采用光学显微镜、扫描电子显微镜及X射线衍射等手段并通过显微硬度和冲击实验,研究了Supre304H钢经750~1350℃时效后的微观组织和性能.结果表明:高温时效后Super304H钢的微观组织为γ相+析出相;随时效温度的不同,基体晶粒尺寸及析出相的种类、分布发生不同的变化.在750℃左右因微细沉淀强化及细晶组织使得显微硬度达到最大值,而后随温度升高以及析出相、晶粒尺寸与固溶元素的变化,显微硬度呈现先快速下降后缓慢下降的趋势;时效试样的冲击功值随温度升高在850℃左右,由于M23C6沿晶界大量析出导致晶界脆化而达到最低值,后又因析出相的再溶解致使晶界脆化效果趋弱而逐渐升高.
Abstract
The microstructure and property of novel austenitic heat-resistance steel Super304H after being aged at 750-1350℃ were investigated by the means of optical microscope,scanning electron microscopy(SEM),X-ray diffraction(XRD),as well as hardness testing and impact test.The experimental results indicated that the microstructure of super304H after being aged included γ-phase and precipitated phase.With the variation of aging temperature,the grain size of matrix and the type of precipitated phase will be changed.When the sample was aged at 750℃,the hardness reached the maximum value due to the precipitation strengthening and fine microstructure.With increasing the aging temperature beyond 750℃,the microhardness rapidly decreased at first and then decreased slowly because of the variation of precipitated phase,grain size and solid solution elements.The impact energy value of aged sample increased before being aged at 850℃,and reached minimum when aged at 850℃ due to M23C6 precipitated along grain boundary and caused embrittlement.The impact energy increased again with increasing aging temperature,because the precipitated phase redissolved and eliminating the grain boundary embrittlement.
关键词
Super304H钢 /
时效处理 /
析出相 /
组织 /
性能
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Key words
Super304H steel /
aging treatment /
precipitated phase /
microstructure /
property
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中图分类号：
TG142.1
TG142.7
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参考文献
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脚注
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基金
山东省电力集团公司重点科技项目(2007A-47)
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