螺絲、螺帽等扣件在生活中隨處可見，一個在各大領域扮演非常重要的角色。業界上，淬火鋼都會做回火處理，以得到符合市面基本需求之機械性質，本研究發現到35ACR低合金鋼的數據在回火攝氏250度下出現明顯脆性現象。
本研究目的在於35ACR在不同回火溫度下之脆性分析。研究不同熱處理條件的機械性質。機械性質包括衝擊、拉伸與扭轉，加工得出試片後為素(原)材，經熱處理得到正常化、淬火以及攝氏150~700度間的回火材料。執行衝擊、拉伸與扭轉實驗、得出各項數據並觀察破斷面與金相組織。在回火後產生脆化現象處，針對晶界處拍SEM並打EDS分析元素分布，以說明是否脆性析出物產生，導致脆性現象。

Fasteners such as screws and nuts can be seen everywhere in life, and one plays a very important role in various fields. In the industry, quenched steel will be tempered to obtain the mechanical properties that meet the basic needs of the market. This study found that the data of 35ACR low alloy steel showed obvious brittleness phenomenon when tempered at 250 degrees Celsius.
The purpose of this study is to analyze the brittleness of 35ACR at different tempering temperatures. The mechanical properties of different heat treatment conditions were investigated. The mechanical properties include impact, tensile and torsion. After processing, the test piece is a plain (raw) material, which is normalized, quenched and tempered between 150 and 700 degrees Celsius after heat treatment. Perform impact, tensile and torsion experiments, obtain various data, and observe fracture surfaces and metallographic structures. At the point where brittleness occurs after tempering, SEM is taken at the grain boundary and EDS is used to analyze the element distribution to indicate whether brittle precipitates are generated, which leads to brittleness.

摘要 i
ABSTRACT ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
第一章 緒論 1
1.1前言 1
1.2合金鋼概述 1
1.3 35ACR簡述 2
第二章 原理及文獻回顧 3
2.1合金元素在鋼的影響 3
2.2 鋼之正常化、淬火與回火 9
2.2.1正常化 9
2.2.2淬火 9
2.2.3回火 10
2.3回火脆性 11
2.3.1低溫回火脆性 11
2.3.2高溫回火脆性 12
第三章 實驗步驟與設備 13
3.1實驗流程 13
3.2成分與加工 14
3.3熱處理參數與步驟 17
3.3.1正常化與淬火 17
3.3.2回火 17
3.4硬度量測 17
3.4.1硬度實驗 17
3.4.2硬度數據 18
3.5衝擊實驗 20
3.5.1衝擊實驗步驟 20
3.5.2衝擊數據 23
3.6拉伸實驗 23
3.6.1拉伸實驗步驟 23
3.6.2拉伸數據 23
3.7扭轉實驗 23
3.7.1扭轉實驗步驟 23
.7.2扭轉數據 24
3.8金相準備與觀察 24
3.9電拋與晶界分析 26
第四章 實驗結果與討論 28
4.1數據分析 28
4.1.1硬度數據 28
4.1.2衝擊數據 29
4.1.3拉伸數據 30
4.1.4扭轉數據 34
4.2破斷觀察 35
4.2.1衝擊破斷 35
4.2.2拉伸破斷 38
4.3金相觀察 42
4.4元素分析 55
第五章 結論 66
參考文獻 68

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