权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Influence of aluminum as alloying element on the microstructure of stainless steels with predominantly austenitic matrices

铝作为合金元素对奥氏体基体不锈钢显微组织的影响

基本信息

批准号：
274385700
负责人：
Professor Dr. Javad Mola, Ph.D.
金额：
--
依托单位：
Institut für Werkstofftechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/274385700?language=en
关键词：
Influence aluminum alloying element microstructure

项目摘要

In the first phase of the project, Al in quantities up to 7 mass-% was added to stainless steels to obtain steels with austenitic (six alloys), duplex (one alloy), and ferritic (one alloy) matrix microstructures. For steels containing austenite, the temperature dependence of tensile properties was determined. Al addition was associated with a clear increase in the stability of austenite evidenced by a decrease in the Mdγ→αʹ temperature. This effect correlates well with the SFE-raising effect of Al. Analysis of the temperature dependence of tensile properties and strain hardening behavior for austenitic and duplex alloys enabled to establish interrelationships among glide planarity, linearity of the strain hardening rate, and tensile elongation. The ferritic steel containing 7 mass-%Al showed embrittlement caused by the formation of B2-(Ni,Fe)Al intermetallics. B2 intermetallics could also be induced in the duplex alloy by an aging treatment. One of the objectives of the second phase of the project is to design Al-alloyed steels exhibiting maximum tensile elongation near room temperature. Insights from the first phase of the project will serve as guidelines for the design of the chemical composition. The design is based on the recognition that C, Cr, Ni, Mn, and Al decrease the Mdγ→αʹ temperature. Reportedly, all of these elements except Al have a similar effect on martensite start (Ms) temperature. Given the consistency of the effect of alloying elements on Mdγ→αʹ and Ms temperatures, Al addition to stainless steels is expected to decrease the Ms temperature. Therefore, one of the objectives of the second phase of the project is to re-examine the reported influence of Al on Ms temperature. Another objective of the second phase is to study the formation of B2 intermetallics in Al-alloyed ferritic stainless steels containing Ni. The straightforward dilatometry-based method introduced in the first phase will be used to study B2 precipitation in a series of alloys containing both Ni and Al. This knowledge is an aid in the design of duplex stainless steels with B2-strengthened ferritic constituent. Quenching and Partitioning (Q&P) processing is an effective method of obtaining 3rd generation advanced high-strength steel properties in steels with martensitic-austenitic microstructures. Successful application of Q&P requires that the precipitation of cementite in martensite, a process that competes with the C enrichment of austenite, is inhibited. Al is regarded as an alloying element opposing the precipitation of cementite during austempering of TRIP-assisted steels. The last objective of the proposal is to study the influence of Al on the precipitation of paraequilibrium cementite in the martensitic constituent of martensitic-austenitic stainless steels and on the C enrichment of austenite.

在该项目的第一阶段，向不锈钢中添加高达7质量%的铝，以获得具有奥氏体（六种合金）、双相（一种合金）和铁素体（一种合金）基体微观结构的钢。对于含有奥氏体的钢，拉伸性能的温度依赖性被确定。Al的加入明显提高了奥氏体的稳定性，降低了Mdγ→α δ温度。这种效果与铝的超临界流体萃取提高效果。奥氏体和双相合金的拉伸性能和应变硬化行为的温度依赖性的分析，能够建立滑移平面性，线性的应变硬化率，和拉伸伸长率之间的相互关系。含7质量%Al的铁素体钢表现出由B2-（Ni，Fe）Al金属间化合物的形成引起的脆化。通过时效处理，也可以在双相合金中诱导B2金属间化合物。该项目第二阶段的目标之一是设计在室温附近表现出最大拉伸伸长率的铝合金钢。该项目第一阶段的见解将作为化学成分设计的指导方针。该设计基于C、Cr、Ni、Mn和Al降低Mdγ→α δ温度的认识。据报道，除了Al之外，所有这些元素对马氏体起始（Ms）温度具有类似的影响。考虑到合金元素对Mdγ→α δ温度和Ms温度的影响的一致性，预期在不锈钢中添加Al会降低Ms温度。因此，该项目的第二阶段的目标之一是重新检查报告的Al对Ms温度的影响。第二阶段的另一个目的是研究含Ni的Al合金化铁素体不锈钢中B2金属间化合物的形成。在第一阶段中介绍的直接的基于电化学的方法将被用来研究B2沉淀在一系列的合金含有Ni和Al。这方面的知识是一个援助的设计双相不锈钢与B2强化铁素体成分。淬火和分配（Q&P）工艺是在具有马氏体-奥氏体显微组织的钢中获得第三代先进高强度钢性能的有效方法。Q&P的成功应用需要抑制马氏体中的马氏体沉淀，这是一个与奥氏体中的C富集竞争的过程。铝被认为是一种合金元素，在TRIP辅助钢的等温淬火过程中对抗铁素体的析出。该提案的最后一个目标是研究Al对马氏体-奥氏体不锈钢马氏体成分中准平衡铁素体析出和奥氏体中C富集的影响。