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Development of High Strength Non-Magnetic Steels for Concrete Applications

用于混凝土应用的高强度非磁性钢的开发

基本信息

批准号：
07555659
负责人：
TAKAKI Setsuo
金额：
$ 0.51万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

In this investigation, a process to refine austenite grains to below 1mum was established in an Fe-15% Mn alloy by the use of reversion of deformation induced bcc martensite. It was also confirmed that yield stress of this alloy can be increased to 0.8GPa by the ultra grain refining (before grain refining : about 0.2GPa), and that this alloy has sufficient ductility due to TRIP phenomenon. However, even a small amount of strain causes the formation of ferro magnetic bcc martensite in this alloy, so that this alloy is not suitable for the application to a field where complete non-magnetism is required. Thus, in a series of Fe-Mn binary alloys, the relationship between Mn content and microstructures, and grain size dependence of hcp (epsilon) martensitic transformation were discussed in connection with the mechanical properties of these alloys. The results obtained are as follows :(1) In alloys with 20% Mn or more, ferro magnetic bcc martensite was not formed until the fracture in tensile testing. In Fe-20-27% Mn alloys, epsilon martensite with non-magnetic nature is induced during deformation and this contributes to a great increase in tensile strength.(2) When these alloys have a large grain size (around 100mum), however, they undergo brittle fractures in a early stage of deformation along platelet epsilon martensite or austenite grain boundary. It is also cleared that grain refining to 10mum or below is indispensable for the suppression of such brittle fractures.(3) Grain refining of austenite and the use of deformation induced epsilon martensite enabled the production of non-magnetic high-strengthened steels with the tensile strength of above 1.1GPa and moderate ductility.

利用形变诱发体心立方马氏体的回复，建立了Fe-15%Mn合金奥氏体晶细化到1微米以下的工艺。经超细化处理后，该合金的屈服应力可提高到0.8 Gpa(细化前约0.2 Gpa)，并且由于TRIP现象，该合金具有足够的塑性。然而，即使是少量的应变也会导致该合金中形成铁磁性体心立方马氏体，因此该合金不适合于要求完全无磁性的领域。因此，在一系列Fe-Mn二元合金中，结合合金的力学性能，讨论了合金中Mn含量与显微组织的关系，以及HCP(Epsilon)马氏体相变的晶粒度关系。结果表明：(1)在含锰量为20%或更高的合金中，铁磁性体心立方马氏体在拉伸断裂后才形成。在Fe-20-27%Mn合金中，变形过程中诱发了非磁性的β马氏体，这有助于提高抗拉强度。(2)当合金具有较大的晶粒度(约100微米)时，它们在变形早期沿片状β马氏体或奥氏体晶界发生脆性断裂。(3)奥氏体的细化和形变诱发马氏体相的使用，使无磁高强钢的抗拉强度达到1.1 Gpa以上，塑性适中。