再结晶厚度对定向凝固DZ125合金蠕变性能的影响
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摘要
柱状晶DZ125合金在铸态条件下进行不同强度的表面吹砂,然后进行标准热处理获得不同厚度的再结晶层,并测定出合金的蠕变寿命,对比分析再结晶及其厚度对合金蠕变性能的影响,采用扫描电镜对铸态、热处理态和蠕变断裂后合金的微观组织进行观察,试验结果表明:柱状晶DZ125合金在不同吹砂强度条件下,热处理后合金表面发生再结晶厚度不同,随吹砂强度的增大再结晶层的厚度增大。铸态DZ125柱状晶合金中的碳化物呈片状、条状或颗粒状,经标准热处理后合金中的碳化物部分发生溶解,片状碳化物尺寸减小,碳化物表面出现孔洞,条状碳化物转变为颗粒状,原有颗粒状碳化物尺寸降低。再结晶后,晶界析出少量颗粒状碳化物。具有不同再结晶厚度的2和4 mm片状试样,在980℃,235 MPa条件下的蠕变寿命相当,与未发生再结晶的柱状晶合金相比寿命降低30%。蠕变期间再结晶晶界碳化物发生了积聚和长大,这有利于提高再结晶晶界强度。蠕变期间断裂裂纹主要沿与应力轴垂直的再结晶晶界萌生,在柱状晶合金内部也存在裂纹萌生点。再结晶晶粒内发生了γ′相筏形化,说明柱状晶再结晶晶界虽然弱化了合金的蠕变强度,但其本身也具有一定的强度。
The surface of as-cast columnar crystal DZ125 alloy was blew sand followed by standard heat treatment process to obtain the recrystallization layers with different thickness, and the creep life of the alloy was measured. The effect of recrystallization and its thickness on the creep properties of the alloy was analyzed. The microstructure of the alloy was observed by scanning electron microscope. The results show that after heat treatment the thickness of the recrystallization layer on the surface of the columnar crystal DZ125 alloy is different at varied sand blowing intensity; with the sand blowing intensity increasing, the recrystallization layer thickness increases. The carbide in the as cast DZ125 columnar crystal alloy is slice, strip or grain, and the carbide after the standard heat treatment is partly dissolved, the size of the slice is reduced, and holes appear on the surface of slice carbide. Strip carbides turn into grains, and the original grain size declines. A small amount of grain carbides are precipitated around the grain boundaries after recrystallization. The creep lives of 2 mm and 4 mm thick samples with different recrystallization thickness are roughly equal to each other under the condition of 980 °C and 235 MPa, while decreased by 30% compared to that of the columnar crystal alloy without recrystallization. During the creep, the carbides in the grains are accumulated and grow around the grain boundary, which is beneficial to improve the strength of grain boundary. During creep the crack initiation is mainly along with the recrystallization grain boundary which is vertical to the stress axis. Crack initiation points also exist in the internal of the columnar crystal alloy. The γ′ phase rafted in recrystallization grains indicates that the grain boundaries of recrystallization have certain strength, although they weaken the creep strength of the alloy.
The surface of as-cast columnar crystal DZ125 alloy was blew sand followed by standard heat treatment process to obtain the recrystallization layers with different thickness, and the creep life of the alloy was measured. The effect of recrystallization and its thickness on the creep properties of the alloy was analyzed. The microstructure of the alloy was observed by scanning electron microscope. The results show that after heat treatment the thickness of the recrystallization layer on the surface of the columnar crystal DZ125 alloy is different at varied sand blowing intensity; with the sand blowing intensity increasing, the recrystallization layer thickness increases. The carbide in the as cast DZ125 columnar crystal alloy is slice, strip or grain, and the carbide after the standard heat treatment is partly dissolved, the size of the slice is reduced, and holes appear on the surface of slice carbide. Strip carbides turn into grains, and the original grain size declines. A small amount of grain carbides are precipitated around the grain boundaries after recrystallization. The creep lives of 2 mm and 4 mm thick samples with different recrystallization thickness are roughly equal to each other under the condition of 980 °C and 235 MPa, while decreased by 30% compared to that of the columnar crystal alloy without recrystallization. During the creep, the carbides in the grains are accumulated and grow around the grain boundary, which is beneficial to improve the strength of grain boundary. During creep the crack initiation is mainly along with the recrystallization grain boundary which is vertical to the stress axis. Crack initiation points also exist in the internal of the columnar crystal alloy. The γ′ phase rafted in recrystallization grains indicates that the grain boundaries of recrystallization have certain strength, although they weaken the creep strength of the alloy.
引文
[1]Shi Changxu(师昌绪),Zhong Zongyong(仲增墉).Acta Metallurgica Sinica(金属学报)[J],2010,46(11):1281
[2]Hu Zhuangqi(胡壮麒),Liu Lirong(刘丽荣),Jin Tao(金涛),Sun Xiaofeng(孙晓峰).Aeroengine(航空发动机)[J],2005,31(3):1
[3]Zhang Weiguo(张卫国),Liu Lin(刘林),Zhao Xinbao(赵新宝)et al.Foundry(铸造)[J],2009,58(1):1
[4]Whitesell H,Overfelt R A.Mate Sci Eng A[J],2001,318:264
[5]Chu Zhaokuang(储昭贶),Yu Jinjiang(于金江),Sun Xiaofeng(孙晓峰)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2009,38(5):834
[6]Agnieszka Szczotok,Janusz Szala,Jan Cwajna et al.Materials Characterization[J],2006,56:348
[7]Bae J S,Lee J H,Kim S S et al.Scripta Materialia[J],2001,45:503
[8]Wang Changshuai(王常帅),Zhang Jun(张军),Liu Lin(刘林)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2011,40(2):307
[9]Zhang Mingjun(张明俊),Peng Zhijiang(彭志江),Sun Baocai(孙宝才)et al.Foundry(铸造)[J],2015,64(5):459
[10]Tao Chunhu(陶春虎),Zhang Weifang(张卫方),Li Yunju(李运菊)et al.Failure Analysis and Prevention(失效分析与预防)[J],2006,1(4):1
[11]Tao Chunhu(陶春虎),Yan Minggao(颜鸣皋),Zhang Weifang(张卫方)et al.Journal of Materials Engineering(材料工程)[J],2003(Sl):15
[12]Zhang Weifang(张卫方),Gao Wei(高威),Zhao Aiguo(赵爱国)et al.Materials for Mechanical Engineering(机械工程材料)[J],2003,27(9):48
[13]Zhang Weifang,Li Yunju,Liu Gaoyuan et al.Engineering Failure Analysis[J],2004,11(3):429
[14]Pu Sheng(濮晟),Xie Guang(谢光),Zheng Wei(郑伟)et al.Acta Metallurgica Sinica(金属学报)[J],2015,51(2):239
[15]Sun Chuanqi(孙传祺),Tao Chunhu(陶春虎),Xi Niansheng(习年生)et al.Materials for Mechanical Engineering(机械工程材料)[J],2001,25(8):4
[2]Hu Zhuangqi(胡壮麒),Liu Lirong(刘丽荣),Jin Tao(金涛),Sun Xiaofeng(孙晓峰).Aeroengine(航空发动机)[J],2005,31(3):1
[3]Zhang Weiguo(张卫国),Liu Lin(刘林),Zhao Xinbao(赵新宝)et al.Foundry(铸造)[J],2009,58(1):1
[4]Whitesell H,Overfelt R A.Mate Sci Eng A[J],2001,318:264
[5]Chu Zhaokuang(储昭贶),Yu Jinjiang(于金江),Sun Xiaofeng(孙晓峰)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2009,38(5):834
[6]Agnieszka Szczotok,Janusz Szala,Jan Cwajna et al.Materials Characterization[J],2006,56:348
[7]Bae J S,Lee J H,Kim S S et al.Scripta Materialia[J],2001,45:503
[8]Wang Changshuai(王常帅),Zhang Jun(张军),Liu Lin(刘林)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2011,40(2):307
[9]Zhang Mingjun(张明俊),Peng Zhijiang(彭志江),Sun Baocai(孙宝才)et al.Foundry(铸造)[J],2015,64(5):459
[10]Tao Chunhu(陶春虎),Zhang Weifang(张卫方),Li Yunju(李运菊)et al.Failure Analysis and Prevention(失效分析与预防)[J],2006,1(4):1
[11]Tao Chunhu(陶春虎),Yan Minggao(颜鸣皋),Zhang Weifang(张卫方)et al.Journal of Materials Engineering(材料工程)[J],2003(Sl):15
[12]Zhang Weifang(张卫方),Gao Wei(高威),Zhao Aiguo(赵爱国)et al.Materials for Mechanical Engineering(机械工程材料)[J],2003,27(9):48
[13]Zhang Weifang,Li Yunju,Liu Gaoyuan et al.Engineering Failure Analysis[J],2004,11(3):429
[14]Pu Sheng(濮晟),Xie Guang(谢光),Zheng Wei(郑伟)et al.Acta Metallurgica Sinica(金属学报)[J],2015,51(2):239
[15]Sun Chuanqi(孙传祺),Tao Chunhu(陶春虎),Xi Niansheng(习年生)et al.Materials for Mechanical Engineering(机械工程材料)[J],2001,25(8):4