Effects of Ni and Heat Treatment on Long-term Creep Strength of Precipitation Strengthened 15Cr Ferritic Heat Resistant Steels
Effects of Ni and Heat Treatment on Long-term Creep Strength of Precipitation Strengthened 15Cr Ferritic Heat Resistant Steels
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DOI：
10.2355/isijinternational.45.1747
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发表时间：
2005-11
影响因子：
1.8
通讯作者：
Y. Toda;Mitsuyoshi Iijima;H. Kushima;K. Kimura;F. Abe
中科院分区：
文献类型：
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作者：
Y. Toda;Mitsuyoshi Iijima;H. Kushima;K. Kimura;F. Abe
研究了镍含量和热处理条件对沉淀强化15Cr铁素体钢蠕变强度的影响。通过固溶处理和水淬，15Cr铁素体钢的蠕变强度得到了显著提高。然而，从长远来看，镍对水冷钢蠕变强度的不利影响是明显的。随镍含量的增加，马氏体相的体积分数增加，在两个空冷和水淬火钢。在相同的镍含量下，水淬钢中马氏体相的体积分数小于水冷钢中马氏体相的体积分数。细颗粒，小于500 nm，均匀地沉淀在铁素体相的水淬火钢。另一方面，在马氏体相内稀疏地析出了尺寸为1 μm的粗大块状颗粒，加速了马氏体组织的回复。随炉冷和镍的加入，马氏体相体积分数增加，钢的蠕变强度降低。马氏体相较低的蠕变强度和显微组织稳定性归因于较少的沉淀强化。为了使这种钢能够投入实际使用，需要通过优化化学成分和热处理条件来抑制由添加镍引起的马氏体相的形成。
The effects of nickel content and heat treatment conditions on the creep strength of precipitation-strengthened 15Cr ferritic steel were investigated. The creep strength of the 15Cr ferritic steel was drastically improved by solution treatment and water quenching. However, over the long term, the detrimental effect of nickel on the creep strength was pronounced for water-quenched steels. The volume fraction of martensite phase increased with increased nickel content in both the furnace-cooled and water-quenched steels. The volume fraction of martensite phase in the water-quenched steel was smaller than that in the furnace-cooled type, even for the same nickel content. Fine particles, smaller than 500 nm, were precipitated homogeneously within the ferrite phase of the water-quenched steel. On the other hand, coarse block-like particles 1 μm in size were precipitated sparsely within the martensite phase, and the recovery of martensitic microstructure was accelerated. The creep strength of the steels decreased with increased volume fraction of the martensite phase caused by furnace cooling and nickel addition. The lower creep strength and microstructural stability of the martensite phase is attributable to less precipitation strengthening. To enable this steel to be put to practical use, it will be necessary to suppress the formation of the martensite phase caused by addition of nickel by optimizing the chemical composition and heat treatment conditions.