低温条件下QTD900-8的力学性能研究
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摘要
以QTD900-8材料为研究对象,采用拉伸、冲击、布氏硬度测试以及扫描电镜的分析方法,研究其在低温条件下的力学性能和断口形貌特征,结果表明:(1)随着温度的降低,QTD900-8的力学性能变化很大,在-60℃时,相对于常温条件抗拉强度提高了19.8%,伸长率降低了33.0%,冲击韧度下降超过了70%,硬度提高了18.4%;(2)随着温度的降低,QTD900-8发生了韧性断裂、混合型断裂、脆性断裂变化的过程;(3)低温下,拉伸断裂过程中首先在石墨处产生裂纹,进而扩散至整个截面,导致材料断裂。
By using QTD900-8 material as investigation object,adopting tensile test,impact test,HB test and SEM analysis,the mechanical properties,fracture morphology characteristics of the material were investigated,the result showed:(1)With the decrease of temperature,the mechanical properties of QTD900-8 vary greatly:compared with normal temperature condition,at-60 ℃,the tensile strength was increased by 19.8%,the elongation decreased by 33.0%,the impact toughness decreased by more than 70%,the hardness elevated by 18.4%.(2)As the temperature drops,the process of ductile fracture,mixed mode fracture and brittle fracture occurred with QTD900-8.(3)At low temperature,cracks first occur in graphite in the process of tensile fracture,and then spread to the whole section,which led to the fracture of the material.
By using QTD900-8 material as investigation object,adopting tensile test,impact test,HB test and SEM analysis,the mechanical properties,fracture morphology characteristics of the material were investigated,the result showed:(1)With the decrease of temperature,the mechanical properties of QTD900-8 vary greatly:compared with normal temperature condition,at-60 ℃,the tensile strength was increased by 19.8%,the elongation decreased by 33.0%,the impact toughness decreased by more than 70%,the hardness elevated by 18.4%.(2)As the temperature drops,the process of ductile fracture,mixed mode fracture and brittle fracture occurred with QTD900-8.(3)At low temperature,cracks first occur in graphite in the process of tensile fracture,and then spread to the whole section,which led to the fracture of the material.
引文
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[3]彭凡,尤国庆,郭亮.QT900-2高强韧厚大断面球墨铸铁的研究[J].现代铸铁,2018,(01):33-37.
[4]杨明月,叶小龙,麻先银.球墨铸铁金相组织缺陷原因及防止方法概述[J].现代铸铁,2017,(03):65-70.
[5]Matti Johansson. Austempered Ductile Iron(ADI)for HeavyLoaded Applications[A].奥贝球铁(ADI)国际学术报告会论文集[C].武汉:湖北省机电研究设计院,2000:1-31.
[6]邓宏运,王春景,章舟.等温淬火球墨铸铁的生产及应用实例[M].北京:化学工业出版社,2009:58-66.
[7]唐才宇,姜珂,曲迎东.一种耐低温奥氏体球铁的低温性能和表面强化分析[J].铸造,2014,(06):532-535.
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