多元高熵合金與304不□鋼異種銲接研究

Abstract

高熵合金為顛覆傳統合金觀念所創造的新合金，強調用五個以上的主元素來製作合金，每個元素含量不超過35 %，高亂度或高熵成為其異於傳統合金的基本特色，並具有許多學術及應用價值。此新合金可較傳統合金更耐蝕、更耐磨、更耐高溫、硬度高且不易氧化，其應用範圍甚廣：例如利用其高硬度之特性，可用作高爾夫球桿頭；利用其耐蝕性佳，可使用於化學工廠、船艦之高強度材料；利用其耐磨及耐溫性，可用於高溫之工具、模具及刀具等。 但無論高熵合金應用於何處，如何將其與同質材料之間，或與異質材料之間，達成高強度、高品質的接合加工，則為研究高熵合金於實際應用階段中之重要課題。本研究主要目標為探討銲接對高熵合金機械性質與顯微組織之影響，並研究其銲接性能，作為未來實務應用參考，期望擴展其應用範圍。 本研究中以230及718超合金銲條與高熵合金自製銲條對四種不同之高熵合金及304不□鋼進行異種銲接研究，並探討其機械性質與顯微組織，進行一系列異種銲接研究分析。實驗方法包括銲接實驗、拉伸試驗、拉伸破斷型態SEM觀察、微硬度試驗、金相顯微組織觀察(OM、SEM)及成份分析(EDS)。 實驗結果顯示，四種不同材質之高熵合金以相同成份之銲條與AISI 304不□鋼異種銲接後，其銲件之機械性質優於以230及718超合金銲條銲接之銲件。高熵合金與相同成份之銲條銲接性能佳，其中FeCoNi0.5CrAl0.5高熵合金(HB高熵合金)以相同成份之高熵合金銲條進行與AISI 304不□鋼異種銲接之銲件，其銲道強度優於304不□鋼商用板材之強度。

The development of High-Entropy alloys has aroused considerable interest recently. Many investigations have been conducted on the microstructures, mechanical properties, corrosion resistance, heat treatment, thin film development, and phase identifications. These newly developed alloys have good corrosion and wear resistance, high-temperature mechanical properties, and specially physical and chemical properties with nanostructure.

This experimental research project aimed at the investigation of weldability testing and microstructure analysis of Gas Tungsten Arc Welding (GTAW or TIG) weldments of these high-entropy alloys. In this study, a new welding material was developed to make a decent dissimilar metal welding joint of this alloy with other stainless steels. Superalloys 230 and 718 were also used as the filler metal. A series experiments included micro-hardness measurements, tensile testing, SEM and EDS analysis were conducted in this investigation.

The experimental results have lead to the following conclusions： 1.The weldment with high-entropy filler metal has the best mechanical strength and ductility. 2.The tensile strength of dissimilar metal joint weldment of high-entropy alloy and stainless steel 304 is greater than that of stainless steel 304. 3.High-entropy alloy can be used as welding filler metal for the joining of same type high-entropy alloy.