RRA热处理喷射成形7075高强铝合金应力腐蚀特征

Spray formed 7xxx aluminum alloys have broad prospects due to these strengths could be reached 800 MPa. But the study on stress corrosion cracking (SCC) of the alloys had not been reported. Because of the solid solubility, the second phase and grain boundary characteristics of the spray formed alloys are significantly different from traditional as-cast alloys. In addition the reticular dislocations have been discovered in stress corrosion tests. The SCC process and performance will be affected by aforementioned factors. So this project main content are (1) the study on microstructure of the spray formed 7075 alloy during RRA treatment with kinetics; (2) the influence on SCC property of solid solubility and precipitates of the alloy; (3) the effect on SCC property of the second phase and precipitate free zone on grain boundary; (4) the influence on formative factor of reticular dislocations and SCC property of dislocation and stacking fault. The possible innovation points are: (1) the analysis on the SCC property and characteristic of the spray formed 7075 alloy with the particularity of microstructure; (2) the mastery on dynamics of microstructure evolution of the spray formed 7075 alloy during RRA treatment; (3) the forming of reticular dislocations. The scientific significances are to lay the foundation of controlling and optimization on SCC property of the spray formed 7075 alloy, to provide the basis for RRA treatment on the alloy, to reveal the microcosmic essence of reticular dislocations and regularity of SCC property.

喷射成形7xxx铝合金强度可达800MPa，应用前景广阔，但对其应力腐蚀断裂（SCC）性能和特征的研究几乎未见报道，由于喷射态合金在固溶度、第二相、晶界特征等与传统铸态合金差异显著，且应力腐蚀测试组织中首次发现了网状位错，影响应力腐蚀断裂过程及性能，故拟开展项目研究，主要内容：(1)RRA处理的喷射合金微观组织演变动力学的研究；(2)固溶度、析出相等晶内组织对SCC的影响；(3)第二相、无析出带等晶界组织对SCC的影响；(4)位错、层错等对网状位错成因及其对SCC的影响。可能的创新点：(1)从微观组织的特殊性分析喷射7075合金的SCC性能和特征；(2)掌握RRA处理下喷射态合金微观组织演变动力学机制；(3)揭示网状位错形成的原因。其科学意义为：为喷射成形7075合金SCC性能控制及优化奠定基础，为该合金RRA工艺优化提供依据，可揭示出网状位错形成的微观本质及其对SCC的影响。

喷射成形7xxx铝合金强度可达800MPa，应用前景广阔，但对其应力腐蚀断裂（SCC）性能和特征的研究几乎未见报道，由于喷射态合金在固溶度、第二相、晶界特征等与传统铸态合金差异显著，且应力腐蚀测试组织中首次发现了网状位错，影响应力腐蚀断裂过程及性能，故拟开展项目研究。.主要内容为RRA处理的喷射合金微观组织演变动力学的研究；固溶度、析出相等晶内组织对SCC的影响；第二相、无析出带等晶界组织对SCC的影响；位错、层错等对网状位错成因及其对SCC的影响。.创新点为从微观组织的特殊性分析喷射7075合金的SCC性能和特征；掌握RRA处理下喷射态合金微观组织演变动力学机制；揭示网状位错形成的原因。.其科学意义表现为能更好的掌握该合金晶内、晶界组织演变，为喷射成形7075合金SCC性能控制及优化奠定基础；可以为RRA热处理工艺优化提供依据；揭示喷射成形 7075合金网状位错这一新现象的微观本质，能更好掌握网状位错对SCC性能的影响规律。