(1. 中國航發(fā)北京航空材料研究院 表面工程研究所, 北京 100095；
2. 中國航發(fā)北京航空材料研究院 航空材料先進腐蝕與防護航空重點實驗室, 北京 100095；
3. 中國航發(fā)四川燃氣渦輪研究院，成都 610500)
摘 要: 對GH4169合金中心孔板材試樣進行冷擠壓強化，研究了冷擠壓和(600 ℃, 500 h)熱時效對試樣在(600 ℃, 820 MPa, R=0.1, 三角波)條件下的低循環(huán)疲勞性能的影響。結(jié)果表明：冷擠壓后中值疲勞壽命估計量由原始狀態(tài)的7278周次提高到19536周次，提高了約2.5倍，顯著提高了高溫疲勞壽命，而熱時效后原始狀態(tài)疲勞壽命由7278周次降低到4717周次，降低了35.8%，發(fā)生了疲勞弱化。疲勞弱化的原因是熱時效使γ″強化相向δ相轉(zhuǎn)變，強化相含量減少，δ相數(shù)量增多且發(fā)生形態(tài)變化。熱時效后，原先冷擠壓表面殘余壓應力由-708 MPa降低到-483 MPa。仍然起到強化作用的穩(wěn)定部分殘余壓應力場與熱時效后強化相減少的弱化作用綜合影響，使得冷擠壓強化+熱時效后疲勞壽命(8188周次)較原始狀態(tài)壽命(7278周次)提高了12.5%。
關(guān)鍵字: 冷擠壓；熱時效；孔結(jié)構(gòu)；低循環(huán)疲勞；δ相轉(zhuǎn)變
（1. Surface Engineering Institution, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China;
2. Aviation Key Laboratory of Advanced Corrosion and Protection on Aviation Materials, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China;
3. AECC Sichuan Gas Turbine Establishment, Chengdu 610500, China）
Abstract:The GH4169 alloy center hole plate samples were cold-expanded, and the effects of cold expansion and (600 ℃, 500 h) thermal aging on the low-cycle fatigue performance under the conditions of 600 ℃, 820 MPa, R=0.1, and triangular wave were studied. The results show that the median fatigue life estimation increases from 7278 cycles in the original state to 19536 cycles after cold expansion, representing an increase of about 2.5 times and indicating that the cold expansion process significantly improves the high-temperature fatigue life. While the thermal aging process is subjected, the fatigue life decreases from 7278 cycles to 4,717 cycles. The 35.8% reduction indicates that fatigue weakening has occurred after thermal aging. The reason for fatigue weakening is that thermal aging transforms the γ" strengthening phase to δ phase, therefore the content of strengthening phase decreases while the number of δ phases increases and the morphology changes. Additionally after thermal aging, the original cold expansion surface residual compressive stress is reduced from -708 MPa to -483 MPa. The stable part of compressive residual stress profiles that still plays a role of strengthening, and the weakening effect of the reduction of the strengthening phase after thermal aging has a comprehensive effect, making the fatigue life of cold expansion and thermal aging (8188 cycles) increases by 12.5% compared to the original life (7278 cycles).
Key words: cold expansion; aging; hole structure; low-cycle fatigue; δ phase transformation
