發(fā)布時(shí)間：2018-11-22 12:43

【摘要】：針對(duì)低碳鋼的烘烤硬化和Cottrell氣團(tuán)的形成機(jī)制進(jìn)行了研究,探索了應(yīng)變時(shí)效初期Cottrell氣團(tuán)的形成、較長(zhǎng)時(shí)間時(shí)效后的碳化物沉淀以及熱處理態(tài)的烘烤硬化性能,分別測(cè)量了其BH值、應(yīng)力-應(yīng)變曲線和內(nèi)耗-溫度譜,并從原子層面揭示其烘烤硬化機(jī)理。主要研究結(jié)果如下:(1)當(dāng)預(yù)應(yīng)變量為2%、烘烤溫度為170℃時(shí),隨著烘烤時(shí)間的增加BH值與SKK峰的峰高有線性關(guān)系,他們的關(guān)系可以表示為BH=17119*hSKK-33;低碳鋼在200min烘烤時(shí)間內(nèi)的時(shí)效硬化機(jī)制主要是Cottrell氣團(tuán)強(qiáng)化,位錯(cuò)釘扎點(diǎn)即氣團(tuán)數(shù)量的增加是屈服強(qiáng)度增加的主要原因,碳原子在位錯(cuò)的濃度隨時(shí)效時(shí)間變化不大。(2)多種應(yīng)變時(shí)效工藝下,預(yù)變形由2%增加到5%,BH值降低,SKK峰峰高增加;在170℃時(shí)效,預(yù)變形由5%增加到16%,BH值降低,屈服點(diǎn)延伸率增加。(3)隨著熱處理保溫時(shí)間延長(zhǎng),平均晶粒尺寸不斷增大,晶粒的不均勻性逐漸增加,烘烤硬化值逐漸減小。與原始樣品相比,熱處理樣品的BH值較高。隨著熱處理保溫時(shí)間延長(zhǎng),間隙碳原子含量下降,SKK峰逐漸升高,間隙碳原子和Cottrell氣團(tuán)共同影響了BH值的變化。烘烤前后相比較,Snoek峰高降低,SKK峰高升高。(4)與原始樣品相比,熱處理樣品的BH值較高;隨著時(shí)效時(shí)間延長(zhǎng),間隙碳原子含量下降,SKK峰逐漸升高;熱處理后的樣品,在時(shí)效過(guò)程中,碳原子向晶界和位錯(cuò)擴(kuò)散的同時(shí)大量脫溶形成細(xì)小碳化物;在100 min時(shí)效時(shí)間內(nèi)出現(xiàn)的p2峰、麻點(diǎn)和強(qiáng)度的下降與過(guò)飽和碳原子的脫溶過(guò)程有關(guān);過(guò)飽和碳原子的脫溶造成軟化,使BH值下降致負(fù)值。
[Abstract]:The mechanism of baking hardening and Cottrell air mass formation of low carbon steel was studied. The formation of Cottrell air mass at the initial stage of strain aging, the carbide precipitation after long aging and the baking hardening property of heat treatment state were investigated. The BH values were measured respectively. The stress-strain curve and internal friction temperature spectrum are also studied, and the mechanism of bake hardening is revealed at atomic level. The main results are as follows: (1) when the prestrain is 2 and the baking temperature is 170 鈩，

本文編號(hào)：2349407