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921.
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923.
In this work,the cause of the cold-strip breakage of SUS445J2 ultra-pure ferritic stainless steel was investigated using optical microscopy,energy dispersive spectroscopy,and electron backscatter diffraction technique.Results show that during cold rolling,the breakage of the stainless steel strip was mainly caused by massive niobium-rich(Nb-rich)carbides present in the center of the strip.Furthermore,cracks initiated at these carbides in the central layer.The massive carbide precipitates resulted from the segregation and enrichment of Nb,titanium(Ti),and carbon(C)in the central layer during the subsequent solidification stage of SUS445J2 stainless steel.Additionally,the banded structure and coarse ferrite grains in the central layer reduced the plasticity of the material,causing cracks to propagate along these grains and finally leading to cold-strip breakage.By reducing the solidification cooling rate of the billet,increasing the pouring temperature,discretizing Nb,Ti,and C enrichment via electromagnetic stirring,and forming equiaxed crystals in the central layer,the precipitation of harmful massive Nb-rich carbides in the central layer could be effectively avoided. 相似文献
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926.
《Journal of the European Ceramic Society》2014,34(16):4137-4144
Al2O3 particle-reinforced Cr2AlC in situ composites were successfully fabricated from powder mixtures of Cr3C2, Cr, Al, and Cr2O3 by a reactive hot-pressing method at 1400 °C. A possible synthesis mechanism was proposed to explain the formation of the composites in which Al2O3 was formed by the aluminothermic reaction between Al and Cr2O3, meanwhile, Cr3C2, Al, together with Cr reacted to form Cr2AlC in a shortened reaction route. The effect of Al2O3 addition on the microstructure and mechanical properties of Cr2AlC/Al2O3 composites was investigated. The results indicated that the as-sintered products consisted of Cr2AlC matrix and Al2O3 reinforcement, and the in situ formed fine Al2O3 particles dispersed at the matrix grain boundaries. The flexural strength and Vickers hardness of the composites increased gradually with increasing Al2O3 content. But the fracture toughness peaked at 6.0 MPa m1/2 when the Al2O3 content reached 11 vol.%. The strengthening and toughening mechanism was also discussed. 相似文献
927.
阐述了锅炉及供热系统给水除氧的重要性,对常用锅炉给水除氧方法进行简要分析总结,在选择锅炉给水除氧方式时,应结合各种除氧方式的特点,采用适合本供热系统的最佳除氧方式。 相似文献
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929.
Sadanand V. Deshpande Jeffrey L. Dupuie Erdogan Gulari 《Advanced functional materials》1996,6(3):135-146
We have applied the novel method of hot filament-activated chemical vapour deposition (HFCVD) for low-temperature deposition of a variety of nitride thin films. In this paper the results from our recent work on aluminium, silicon and titanium nitride have been reviewed. In the HFCVD method a hot tungsten filament (1500–1850°C) was utilised to decompose ammonia in order to deposit nitride films at low substrate temperatures and high rates. The substrate temperatures ranged from 245 to 600°C. The film properties were characterised by a number of analytical and optical methods. The effect of various deposition conditions on film properties was studied. All the films obtained were of high chemical purity and had very low or no detectable tungsten contamination from the filament metal. 相似文献
930.
介绍了热连轧机中热卷箱的速度控制及其与轧机和辊道的速度匹配关系。热卷箱位于热连轧生产线粗轧机和精轧机中间的工艺设备,它将粗轧中间坯卷成热钢卷然后再开卷送入飞剪及精轧机。生产过程中热卷箱需要与粗轧机形成连轧连卷,又要与精轧机形成连开连轧的工况。处理好热卷箱与轧机的速度匹配关系对稳定生产和提高产品质量至关重要。 相似文献