Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel
Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel
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DOI：
10.1007/s11661-014-2701-7
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发表时间：
2015-03-01
影响因子：
2.8
通讯作者：
Theisen, W.
中科院分区：
文献类型：
--
作者：
Lefor, Kathrin;Walter, M.;Theisen, W.
Cr和Mn合金化的无镍奥氏体钢是传统含镍钢的替代品。这些钢种的氮合金化是有益的，有几个原因，如提高强度和耐腐蚀性。在液体中的低溶解度和δ铁氧体限制了通过常规冶金可以获得的最大n含量。通过气固相互作用，粉末冶金（PM）生产可以获得高含量的合金。适当的烧结参数决定了烧结件的性能。采用热等静压、超固液相烧结和固态烧结三种主要的粉末冶金工艺路线，研究了粉末冶金工艺路线和n含量对粉末冶金致密化、断裂和力学性能的影响。烧结路线是在热力学计算、差热分析和残余气体分析的帮助下设计的。采用x射线光电子能谱、二次电子显微镜和能量色散x射线能谱对断口表面进行了研究。通过拉伸试验和x射线衍射研究其力学性能和奥氏体稳定性。该研究表明，SLPS工艺在实现高含锰粉末材料高密度化的同时，通过气固相互作用成功地合金化了所需的n含量。所生产的样品的抗拉强度为1000兆帕，应变断裂率为60%，因此优于其他测试的生产路线以及传统的不锈钢奥氏体或马氏体等级。(C)作者2014。本文在Springerlink.com上以开放获取方式发布
Ni-free austenitic steels alloyed with Cr and Mn are an alternative to conventional Ni-containing steels. Nitrogen alloying of these steel grades is beneficial for several reasons such as increased strength and corrosion resistance. Low solubility in liquid and delta-ferrite restricts the maximal N-content that can be achieved via conventional metallurgy. Higher contents can be alloyed by powder-metallurgical (PM) production via gas-solid interaction. The performance of sintered parts is determined by appropriate sintering parameters. Three major PM-processing routes, hot isostatic pressing, supersolidus liquid phase sintering (SLPS), and solid-state sintering, were performed to study the influence of PM-processing route and N-content on densification, fracture, and mechanical properties. Sintering routes are designed with the assistance of thermodynamic calculations, differential thermal analysis, and residual gas analysis. Fracture surfaces were studied by X-ray photoelectron spectroscopy, secondary electron microscopy, and energy dispersive X-ray spectroscopy. Tensile tests and X-ray diffraction were performed to study mechanical properties and austenite stability. This study demonstrates that SLPS process reaches high densification of the high-Mn-containing powder material while the desired N-contents were successfully alloyed via gas-solid interaction. Produced specimens show tensile strengths >1000 MPa combined with strain to fracture of 60 pct and thus overcome the other tested production routes as well as conventional stainless austenitic or martensitic grades. (C) The Author(s) 2014. This article is published with open access at Springerlink.com