C-250麻時效鋼銲件之機械性質研究與熱處理之影響

Abstract

麻時效鋼是一種具高強度的材料，只需經過相當簡單的熱處理後，即可獲得相當高的強度與甚佳的韌性。此外，成型性佳，尺寸變化非常小，又有良好的銲接性，非常適用於航太工業的使用。 本文是在探討C-250麻時效鋼，以惰氣鎢極電弧銲（GTAM）來進行不加填料的對接銲接。主要是研究不同銲接參數和不同銲後熱處理對銲件之機械性質及微觀組織的影響。 實驗方法包括拉伸測試、微硬度量測、金相顯微組織觀察及SEM破斷面分析。 由實驗結果顯示：熱輸入量小、走速較快的銲接參數B較佳。而無論是母材或是銲件，最佳的熱處理條件是：均質化（1035℃/1hr）加固溶處理（820℃/1hr），再以510℃/3hr時效處理，可以使銲件恢復近乎母材的機械性質，比一般的麻時效鋼時效條件480℃/3hr要好。

Maraging steel is one of several useful high strength materials. It only needs very simple heat treatment and can obtain much higher strength and good ductility. It's formability is better, and dimension variation is very small. It also has excellent weldability. Therefore it is very suitable to be used in airplane industry. This research waw to explore the weldability of C-250 maraging steel under Gas tungsten Arc Welding (GTAW) process without filler metals. The purpose of this investigation was to study the influence of welding conditions and the post weld heat treatment to the mechanical properties and microstructures of C-250 maraging steel weldment. Series of experimentals included tensile test, microhardness test, optical metallographic examination, and SEM obervation. The experimental results showed that the welding condition B which had smaller heat input and faster welding speed is better. The best heat treatment, welded or not, is homogenization at 1035℃ for one hour, solution treatment at 820℃ for one hour, then aging at 510℃ for three hours. The mechanical properties of weldment can be almost recovered, and is even superior to normal aging condition of maraging steel weldment.