本文選題：珠光體 + 奧氏體晶粒尺寸��； 參考：《材料導(dǎo)報》2017年02期

【摘要】：探索了奧氏體晶粒尺寸對珠光體等溫轉(zhuǎn)變組織特征以及對韌性性能的影響規(guī)律。研究表明,在相同等溫轉(zhuǎn)變溫度下,珠光體片層間距無明顯變化,隨奧氏體晶粒尺寸的增加,先共析鐵素體量減少而珠光體團尺寸增加。珠光體斷裂韌性受控于裂紋前沿塑性影響區(qū)尺寸(1~2)δc,其中δc為臨界裂紋張開位移,當(dāng)原奧氏體晶粒大于(1~2)δc時,裂紋擴展阻力主要來自穿越珠光體片層α、θ相的頸縮、破斷。當(dāng)原奧氏體晶粒尺寸接近或小于(1~2)δc時,裂紋主要沿晶界、珠光體團界、α+θ片層界面擴展,通過擴展路徑發(fā)生多次彎折消耗能量,隨原奧氏體晶粒尺寸增加,準(zhǔn)靜態(tài)斷裂韌度J變化幅度較小。而沖擊韌性缺口前沿塑性影響區(qū)遠大于原奧氏體晶粒,大角度晶界將促使裂紋的轉(zhuǎn)折而提高擴展阻力,提高裂紋前沿塑性區(qū)大角度晶界密度有利于提高沖擊功,沖擊韌性Ak隨晶粒尺寸的增加顯著下降。
[Abstract]:The effect of austenite grain size on the microstructure and toughness of pearlite isothermal transformation was investigated. The results show that the lamellar spacing of pearlite does not change obviously at the same isothermal transition temperature. With the increase of austenite grain size, the amount of preeutectoid ferrite decreases and the size of pearlite cluster increases. The fracture toughness of pearlite is controlled by the size of (1 / 2) 未 c, where 未 c is the critical crack opening displacement. When the original austenite grain is larger than (1 / 2) 未 / c, the crack propagation resistance is mainly due to the necking and breaking through 偽, 胃 phases of the pearlite lamellae. When the grain size of the original austenite is close to or less than (1 / 2) 未 c, the crack mainly propagates along the grain boundary, the pearlite cluster boundary, the 偽 胃 lamellar interface, and the energy is consumed by multiple bending through the propagation path, which increases with the grain size of the original austenite. The change of quasi-static fracture toughness J is relatively small. However, the plastic influence zone at the notch front of impact toughness is much larger than the original austenite grain, and the large angle grain boundary will promote the crack turning and increase the propagation resistance, and increase the large angle grain boundary density in the plastic zone of the crack front to improve the impact energy. The impact toughness Ak decreases with the increase of grain size.
【作者單位】： 貴州大學(xué)材料與冶金學(xué)院;貴州省材料結(jié)構(gòu)與強度重點實驗室;
【基金】：國家自然科學(xué)基金(51461007;51361004) 貴州省重大應(yīng)用基礎(chǔ)研究項目([2014]2003)
【分類號】：TG142.1

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本文編號：2089263