Mini-Thixoforming of High-Alloyed CPM REX 121 Steel
Mini-Thixoforming of High-Alloyed CPM REX 121 Steel
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DOI：
10.4028/www.scientific.net/amr.887-888.1156
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
D. Aišman;K. Rubešová;Š. Mikmeková
中科院分区：
文献类型：
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作者：
D. Aišman;K. Rubešová;Š. Mikmeková
触变成型是一种非常规的半固态成型工艺，通过该工艺可以使用单一成型操作制造复杂形状的产品。它甚至可以应用于难以成型的材料，包括那些无法通过传统方法加工的材料。如今，商业半固态加工用于低熔点材料，主要是铝和镁合金。由于其技术复杂性，高熔点合金的触变成型仍在开发中。因此，本实验计划主要针对粉末冶金生产的熔点高于 1200 °C 的工具钢 CPM REX 121。该钢合金元素总含量为37.5%。由于 Co、Mo、W、V 和 Cr 等合金元素含量较高，这种材料无法通过常规方法形成。本实验的目的是探索其半固态成型的潜力并找到合适的加工参数。实验成型在微型触变成型模具中进行，这是一种专门为这种触变成型变体开发的工具，旨在生产非常小的零件。通过光学和电子显微镜检查所得的微观结构。研究发现，半固态加工导致显微组织的发展，其中包括奥氏体晶粒、马氏体、铬和V-W-Mo复合碳化物以及碳化物部分熔化形成的共晶。
Thixo-forming is an unconventional semi-solid forming process, by which complex-shaped products can be manufactured using a single forming operation. It can even be applied to difficult-to-form materials, including those which are impossible to process by conventional methods. Today, commercial semi-solid processing is used for low-melting materials, primarily aluminium and magnesium alloys. Due to its technological complexity, thixo-forming of high-melting alloys is still under development. For this reason, the present experimental programme was focused on the tool steel CPM REX 121 with a melting point above 1200 °C produced by powder metallurgy. The total content of alloying elements in this steel is 37.5 %. Owing to the high levels of alloying elements, namely Co, Mo, W, V and Cr, this material cannot be formed by conventional methods. The purpose of the present experiment was to explore its potential for forming in semi-solid state and to find suitable processing parameters. Experimental forming took place in a mini-thixoforming die, a tool specially-developed for this thixo-forming variant intended for producing very small parts. The resulting microstructures were examined by means of optical and electron microscopy. It was found that semi-solid processing leads to the development of microstructure with austenitic grains, martensite, chromium and V-W-Mo complex carbides and also a eutectic formed by partial melting of carbides.