Mn对22%Cr节Ni型双相不锈钢时效析出行为的影响研究
发布时间：2019-06-20 20:45
【摘要】：双相不锈钢由铁素体(δ)和奥氏体(γ)两相组成,兼有铁素体不锈钢和奥氏体不锈钢的优点,具有优良的力学和耐蚀的综合性能,目前被广泛应用于石油化工、海洋、造纸和能源等行业,在石油化工、造纸、食品加工等行业双相不锈钢需要在高温环境下服役,而双相不锈钢中加入较多的合金元素,在500-1000℃下等温过程中易产生σ相、氮化物、χ相等金属间相,对材料的冲击韧性和耐腐蚀性能有很大影响。镍在双相不锈钢中大量使用增加了成本,本文尝试用低成本的锰代替镍,研究锰对22%Cr双相不锈钢时效析出行为的影响,为节镍型双相不锈钢的开发以及高温环境下加工和使用提供参考。本论文从合金元素和时效温度对22%Cr双相不锈钢的组织和力学性能进行了系统的研究。采用光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、析出动力学和夏比冲击试验等分析仪器和手段,重点研究了 Mn对双相不锈钢500℃、600℃、700℃和800℃时效不同时间的析出行为的影响。本文主要研究结果如下:固溶处理结果表明:固溶温度从1040℃、1120℃升至1220℃,22%Cr双相不锈钢奥氏体相比例减小,冲击韧性下降,固溶温度1040℃时,实验钢两相比例较均衡,冲击韧性较好。时效析出行为研究结果表明:双相不锈钢时效析出行为主要发生在δ/γ晶界上和δ相内,时效温度升高可促进析出行为,不同时效温度析出相类型也不同:500℃时效温度下,析出相主要是为针状相和χ相,针状相随时效时间延长变得细小,最后完全转化为块状χ相;600℃时效温度下,析出相主要是χ相、σ相和γ2相,析出机制为:δ→2 + σ(χ),细小的χ相在晶界处最先析出,γ2相和σ相共析状析出相随后析出;700℃和800℃时效温度下,析出相主要是γ2相、σ相和M23C6碳化物,按照δ→γ2+ M23C6和δ→γ2 + σ的机制析出。锰元素对χ相和σ相的析出均有促进作用:500℃时效温度下,实验钢锰含量增加,χ相中锰含量递增,钼含量递减,锰原子替代钼原子改变了 χ相的晶格常数导致χ相与铁素体共格,使χ相可在500℃时效温度下大量析出并稳定存在;600℃时效温度下,χ相锰含量较低,锰元素更易富集于σ相中,促进σ相析出;700℃和800℃时效温度下,实验钢锰含量越高,M23C6碳化物析出越早,σ相析出提前,σ相最大析出量也越大。析出动力学结合冲击实验分析结果表明:锰含量和时效温度都会影响δ相分解动力学参数。相同时效温度下,锰含量增加,反应常数k和时间指数n均增大,δ相分解时间提前,分解速率加快;相同成分下,随着时效温度增加,k值显著增大,时效温度从600℃增至800℃,δ相分解时间提前。少量δ相分解对试样冲击韧性影响不大,δ相分解体积分数超过3%会导致试样的冲击韧性迅速降低。时效初期δ相分解数量较少,冲击韧性主要受双相不锈钢两相组织的影响,锰含量较高的试样奥氏体相比例较大,冲击韧性较好;时效中后期,试样韧性主要受σ相影响,锰含量较高的试样σ相数量更多,冲击韧性较差。
[Abstract]:The duplex stainless steel consists of two phases of ferrite and austenitic stainless steel, has the advantages of ferrite stainless steel and austenitic stainless steel, has excellent mechanical and corrosion-resistant comprehensive performance, and is widely used in the fields of petrochemical, ocean, paper and energy, in that proces of petrochemical, paper and food processing, the two-phase stainless steel needs to service in a high-temperature environment, and the two-phase stainless steel is added with more alloy elements, The impact toughness and the corrosion resistance of the material can be greatly affected. In this paper, the effect of manganese on the aging and precipitation behavior of 22% Cr duplex stainless steel is studied by using low-cost manganese instead of nickel, and the reference is provided for the development of the nickel-type duplex stainless steel and the processing and use in high-temperature environment. The microstructure and mechanical properties of 22% Cr duplex stainless steel were studied in this paper. The analytical instruments and methods such as optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), precipitation kinetics and Charpy impact test were used. The effects of Mn on the precipitation behavior of two-phase stainless steel 500 鈩，
本文编号：2503518
[Abstract]:The duplex stainless steel consists of two phases of ferrite and austenitic stainless steel, has the advantages of ferrite stainless steel and austenitic stainless steel, has excellent mechanical and corrosion-resistant comprehensive performance, and is widely used in the fields of petrochemical, ocean, paper and energy, in that proces of petrochemical, paper and food processing, the two-phase stainless steel needs to service in a high-temperature environment, and the two-phase stainless steel is added with more alloy elements, The impact toughness and the corrosion resistance of the material can be greatly affected. In this paper, the effect of manganese on the aging and precipitation behavior of 22% Cr duplex stainless steel is studied by using low-cost manganese instead of nickel, and the reference is provided for the development of the nickel-type duplex stainless steel and the processing and use in high-temperature environment. The microstructure and mechanical properties of 22% Cr duplex stainless steel were studied in this paper. The analytical instruments and methods such as optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), precipitation kinetics and Charpy impact test were used. The effects of Mn on the precipitation behavior of two-phase stainless steel 500 鈩，
本文编号：2503518
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