不銹鋼表面以電漿硬面銲覆鎢後之顯微結構特徵研究

Microstructural characterization of tungsten hardfacing of stainless steel by plasma transferred arc welding

林亮東(Liang-Tung Lin)

指導教授 ： 黃和悅

國立虎尾科技大學/工程學院/材料科學與工程系材料科學與綠色能源工程碩士在職專班/碩士(2016年)

摘要

本研究主要探討金屬鎢與肥粒鐵系不銹鋼進行電漿轉移電弧銲接合後的顯微組織及機械性質的影響。本實驗固定相同電流、氣體流量、落粉速率及銲槍間距，以改變不同銲接速度作為主要參數，實驗結果顯示，銲覆後生成的硬面層能相當有效的提升基材表面的硬度，而硬度致熱影響區時開始下降。顯微組織觀察發現，肥粒鐵系不銹鋼經銲接過後，由於冷卻速度過快，顯微組織會從原本的肥粒鐵組織轉變成麻田散鐵組織。當銲接速度較慢時，在晶界處會析出Fe-Cr-W的羽毛狀組織；銲接速度較快時，鎢容易與鐵生成Fe7W6相。並經電化學試驗，可以發現銲覆後生成的硬面層，有助於材料抵抗海水腐蝕的能力。

關鍵字

SUS430不銹鋼 ； 金屬鎢 ； 電漿轉移電弧銲 ； 硬面層

並列摘要

The aim of this study was to evaluate the influence of ferritic stainless steel on mechanical and microstructural properties of tungsten powder plasma transferred arc hardfacing. The independently controllable process parameters were identified based on their significant effect on weld bead geometry were welding speed, welding current, plasma gas flow rate, powder feed rate and nozzle to workpiece distance. The working ranges of all selected parameters were fixed except welding speed. The results indicated that the hardness values were more on the hardfaced surface and decreased towards the heat-affected zone and remained constant on the base metal. The microstructure observation showed that ferritic stainless steels experienced a martensitic transformation during rapid cooling of weld. In the case of lower welding speed, feather-like precipitations of a Fe-Cr-W rich phase were observed at the grain boundaries. However, a high welding speed favored the formation of the Fe7W6 intermetallic phase. The electrochemical results showed that the corrosion resistance of hardfacing alloy was improved by tungsten alloyed.

並列關鍵字

SUS430 ； Plasma Transferred Arc ； Tungsten ； hardfacing

參考文獻

[37] 陳昱豪，應用氣體鎢極電弧硬銲碳化鎢與不銹鋼之研究，國立虎尾科技大學，碩士論文，雲林縣，2015。

[14] 謝之駿、吳威德，沃斯田鐵系與肥粒鐵系異種不銹鋼多道銲接之相變化研究，銲接與切割，21卷4期，2011，頁32-45。

[21] A. Rokanopoulou, P. Skarvelis, G.D. Papadimitriou, Microstructure and wear properties of the surface of 2205 duplex stainless steel reinforced with Al2O3 particles by the plasma transferred arc technique, Surface & Coatings Technology, Vol.254, 2014, pp.376-381.

[23] K. Devendranath Ramkumar, Aditya Chandrasekhar, Aditya Kumar Singh, Sharang Ahuja, Anurag Agarwal, N. Arivazhagan, Arul Maxiumus Rabel, Comparative studies on the weldability, microstructure and tensile properties of autogeneous TIG welded AISI 430 ferritic stainless steel with and without flux, Journal of Manufacturing Processes, Vol.20, 2015, pp.54-69.

[24] S. Vafaeian, A. Fattah-alhosseini, Y. Mazaheri , M. K. Keshavarz, On the study of tensile and strain hardening behavior of a thermomechanically treated ferritic stainless steel, Materials Science & Engineering A, Vol.669, 2016, pp480-489.