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K. Toda H. Gondoh H. Takechi H. Masui 《Metallurgical and Materials Transactions A》1976,7(11):1629-1636
For high-strength steel sheets, a new concept has become necessary,viz, the relation between strength and formability. When the relation between tensile strength and elongation is appraised for
ranking in terms of the strengthening mechanism, it is found that the substitutional solid-solution hardening type is excellent
and the precipitation hardening type is inferior. In batch annealing, the phosphorus-added aluminum-killed steel sheets are
representative of the former type having excellent formability as indicated by a highr values despite their tensile strength of 450 N/mm2. The titanium-added aluminum-killed steel sheets, which are representative of the latter type, have a tensile strength of
600 N/mm2 and a relatively highr value. Continuous annealing of the highstrength steel sheets of the same chemical composition causes higher yield stresses
and combinations of yield stress and elongation. Alternatively with continuous annealing the same level of strength can be
achieved with smaller additions of alloying elements than with batch annealing. An additional advantage of continuous annealing
is the uniformity of properties along the length of the coil. The rapid cooling possible after continuous annealing allows
production of high strength steel sheets having excellent mechanical properties that are unobtainable in the batched annealed
steels. For example, steel sheets of 0.4 pet Si and 1.4 pet Mn after continuous annealing, haven values and Erichsen values as higher than conventional low-carbon rimmed or capped steel sheets even while they have a tensile
strengths of 550 N/mm2. 相似文献
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《Baosteel Technical Research》2010,(Z1):50
Shougang Group has carried out a strategic structure adjustment in order to realize the promise of Chinese people to the Olympic Games.Automotive sheets are chosen as a type of strategic product and an engine to upgrade enterprise management,technology and operation to reach the top international level during the transition from long products to steel sheets in Shougang Group.Since 2006,Shougang Group has made an elaborate preparation on steel sheet culture,production line construction,technology import,pilot plant and talent reserve.It lays the foundation for the development of automotive sheets.The developing history of cold rolled automotive sheets is reviewed and the research and development of cold rolled automotive sheets, tackling key problem of defect on surface and the latest progress of automotive sheets construction are described in this paper.The main contents were given as follows:①The products of automotive sheets realize zero breakthrough in Shougang Group.Monthly output was 300 ton in January,2009 and it increased to 48 000 ton in June,2010.The ratio of IF steel sheets increases to 70%from 40%.The proportion of outside panel in automotive sheets occupys more than 15%.②A high emulational pilot plant is used as a product developing platform to develop successfully automotive sheets with 1 000 MPa and below.It guarantees that the industrial development of DP and TRIP sheets gets success at a time.It covers continuous annealing sheets with tensile strength≤780 MPa and galvanizing sheets with tensile strength≤590 MPa.③Individual design is used to meet special requirement of customer.Shougang owns 23 inner brands of LCAK and IF steels.It insures that the grades of yield strength cover whole range from 120 to 270 MPa.It keeps the stabilization of steel performance by means of chemical composition control and high accuracy rolling technology.For example,the strength of soft steel fluctuates within±15 MPa.④The steel sheets with surface grade O5 are produced steadily by solving forming striation of IF steel,grain coarse on surface,edge curling skin and mountains - and - waters painting defects.⑤The safeguard mechanism on quality of products is improved steadily and the output of automotive sheets and outside panel increases greatly by building consistency quality management system、information - system and customer service system. 相似文献
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M. Hirao H. Fukuoka K. Fujisawa R. Murayama 《Metallurgical and Materials Transactions A》1989,20(11):2385-2392
An ultrasonic technique for evaluating the formability of cold-rolled steel sheets is developed. The technique is based on
the generalized dispersion relation, which correlates the velocity anisotropy of ultrasonic plate modes guided in the sheet
plane to the texture defined by orientation distribution coefficients. Electromagnetic acoustic transducers (EMAT’s), constructed
of permanent magnets and meander-line coils, allow the accurate and easy measurement of transit times of theS
o (fundamental symmetric) mode. The planar average of the transit times shows a close correlation with both the planar average
of plastic strain ratios (r value), obtained through tensile tests and the pole intensities, measured with the X-ray diffraction method. These favorable
comparisons with the destructive tests indicate a good possibility of texture monitoring with the noncontacting EMAT’s. 相似文献
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ZHU Xiaodong LI Xufei and DU Peifang Auto Steel Division Research Institute Baoshan Iron & Steel Co. Ltd. Shanghai China State 《Baosteel Technical Research》2012,6(1):3-6
Cold-rolled martensitic steel sheets produced on continuous annealing lines with water quenching facility,have advantages of high strength and low alloying element contents.These are in good accordance with the trend of light-weighting and fuel saving for automotive steel.In this article,a cold-rolled martensitic steel is studied to investigate the effect of annealing parameters on its mechanical properties.It is found that the quenching temperature and the slow cooling speed as well as the overageing temperature have significant influence on the strength of the experimental steel.The temperature zone at which the austenite decomposition is slow or has not started may be chosen as the quenching temperature to ensure the steel’s strength stability.The slow cooling speed also influences the steel’s strength greatly.A high cooling rate will lead to significantly higher strength.Tempering would decrease the steel’s tensile strength but would increase its yield strength. 相似文献
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以C-Mn-Si系冷轧马氏体钢为研究对象,分析了退火工艺对超高强马氏体钢强度和冷弯性能的影响。由于碳含量高,试验用钢淬透性良好,当水淬入口温度在710℃及以上时,都能获得极高的抗拉强度和稳定的马氏体组织。随过时效温度升高,马氏体钢抗拉强度降低、延伸率升高;而屈服强度和冷弯性能则先升后降,在180℃过时效时具有最高的屈服强度和最优的冷弯性能。经扫描电镜和显微硬度分析发现,过时效温度的变化会直接影响马氏体钢中的碳化物析出及粗化,当过时效温度大于200℃时,试验用钢碳化物开始粗化,降低了马氏体钢的宏观冷弯性能。 相似文献
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Hsun Hu 《Metallurgical and Materials Transactions A》1982,13(7):1257-1262
Experimental studies of cold-rolled sheets from a series of silicon-phosphorus (0.07 pct P, variable Si) steels showed that,
depending on the silicon content, a dual-phase sheet can be produced with 70 ksi (483 MPa) yield strength, 100 ksi (690 MPa)
tensile strength, 15 pct elongation (in one inch), and anr
mvalue of about 1.8. The relatively low elongation value is believed to be due to quench aging. Further development to increase
hardenability and reduce the required cooling rates is expected to improve the ductility without reducingr
mvalues. 相似文献
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Woo Chang Jeong 《Metallurgical and Materials Transactions A》1998,29(2):463-467
To understand the bake hardening (BH) behavior in an actual automotive part, 40 tensile specimens were machined from the actual
press-formed outer-door panel of a compact car and both bake and work hardenability distribution data were determined. Strain
applied by actual press forming was estimated from the work hardening data. Finally, the effects of prestraining mode and
amount on ambient aging and BH response were also investigated. The BH widely ranged from 10 to 54 MPa and the work hardenability
was between 17 and 82 MPa, depending on panel location. Bake hardening in the outer-door panel decreased as the work hardening
increased, indicating that the BH steel must be applied to the shallow drawn parts in order to maximize the BH effect in dent
resistance. In order to establish the effects of prestrain and ambient aging time on the age and subsequent BH, the specimens
were prestrained and aged at ambient temperature for various time intervals, and then baked at 170 °C for 20 minutes. In the
as-temper-rolled and press-formed condition, the steels were extremely resistant to ambient aging. However, it was found that
a 0.3 pct tensile prestrain was sufficient to initiate ambient aging within 1 day, and the effect was accelerated with greater
prestrain. With 8 days of ambient aging, all prestrained steels exhibited 20 to 25 MPa of age hardening. Irrespective of prestrain
amount in the range of 0.5 to 5.0 pct, the BH decreased as the aging time increased. 相似文献
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《Baosteel Technical Research》2020,(2)
Two experimental steels with tensile strength above 980 MPa were prepared to investigate the effect of prestrain and baking on their mechanical and fracture behaviors. The experimental results reveal that,for both experimental steels,with increases in the prestrain level,the bake hardening value increases before reaching a maximum point,and then decreases with further increases in the prestrain level. The results of a "bending-baking-secondary bending"test indicate that the secondary bendability deteriorates at a high level of prestrain. The yield strength of the experimental steels was found to increase and the elongation to decrease after high levels of prestrain and bake hardening. Fracture morphology images indicate that a high prestrain level is associated with shallow dimples and more and larger local cleavage areas. 相似文献
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E. B. Yakovleva A. G. Vetrenko A. V. Antonov R. R. Kuramshin A. V. Gorbunov 《Steel in Translation》2012,42(12):830-832
In accordance with the EN 10268:2006 standard, a technology for the production of high-strength cold-rolled strip (thickness 1.8 mm) from microalloyed HC420LA steel has been developed and introduced at OAO Magnitogorskii Metallurgicheskii Kombinat (MMK). The technology is regarded as satisfactory and permits efficient order fulfillment. In 2011, ~850 t of such strip was delivered to customers, with an economic benefit for the plant of more than 1.1 million rubles. 相似文献
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利用多功能连续退火模拟器Multipas对屈服强度为380MPa的低硅型冷轧低合金高强钢板连续退火生产工艺进行了模拟,研究了在820,800,780℃三种不同退火温度和60,120,160m·min-1三种不同退火速度下,连退工艺对冷轧低合金高强钢板组织、力学性能的影响.结果表明,在不同的退火温度、退火速度下钢板退火组织的晶粒度基本相同,采用较低的退火温度和较高的退火速度时,可获得较好的强化效果.同时指出,在较高的连续退火温度下,退火速度对力学性能的影响较为显著. 相似文献
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V. L. Mazur 《Steel in Translation》2011,41(9):756-760
The aspects of cold rolling and subsequent coiling that affect the quality of the steel strip produced are identified on the
basis of theoretical and experimental research and production experience at various steel plants. The influence of the strip
width and thickness, the surface temperature, the temperature of the rolled metal, and other factors on the stress-strain
state of the coils is established. Rational rolling and coiling conditions at continuous and reversible mills are recommended. 相似文献
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In this study,the scale and internal oxidation of hot-rolled ultra-high strength steel sheets were characterized.It was found that both the formation of the scale and the internal oxidation of Si and Mn depended on the coiling temperature and position of the steel sample on the strip coil.At a relatively high coiling temperature,a large amount of internal oxidation was observed on the samples cut from the middle of the coil.The depth of the internal oxidation zone exceeded 10 μm and a thin iron layer covering the scale was observed in some cases.Pickling and cold-rolling experiments were conducted on selected samples.Scale pickling was found to be greatly delayed by the formation of an iron layer,which frequently resulted in under-pickled defects.In addition,pickling of the entire internal oxidation zone was difficult,except at the grain boundaries,where the degree of internal Si and Mn oxidation was enriched.The surface of the cold-rolled steel sheet was ruined by the remaining oxidation zone in the subsurface of the pickled steel.The internal oxidation of hot-rolled ultra-high strength steel must be precisely controlled to improve the subsequent surface quality of cold-rolled steel. 相似文献
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Structure and mechanical properties of a Nb/Ti microalloyed steel, thermomechanically rolled on a strip-production facility, are evaluated. Small (0.02%) titanium addition to niobium-containing steel is found to increase precipitation while reducing grain-refining potential of niobium. This effect increases with increasing finish-rolling temperature, and is also reflected in an increased charpy energy transition temperature. A reduced tendency for precipitation in a nitrogen-free austenite together with the short interpass times in the finishing train, is assumed to reduce the tendency for pancaking, which is prerequisite for an effective grain refining. 相似文献
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V. L. Kornilov I. N. Mamaev A. P. Budanov K. V. Smirnov M. A. Nikiforov 《Steel in Translation》2012,42(2):153-156
The influence of the basic technological factors on the loss of strip width in cold rolling is considered. The influence of technological factors and the state of the working rollers on the formation of light bands (impressions) at each working roller in the first cell of the old-rolling mill is investigated. Means of eliminating these problems in the production of cold-rolled steel are proposed. 相似文献
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