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非等溫回歸再時效對7055鋁合金中厚板的厚向組織及性能均勻性的影響
發(fā)布人：上海艾荔艾金屬材料有限公司bt990.com.cn
更新時間：2015-12-03
通過力學性能測試、腐蝕性能測試、透射電鏡(TEM)觀察和動力學計算研究回歸加熱、冷卻速率的匹配對回歸再時效(RRA)態(tài)7055鋁合金中厚板析出組織均勻性及厚向性能的影響。
非等溫回歸再時效對7055鋁合金中厚板的厚向組織及性能均勻性的影響Effect of non-isothermal retrogression and re-ageing onthrough-thickness homogeneity of microstructure and properties in7055 aluminum alloy medium thick plate
通過力學性能測試、腐蝕性能測試、透射電鏡(TEM)觀察和動力學計算研究回歸加熱、冷卻速率的匹配對回歸再時效(RRA)態(tài)7055鋁合金中厚板析出組織均勻性及厚向性能的影響。結(jié)果表明：固定回歸加熱速率，合金的強度、斷裂韌性和耐腐蝕性能的均勻性及厚向析出組織的均勻性隨著回歸冷卻速率的降低而提高。但是慢速回歸降溫增加合金析出相的粗化程度，導致合金強度下降。綜合考慮性能及均勻性，建立的包含空冷降溫處理以補償7055鋁合金中厚板厚向組織均勻性的“非等溫回歸再時效”制度為(105 ℃，24 h)+(190 ℃，70 min)(升溫速率3 ℃/min，70 min包含加熱時間)+(空冷25 min至120 ℃)+(120 ℃，24 h)。經(jīng)非等溫回歸再時效處理后，7055鋁合金板材心層的抗拉強度、斷裂韌性及剝落腐蝕等級分別為619 MPa、24.7 MPa？m1/2和EB-，其強度的厚向均勻性比常規(guī)回歸再時效處理的提高約50%。
The effect of matching relationship between retrogression heating and cooling rate on the microstructure homogeneity and through-thickness properties of medium-thick 7055 aluminum alloy plate was investigated by mechanical properties test, corrosion resistance test, transmission electron microscope(TEM) observation and kinetics calculation. The results show that, the through-thickness of strength, fracture toughness, corrosion resistance and microstructure homogeneity increase with the decrease of retrogression cooling rate when heating rate is fixed. However, the slow retrogression cooling rate increases the coarsening degree of precipitates, which results in the deterioration of strength. Considering the compositive request to properties and homogeneity, the “non-isothermal retrogression and re-ageing” temper based on the air cooling treatment to through-thickness homogeneity was established as (105 ℃, 24h)+(190 ℃, 70 min) (heating rate 3 ℃/min, 70 min including heating time)+(air cooling 25 min to 120 ℃)+( 120 ℃, 24 h). After “non-isothermal retrogression and re-ageing” treated, the tensile strength, fracture toughness and exfoliation corrosion resistance level are 619 MPa, 24.7 MPa？m1/2?and EB-, respectively. The through-thickness homogeneity of strength increases by 50% when compared to that of the conventional RRA treatment.
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