共查询到19条相似文献,搜索用时 140 毫秒
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《机电产品开发与创新》1998,(4)
锰低温钢奥氏体界面元素不平衡儒聚及其脆断机制的研究采用低温和超低温钢时,主要选择对象是镍钢和镍铬奥氏体不锈钢,但由于其资源短缺,价格昂贵,强度不高以及在超低温下会呈现磁性等问题而难以满足要求。从七十年代末起,国内外材料专家大力研究含锰的低温钢,但在研究这类钢时发现高锰奥氏体低温钢在超低温时往往出现脆性断裂,影响了这类钢的正常使用。国外对其脆断机制有过多种解释,但在理论上和实践中都不能得到较好的说明和证实。国内学者在八十年代中,通过试验发现这类钢低温脆断的冶金根源是锰在奥氏体晶界上的不平衡偏聚,使… 相似文献
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锰对高铬铸铁奥氏体冷却转变过程的影响 总被引:3,自引:0,他引:3
研究了锰对高铬铸铁奥氏体冷却转变过程的影响。研究结果表明,锰增加奥氏体化温度下碳和合金元素的平衡浓度,从而大大增加奥氏体的稳定性;在液火冷却转变中,锰增加合金的淬透性,提高大截面锰铸的淬火硬度,但增加小截面铸件的残余奥氏体量;在退火冷却转变中,锰使退火变得困难,退火硬度有所增加;以锰提高高铬铸铁的淬透性是十分有效的,但其加入量应与铸件截面尺寸相适应。 相似文献
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《机械工程学报》2015,(14)
对25Cr2Ni2Mo V低压转子钢焊接模拟件进行低周疲劳性能试验,测得焊接接头应变与疲劳寿命关系式,对比分析接头不同区域低周疲劳性能,确定热影响区是接头低周疲劳性能的薄弱环节。进行焊接接头硬度分布测定、疲劳裂纹扩展路径金相分析以及热影响区原奥氏体晶界元素偏聚行为俄歇分析等一系列试验。结果表明,焊接接头热影响区存在大硬度梯度的软硬界面,在疲劳载荷作用下形成应变集中,导致焊接构件低周疲劳性能弱化;在热影响区扩展过程中,疲劳裂纹遇到原奥氏体晶界往往会沿着晶界发生偏折,并在晶界上形成一定程度的割裂;俄歇分析表明热影响区原奥氏体晶界存在明显的杂质元素S和合金元素Cr的偏聚,其共同作用致使该区抗疲劳裂纹扩展性能弱化,从而降低整个焊接构件的低周疲劳性能。 相似文献
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介绍了55SiMnVB钢冲击试验方法、试验数据以及宏观、微观断口分析结果,并将这些数据、结果与显微组织结合起来进行了讨论,就本钢种的回火脆性与冷脆问题发表了一些看法。作者认为脆化除因磷及其他杂质元素在晶界附近偏聚外,“硼相”在晶界上形成可能是其主要原因。 相似文献
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磷对高锰钢热塑性的影响 总被引:4,自引:1,他引:4
奥氏体高锰钢的锻造工艺性能十分差,它一直是工程中难以解决的技术问题.利用Gleeble-3500热模拟试验机测试不同杂质含量高锰钢的热塑性,研究磷对高锰钢热塑性的影响规律.利用KYKY-2800型扫描电子显微镜分析高锰钢试样合金元素和杂质元素的成分分布.同时,研究了锻造高锰钢的常规力学性能,并与铸造高锰钢进行对比.结果分析表明,磷显著降低高锰钢的零塑性温度、缩小高锰钢的塑性温度区间,并且,高锰钢零塑性温度与磷含量之间的关系为:T=1 220-1 520·wp%.因此,磷是导致高锰钢锻造工艺性能差的主要原因.其原因是它在奥氏体晶界偏析形成Fe-(Fe Mn)3P类低熔点共晶组织.锻造高锰钢的力学性能明显优于铸造高锰钢,因此,锻造处理将使高锰钢的应用领域进一步扩大. 相似文献
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Elongated inclusions, particularly MnS, contribute significantly to reduced ductility and toughness in hot rolled steel but earlier research indicated that these properties can be improved by titanium additions. Such additions to a steel result in titanium being dissolved in manganese sulphide or MnS being replaced by TiS and/or titanium carbosulphides. In the present study, a steel was designed to decrease alloying element segregation and to evaluate the effect of titanium on centreline sulphide precipitates. Precipitates were identified by using scanning electron microscopy and characterized by the use of transmission electron microscopy following sample preparation by focused ion beam milling techniques. Iron–titanium‐sulphides form in close proximity to MnS precipitates that contain iron. Evidence is provided that an increase in the titanium content of steel leads to an increase in the percentage of titanium contained in the iron sulphides and a decrease in the iron content of MnS inclusions. 相似文献
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A novel approach to simulate segregation at the centreline of continuously cast steel using laser-scanning confocal microscopy 总被引:1,自引:0,他引:1
A concentric solidification technique was employed to simulate the segregation of alloying elements that occur during solidification at the centreline of continuously cast steel. Microstructural development of low carbon steel upon solidification has been observed in situ in a laser-scanning confocal microscope. Sulphide precipitates that formed in the last remaining liquid were identified, and evidence is provided that segregation occurring at the centreline of steel slabs can reasonably be simulated by the use of the concentric solidification technique. 相似文献
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S. A. Butler 《Scanning》1987,9(5):205-214
An automated energy-dispersive spectrometer/scanning electron microscope (EDS/SEM) system has been applied to the study of segregation in low-alloy steels in which the base concentrations of the alloying elements are ? 1.5 wt%. The distribution of elements within segregation bands is measured at several hundred points arranged on rectangular grids. By using suitable calibration standards, an accuracy for an individual analysis of about ± 0.05 wt% (one standard deviation) is obtained. By using statistical analysis of whole sets of data, the effects of large relative errors in individual values are minimized, and useful results are obtained even for concentrations much less than 1.0 wt%. It is shown that the maximum-segregation ratio is unreliable as a measure of the severity of segregation, and is of limited use as an indicator of the likely effects on steel properties. 相似文献
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为了提高耐磨高锰钢的淬透性、抗蠕变性和耐磨性,以各合金元素对锰钢性能影响为依据,通过大量的试验,提出了高性能耐磨锰钢原料的新配方,同时采用冒口加热新工艺和喷雾淬火新工艺等,大大提高了生产效率,满足了生产实际对锰钢耐磨性的要求. 相似文献
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通过设计合金元素锑、硼、磷加入量的三因素、二水平的正交试验,研究了合金元素及其加入量对蠕墨铸铁的蠕化率、基体组织、硬度和耐磨性的影响。优选出了合金元素的加入量为:0.03%Sb,0.03%B,0.25%P,并对新材料进行了模拟磨损试验。结果表明:新研制的低合金蠕墨铸铁比铬钼铜硼磷灰铸铁的综合相对耐磨性提高17.56%,而生产成本有所降低。 相似文献