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Degradation of alloy properties by super purification and optimum design of advanced steels by the best use of impurity elements

通过超净化降低合金性能，并通过杂质元素的最佳利用来优化设计先进钢

基本信息

批准号：
11305050
负责人：
MORINAGA Masahiko
金额：
$ 7.71万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11305050/
关键词：
impurity sulfur heat-resisting steel steam oxidation 鉄鋼材料微量元素合金設計不純物元素

项目摘要

Some of alloy properties degrade by super purification. The best use of impurity elements such as S and B is needed for the optimum design of advanced heat-resisting steels. The objective of this research is to investigate the effect of impurity elements on the steam oxidation resistance. The results on the S impurity are summarized as follows ;( 1 ) It was observed that a mass loss occurred in the advanced high Cr ferntic steels m the early stage of steam oxidation at 650℃. However, this mass loss decreased significantly in the S-containing steels.( 2 ) As S was an impurity element to segregate on the surface of the stee at 650℃ it worked to assist the Cr enrichment on the surface owing to the strong affinity of these two elements As a result, Cr_2O_3 could form easily on the steel surface in the early stage of steam oSon a far as tne steel contained S.( 3 ) S existed under the Cr_2O_3 oxide layer or at the interface between the oxide and the base steel. The existence of S at the inte … More rface suppressed severe Cr depletion under the oxide, resulting in good oxidation resistance even for a long time exposure to steam.( 4 ) It was stressed here that even Cr_2O_3 oxide specimen itself showed a mass loss after steam oxidation at 650℃. However, the S doping into Cr_2O_3 decreased such a mass loss.( 5 ) As might be expected from these results, this S effect was not remarkable in the low Cr steels (e.g., 2.25%Cr steel).The mass loss obseryed ferritic steels and Cr_2O_3 oxide during steam oxidation was interpreted as due to the formation of a volatile hydroxide, CrO_2(OH)_2, as reported previously in austltic steels. The presence of S at an impurity level probably suppressed the formation of he volatile compound. This is probably the reason why S is effective in increasing the oxidation resistance to steam but not to air. The S effect became dominant if the steels contained 50ppm S. This is an allowable amount of S since it does not degrade mechanical properties of the steels. Therefore, for the optimum design, 50〜100ppmS should remain in advanced high Cr ferritic steels. Less

超净化会降低合金的某些性能。在先进耐热钢的优化设计中，必须充分利用S、B等杂质元素。本研究的目的是探讨杂质元素对蒸汽抗氧化性的影响。研究结果表明：（1）先进高铬铁素体钢在650℃水蒸气氧化初期，有质量损失;然而，这种质量损失显着降低含S钢。（2）由于S是在650℃时偏聚在钢表面的杂质元素，由于S和Cr的亲和力强，有助于Cr在钢表面的富集，因此，含S的钢在蒸汽腐蚀初期容易在钢表面形成Cr_2O_3。（3）S存在于Cr_2O_3氧化层之下或氧化层与钢基体的界面处。S的存在性 ...更多信息表面抑制了氧化物下严重的Cr耗尽，即使长时间暴露于水蒸汽中也具有良好的抗氧化性。（4）在650℃蒸汽氧化后，Cr_2O_3氧化物试样本身也有质量损失。而在Cr_2O_3中掺入S则降低了这种质量损失。（5）从这些结果可以预期，这种S效应在低Cr钢（例如，在蒸汽氧化过程中，铁素体钢和Cr_2O_3氧化物的质量损失被解释为由于在奥氏体钢中形成了挥发性氢氧化物CrO_2（OH）_2。杂质水平的S的存在可能抑制了挥发性化合物的形成。这可能是S有效提高对水蒸气而不是空气的抗氧化性的原因。当钢中S含量为50 ppm时，S效应占主导地位。这是允许的S量，因为它不会降低钢的机械性能。因此，对于优化设计，在先进的高Cr铁素体钢中，应保持50 - 100 ppmS。少