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摘要：热处理的本质是相变，而分析热处理相变的一般方法有XRD分析、热膨胀分析、金相分析、硬度分析、磁性分析等，但是每种方法均有各自的侧重点，且XRD与热膨胀分析都需要大型、昂贵的仪器设备，操作也复杂。高碳钢热处理过程中存在尺寸变化，于是本论文致力于提出一种新的、简单的方法，即二次称重法，通过分析高碳钢不同热处理密度变化、尺寸变化分析相变。对于质量分数1%的高碳钢而言，理论上奥氏体区淬火得到的马氏体转变为铁素体将引起试样3%的体积变化，1%的尺寸变化，而精度为1mg的电子天平能测量0.1%的微小变化。通过二次称重法分析了GCr15、9Cr18Mo、T9这三种高碳钢不同热处理密度变化，分析出高碳钢中马氏体转变为铁素体试样密度增大，体积收缩、尺寸减小。为了排除其他相（残余奥氏体、碳化物）的干扰，对GCr15与9Cr18Mo做了XRD定性分析，忽略碳化物的存在，找出一种只含马氏体的试样做热膨胀实验，分析出马氏体转变为铁素体引起的尺寸变化，并与二次称重法测量结果比较，从而验证了二次称重法分析高碳钢中马氏体转变为铁素体尺寸变化的准确性。5113
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关键词： 热处理；高碳钢；尺寸变化；密度变化；二次称重法;毕业论文
Phase Structure and Density Change of High-carbon Steel with Different Heat Treatment
Abstract：Heat treatment is the nature of the phase transition，and general methods to analyze phase transition in heat treatment are XRD analysis, thermal expansion analysis, metallographic analysis, hardness analysis, magnetic analysis, and so on. But each method has its own focus, and XRD analysis and thermal expansion analysis require large, expensive equipments, the operation is complicated. There is dimensional change in heat treating process of High carbon steel, so this paper dedicated a new, simple method that is a secondary weighing method which analyses different density and dimensional change of high-carbon steel with different heat treatment to analyze the phase transition. For the high-carbon steel with Mass fraction of 1%, theoretically, phase transition during martensite changing into ferrite will cause volume change of 3%, dimensional change of 1%, and now, electronic balance with the accuracy of 1mg can measure slight change of 0.1%. by the secondary weighing method, this paper analyzed density of GCr15, 9Cr18Mo, T9 three kinds of high carbon steel with different heat treatment, it concluded that transformation of martensite changing into ferrite in high carbon sample caused density increasing, volumetric shrinkage, size reducing. In order to rule out other phase (austenite, carbides) interference, this paper did XRD qualitative analysis on 9Cr18Mo and GCr15, and found a sample only containing martensite to do thermal expansion experiments. It analyzed dimensional changes during transformation of martensitic changing into ferrite, and the result was compared with that by the secondary weighing method, it verified accuracy of the secondary weighing method analyzing the dimensional changes during transformation of martensite changing into ferrite in high-carbon steel.
Key Words: Heat treatment；High-carbon steel；Dimensional change；Density change；Secondary weighing method
目录
1 绪论 1
1.1 钢铁材料 1
1.2 高碳钢发展概况 2
1.3 高碳钢的热处理技术 3
1.3.1 奥氏体化 3
1.3.2 退火和正火 4
1.3.3 淬火与回火 5
1.4 高碳钢热处理相变分析 7
1.4.1 高碳钢热处理相变分析手段 7