【正文】 process. According to the product technology and process requirement, can undertake rapid cooling, oil quenching cooling, disposable gas quenching cooling, etc. By gas quenching way before the quenching cooling nitrogen and helium gas, and now the use of air jet, the strong in fast speed, quenching cooling after only extremely thin surface oxidation, are pale, parts, and still beautiful color saved a great deal of nitrogen and inert gas, so that treatment costs will decline further. Vacuum lowpressure carburizing bined with highpressure gas quenching is an advanced carburizing today, it has carburizing speed, excellent carbide organization ,quenching cracking and little deformation, saving energy and carburizing agent raw materials, carburized parts surface quality is good, be helpful for environmental protection etc. (Ⅱ ) heat treatment equipment: The trend of foreign heat treatment furnace development: (1) stove based on the power is increasing, oil for heat treatment furnace ratio decreasing. (2) To product surface quality request more strictly controlled atmosphere heat treatment furnace, this occupies an important position still. (3) Lining tends to use of lightweight materials, the application in resistance furnace with heatresistant ponent and nonmetallic furnace the proportion of heating elements increase gradually. (4) The microputer and PLC accelerates the development of heat, and have with the other automation line of automatic heat treatment process of trend. eccentric shaft failure forms and preventing measures Shaft loading: fatigue, impact, tensile, pression, bending, twisting, cutting, wear, surface changes, size changes, etching, corrosion and other failure modes. (1) eccentric shaft under heavy load at work, subject to bending stress, wear and tear in the neck, by the main have occurred wear fracture and axial crack two circumstances parts (2) axial crack, axial crack is eccentric shaft parts mon failure form, this crack except material adverse outside, main is caused by excessive heat surface tension stress caused by its quenchhardening ability, due to merger part weeks than axial tensile stress surface , and material surface tensile stress of lateral performance under longitudinal, prevent such hardening layer, and promptl y tempering. (3) Axis failure form: There are insufficient due to fatigue resulting fatigue fracture, static strength due to lack of plastic deformation or brittle fracture, wear, and exceed the allowable range of deformation and vibration. (4) axial fracture is mainly reverse fatigue fracture. Chapter II Theoretical analysis Heat Treatment of eccentric shaft Unified Digital Code: A20202 【 Chemical Composition】 ⑷ (mass fraction) (%) C: ~ Si: ~ M n: ~ Cr: ~ 【 Mechanical properties 】 Sample blank size (mm): 15 Heat buried: The first quenching temperature: 880 ℃ 。 machinability high temperature in the state of normalizing or quenching and good, but after annealing poor。 關(guān)鍵詞：偏心軸、熱處理、滲碳、滲碳溫度、冷卻方式、滲碳層 第一章緒論 1. 1 前 言 偏心軸的作用是為了方便調(diào)節(jié)軸與軸之間的中 心距，偏心軸通常運(yùn)用在平面連桿機(jī)構(gòu)三角帶傳動中。截止 2020 年我國共出口空調(diào)壓縮機(jī)400 萬臺，比 2020 年出口空調(diào)壓縮機(jī)同期增長 27%。 (3)表面化學(xué)的研究，發(fā)展了各種表面防護(hù)熱處理及表面強(qiáng)化熱處理。 。 (Ⅱ )熱處理設(shè)備：國外熱處理爐的發(fā)展趨勢： （ 1） 以電能為熱源的爐子增多，熱源為煤氣的熱 處理爐比例逐漸減少。 第二章理論分析 偏心軸的熱處理 統(tǒng)一數(shù)字代號： A20202 【化學(xué)成分】⑷（質(zhì) 量分?jǐn)?shù)） （ %） C: ~ Si: ~ Mn: ~ Cr: ~ 【力學(xué)性能】 試樣毛坯尺寸 （ mm）： 15 熱處埋： 第一次淬火加熱溫度 ： 880℃ ；冷卻劑 ： 水、油 第二次淬火加熱溫度 ： 780? 820℃ ；冷卻劑：水、油 回火加熱溫度 ： 200℃ ；冷卻劑：水、空 抗拉強(qiáng)度 b? ≥ 835MPa 屈服點(diǎn) s? ：≥ 540 Mpa 斷后伸長率 ? :≥ 10% 斷面收縮率 ? :≥ 40% 沖擊吸收功≥ 47J 布氏硬度 ? ?3000/100HBS （退火或髙溫回火狀態(tài)）： ≤ 179 【主要特件】 與 15Cr鋼相比，有較高的強(qiáng)度及淬透性，在油中臨界淬透直徑達(dá) 4~22mm，在水中臨界淬透直徑達(dá) 11? 40mm，但韌件較差，此鋼滲碳時晶粒仍有長大傾向，降溫時直接淬火對沖擊韌性影響較大，所以滲碳后需二次淬火以提高零件心部韌性，無回火脆性；鋼的冷應(yīng)變塑性高，可在冷狀態(tài)下拉絲；可切削性在髙溫正火或調(diào)質(zhì) 狀態(tài)下良好，但退火后較差；焊接性較好，焊后一般不需熱處理，但厚度大于 15mm 的零件在焊前需預(yù)熱到 100? 150℃ 。滲碳時鋼的晶粒有長大傾向，所以要求二次淬火以提高心部韌性，不宜降溫淬火。 、照金相組織及測硬度梯度 相顯微式樣的制備包括取樣、磨制、拋光、浸蝕等工序。拋光的目的是去除細(xì)磨時遺留下來的細(xì)微磨痕從而獲得光亮的鏡面。浸蝕完畢后立即用清水沖洗，然后用酒精沖洗， 最后用吹風(fēng)機(jī)吹干，式樣即可置于金相顯微鏡上進(jìn)行觀察。 金相分析與討論 通過以上相關(guān)實(shí)驗(yàn)過程及結(jié)果，我們可以得到將 20Cr 偏心軸進(jìn)行滲碳處理后獲。浸蝕主要是依靠浸蝕劑對金屬的溶解或電化學(xué)腐蝕過程，使金屬式樣表面的晶粒與晶界及各組成相之間呈現(xiàn)輕微的凹凸不平，在顯微鏡下就可以清楚地觀察到式樣表面，浸蝕時間要適當(dāng)，一般式樣磨面發(fā)暗時就可停止。式樣在每一號砂布（紙）上磨制時，要沿一個方向磨，切忌來回磨削，而且要對式樣施加適當(dāng)?shù)牧Α? 擴(kuò)散降溫：滲層深≥ 時，可轉(zhuǎn)入擴(kuò)散降溫，調(diào)整煤油滴量 100? 140 滴 /分， 10? 30mm 水柱。此外，也可在調(diào)質(zhì)狀態(tài)下使用，用于制造工作速度較大并承受中等沖擊載荷的零件。 （ 3） 軸的失效形式：主要有因疲勞強(qiáng)度不足而產(chǎn)生的疲勞斷裂、因靜強(qiáng)度不足而產(chǎn)生的塑性變形或脆性斷裂、磨損、超過允許范圍的變形和振動等。以前采用氣淬方式冷卻的淬火氣體有氮?dú)?、氦氣等，現(xiàn)在用空氣強(qiáng)烈噴射，使工件在極快速度下冷卻，淬火后表面僅有極薄的氧化色膜，呈灰白色，零件色彩依然美觀，而節(jié)約大量氮?dú)夂投栊詺怏w，使熱處理成本進(jìn)一步下降。隨著真空技術(shù)的進(jìn)步，真空熱處理向著提高爐子工作溫度，自動化方向發(fā)展。對金屬中的組織轉(zhuǎn)變規(guī)律及組織與性能之間的關(guān)系不斷了解，進(jìn)而發(fā)展新的熱處理工藝。偏心軸帶動機(jī)器的轉(zhuǎn)動，是機(jī)械制造中不 可 少的零件。從理論上分析滲碳溫度、時間和冷卻方式直接淬火、一次淬火、二次淬火等因素對力學(xué)性能、組織的影響。 Coolant: water, air Tensile strength ≥ 835MPa Yield point: ≥ 540MPa LaSalle epigastria long rate: ≥ 10% Section shrinkage: ≥ 40% Shock absorption≥ 47J impact energy Brinell hardness (annealed or high temperature tempering state): ≤ 179 【 Main Special items】 Compared with the 15Cr steel , it has higher strength and its quenchhardening ability in oil critical quenching, up to 4 ~ 22mm diameter appearing in water to critical quenching of 11 ~ diameter 40mm lottery, but the firmware is poor, when the steel carburizing Grains are still growing tendency, when the direct quenching temperature on impact toughness of greater impact, so the secondary quenching after carburizing need to improve the toughness of the Ministry of parts heart, no temper brittleness。 Coolant: water, oil Tempering heating temperature: 200 ℃ 。 water column 30 ~ 60mm. Diffusion Cooling: ≥ deep diffusion layer, it can spread into the cool, adjust the volume of kerosene drops of 100 to 140 drops / min, 10 to 30mm water column. released air. . Metallographic specimen preparation, according to the microstructure and hardness gradient measurements The preparation phase include microscopic pattern sampling, grinding, polishi