Mo织构和成形性能的影响

试验研究的Cr22Mo钢(/%:0.005C,0.40Si,0.20Mn,0.020P,0.010S,22.0Cr,1.0Mo,0.41Cu,0.14Nb,0.19Ti,0.0120N)经90 t BOF-VOD-LF-200 mm板坯连铸-热轧成5.0 mm板-退火并冷轧成1.5～0.5 mm板,冷轧变形率为70%～90%,冷轧板经1000℃退火。利用光学显微镜、X-射线衍射仪(XRD)和万能拉伸试验机研究了冷轧变形率对Cr22Mo钢组织、织构和力学性能的影响。结果显示,随着冷轧变形率的增大,冷轧和冷轧退火板的组织细化,再结晶织构{111}<112>强度增加,平均塑性应变比(r)值增加,平面各向异性△r值降低,冷轧压下率的增大显著改善了Cr22Mo钢冷轧退火薄板的成形性能。