共查询到20条相似文献,搜索用时 15 毫秒
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通过光学显微镜、拉伸试验及背散射电子衍射,研究了退火温度对21Cr-0.3Cu超纯铁素体不锈钢显微组织、力学性能、成形性能和微观织构的影响。结果表明,试验钢经970 ℃退火时,晶粒细小且均匀,组织处于完全再结晶状态。退火温度低于970 ℃时,再结晶不完全;退火温度高于970 ℃时,再结晶晶粒异常长大,这两种情况均出现混晶组织。试验钢在970 ℃退火时,综合力学性能最佳,抗拉强度为473 MPa,屈服强度为315 MPa,伸长率35.7%。随退火温度的升高,试验钢的平均塑性应变比rm值先增加后减少。当退火温度达到970 ℃时,rm可以达到最大值1.82。γ纤维织构密度变化趋势与rm值一致,退火温度为970 ℃时,γ纤维增强明显,此时其取向密度达到最大值f(g)=20.56,成形性能最佳。 相似文献
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Influence of nonmetallic inclusion characteristics on the mechanical properties of rail steel 总被引:1,自引:0,他引:1
S. K. Dhua Amitava Ray S. K. Sen M. S. Prasad K. B. Mishra S. Jha 《Journal of Materials Engineering and Performance》2000,9(6):700-709
An extensive investigation has been carried out on six commercial heats of pearlitic rail steel to study the influence of
nonmetallic inclusion characteristics on the tensile, fatigue, and fracture toughness properties. The steels investigated
were made through the basic oxygen furnace (BOF)-continuous casting route and rolled in the rail and structural mill into
90 kg/mm2 ultimate tensile strength (UTS) grade rails. While tensile properties (yield strength [YS], UTS, and elongation) of the rail
steels investigated were found to be insensitive to inclusion type and volume fraction at their present level (0.23 to 0.45%),
the fracture toughness and high-cycle fatigue properties were found to be inclusion sensitive. The fracture toughness values
of the steels were found to range between 42.33 and 49.88 MPa √m; higher values, in general, were obtained in heats exhibiting
lower volume fractions (0.15 to 0.19%) of sulfide inclusions. The high-cycle fatigue limit, i.e., stress corresponding to 107 cycles, was found to be higher in cleaner steels, particularly in those with lower volume fractions of oxide inclusions.
This phenomenon was corroborated by scanning electron microscopy (SEM) observations of fracture surfaces, where oxide inclusions
in particular were found to be instrumental in crack initiation. Although fatigue life did not show any direct correlation
with the volume fraction of sulfides, elongated MnS inclusions were sometimes observed at crack initiation sites of fatigue-tested
specimens. 相似文献
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R. Cada 《Journal of Materials Processing Technology》1996,60(1-4):283-290
The paper concerns evaluation and comparison of formability of steel strips, which are used in Czech Republic for production of intricate deep stampings. The properties of sheet-metal which have the principal influence upon the success of deep drawing or strech-forming are described. Two methods used for determination of strain-hardening exponent are compared. It is concluded, that the method according to
SN 42 0436 is suitable for approximation of stress-strain curve of given sheet-metal only from point of view of functional values. The values of strain-hardening exponent, calculated by the method using maximum uniform elongation, are more strongly correlated with pure stretchability than are the values of it, calculated by the method according to
SN 42 0436. 相似文献
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为研究应变速率对汽车钢板冲压成形性能的影响,采用单向拉伸实验,对3种不同强度级别的典型汽车用钢板进行应变速率敏感性研究。结果显示,电镀锌BSUFD+Z钢板的屈强比对应变速率的敏感性最大,其次是烘烤硬化BH220钢板,敏感性最小的是双相DP600钢板;双相DP600钢板的硬化指数具有较大的应变速率敏感性,而电镀锌BSUFD+Z钢板和烘烤硬化BH220钢板的硬化指数对应变速率的敏感性较低;3种钢板的应变速率敏感指数,电镀锌BSUFD+Z钢板最大,烘烤硬化BH220钢板次之,双相DP600钢板最小。研究结果为汽车钢板快速冲压生产工艺设计提供了参考。 相似文献
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Effect of coating characteristics on friction and formability of Zn-Fe alloy electroplated sheet steel 总被引:7,自引:0,他引:7
Y. Liu 《Journal of Materials Engineering and Performance》1996,5(4):469-477
The effects of coating composition and coating weight on friction characteristics and formability under different deformation
modes, as well as their mechanisms, were studied on zinc-iron electroplated drawing-quality special-killed (DQSK) sheet steels.
Friction tests, simulative formability tests, and coating characterization were performed. The experiments revealed that the
iron concentration of the coating has a tremendous effect on friction in the deep-drawing operation, but only a slight effect
in the stretching operation. Uniaxial tension tests indicated that both coating weight and coating composition affectn-value andr-value. The dependence of friction characteristics,n-value, andr-value on iron concentration is related to the variation of coating hardness caused by the variation of iron concentration
in the coating. 相似文献
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对1.5 mm厚的301L不锈钢板材进行多道次冷轧试验,得到压下率分别为20%,30%,40%的板材;通过对冷轧板材的拉伸试验、金相分析、SEM分析、XRD衍射分析及硬度测试,研究冷轧压下率对301L不锈钢组织及性能的影响规律。研究表明,随着冷轧压下率的增大,301L不锈钢中的应变诱发马氏体会逐渐增多,材料的屈服强度由789 MPa提高至1260 MPa,抗拉强度由977 MPa提高至1317 MPa,显微硬度则提高了120 HV;材料出现晶粒碎化现象,产生细晶强化;同时,由于301L不锈钢中的马氏体相变,20%压下率的301L不锈钢拉伸应变硬化指数要高于30%压下率的301L不锈钢。 相似文献
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Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism
To further understand the hardening mechanism of austenitic manganese steel under actual working conditions,the work hardening ability was studied and the microstructures of austenitic manganese steel ... 相似文献
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The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10?4, 10?3, 10?2, 10?1 s?1 at 200 °C. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation. 相似文献
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将Mn-B系高强度贝氏体钢板轧成25 mm规格采用超快冷系统进行加速冷却。冷却后钢板可以获得710~850 MPa的高抗拉强度,但断后伸长率仅12.0%~13.0%。通过光学显微镜、扫描电镜、透射电镜等对钢板及单向拉伸断口的显微组织、析出物等进行分析。结果表明,在超快冷条件下钢板表层可以获得广泛的板条贝氏体组织,板条贝氏体中的渗碳体分布于板条及板条束间的界面上,形成类似珠光体的片层结构,明显提高钢板强度。在变形过程中,渗碳体内易生成微裂纹,降低基体组织的加工硬化能力,导致断后伸长率偏低、钢板塑性下降。 相似文献
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The industrial sequence for obtaining duplex stainless steels by rolling includes two annealing steps: one intermediate after the hot rolling, and the final one after the cold rolling. The aim of this paper is to study the consequences of deviations from the current industrial intermediate annealing temperature. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), together with X-ray diffraction (XRD), were used to investigate the microstructural changes of the steel. The only transformation observed was the precipitation of sigma phase for all the considered annealing conditions. A decrease in the heat treating temperature augmented the percentage of sigma phase, which generated an increase in tensile strength and hardness, concurrently with drastic reductions on ductility and impact resistance. In addition, compression testing and cold rolling at laboratory scale were done in order to compare the formability of the steel subjected to the new annealing conditions with the current industrial rolled products. On the other hand, the pitting potential of the thermo-mechanically treated samples was determined by potenciodynamic polarization tests. The electrochemical results showed that sigma phase markedly decreases the pitting potential. SEM observations revealed that pits appear mainly in regions adjacent to sigma phase, where secondary austenite forms. 相似文献
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R. C. Dorward 《Journal of Materials Engineering and Performance》1994,3(1):115-121
The forming behavior of Al-Cu-Mg-Mn alloy 2024 sheet with fine, equiaxed and coarse, elongated grain structures was characterized
in the O temper (fully annealed) and W temper (solution heat treated and quenched) conditions. The fine-grained materials
had better biaxial stretching capabilities in both tempers. The fine-grained O temper also had superior drawing and plane-strain
stretching properties. For the O temper, conventional tensile forming indicators such as elongation and strain ratio correlated
with ball punch depth, forming limit strains, and limiting draw ratio. Such correlations were not apparent in the W temper,
however, nor could the two tempers be compared on the basis of tensile data alone. 相似文献