共查询到17条相似文献,搜索用时 62 毫秒
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通过热模拟试验研究了不同热输入条件下S355J2钢粗晶热影响区M-A组元的体积分数及形态对韧性的影响。试验结果表明,热循环峰值加热温度Tmax一定,粗晶热影响区M-A组元的体积分数随冷却时间t8/5的延长而增大,在t8/5为60s时M-A组元的体积分数增加的幅度最大;随着t8/5的延长,M-A组元的形态由颗粒状向长条状和块状转变,在Tmax较大、t8/5较长时,M-A组元的形态将趋向于形成细长条状和块状;粗晶热影响区的韧性随M-A组元体积分数的增大而降低,细长条状和块状的M-A组元对韧性的影响最大 相似文献
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利用模拟试验机对Q460耐候钢不同热输入条件下的焊接粗晶热影响区进行模拟,分析粗晶热影响区中显微组织及其中马氏体-奥氏体(M-A)组元的数量、形态、分布及大小对韧性的影响。结果表明,t8/5较小时,组织由板条贝氏体和粒状贝氏体构成,M-A组元尺寸较小;t8/5为100 s时,组织中板条贝氏体量逐渐减小,粒状贝氏体含量逐渐增多,M-A呈块状,尺寸变大,有效晶粒尺寸增加,韧性降低;当t8/5达到150~200 s时,即使组织粗大,M-A组元的量有所减少,出现部分残留奥氏体,韧性也会增加。 相似文献
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800 MPa级低合金钢焊接热影响区韧性的研究 总被引:19,自引:0,他引:19
利用Gkeble-1500热模拟机对弛豫-析出-控制相变(RPC)得到的低合金钢进行不同焊接工艺下的热模拟实验,研究了激光焊接条件下热影响区粗晶区(CGHAz)组织、韧性及其变化规律.结果表明,CGHAz组织为粒状贝氏体;CGHAZ韧性随800-500℃冷却时间£8/5的增大先增大然后减小,当t8/5为3—8s时,-40℃ CGHAZ冲击吸收功远高于母材的冲击吸收功,表明在合适的激光焊接条件下,激光焊接CGHAZ可获得很好低温韧性.考虑马氏体-奥氏体(M—A)组元平均宽度、总量、分布、形态对粒状贝氏体韧性的综合影响,提出了M—A组元韧性参数的概念,并利用M—A组元韧性参数阐述了CGHAZ韧性随t8/5的变化规律. 相似文献
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用热模拟方法研究了WB36钢(15NiCuMoNb5)临界再热粗晶区(IRCGHAZ)组织特征及性能,分析组织转变过程及M-A组元形成原因,揭示了1RCGHAZ脆化机理。结果表明,IRCGHAZ保持粗大的板条状马氏体组织特征,形成了密集的M-A组元,其中条状M-A组元分布于马氏体板条间,而在原始奥氏体晶界形成链状M-A组元。与一次粗晶区(CGHAZ)、二次粗晶区及过临界再热粗晶区(SCCGHAZ)相比,IRCGHAZ的韧性最低,它将导致接头的局部脆化现象。IRCGHAZ脆化的主要原因是存在于晶内的条状M-A组元,而不是分布于晶界的粒状M-A组元,这是由于条状M-A组元比颗粒状M-A组元更容易引起解理断裂。 相似文献
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采用热模拟试验研究了Nb对不同焊接热循环时粗晶热影响区组织、性能及转变动力学的影响.试验结果表明,在全部热输入下,不含Nb钢韧度均高于含Nb钢韧性,但大热输入(60~100kJ/cm)时韧性值相差较大,差值最小为60 kJ/cm时相差153 J,小热输入(40~30J/cm)时韧性值相差较小,差值最大为30 kJ/cm时相差68 J.从不同热输入时膨胀试验分析可知,含Nb钢转变开始温度Ar 3比不含Nb钢低约15~30℃,大热输入时固溶Nb抑制铁素体转变,促进粒状贝氏体形成,严重恶化韧性,小热输入时含Nb钢低碳自回火马氏体数量较多,但韧度较好,与以细板条贝氏体组织为主的不含Nb钢相比韧性仅有小幅下降. 相似文献
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Based on welding thermal simulation on Nb-microalloyed X80 pipeline steel using Gleeble-3500 thermal simulation equipment,microstructure and impact toughness in coarse grain heat-affected zone (CGHAZ) ... 相似文献
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利用 thermol-cal 软件获得一定成分体系下铁路货车用 12%Cr 铁素体不锈钢的相图,结合相图对 12%Cr 铁素体不锈钢的焊接过程进行分析.利用光学显微镜、扫描电镜分析 12%Cr 铁素体不锈钢的焊接热影响区为铁素体和马氏体以及碳、氮化物组成的粗晶区和细晶区两部分.结果表明,铁素体晶粒的尺寸与马氏体的含量是影响热影响粗晶区韧性的主要因素.当母材中的碳、氮化物颗粒尺寸在 2~5μm 时,具有最优的冲击性能;当母材中碳+氮含量为 0.02% 左右时,在文中试验条件下粗晶区的马氏体含量为 40%,焊接接头粗晶区具有 -22 ℃的最低韧脆转变温度.Abstract: The transformation temperature phase diagram of 12% chromium steel is obtained by using Thermal-cal software. Process of welding 12% chromium stainless steel is analysed with the phase transformation temperature scope. The heat-affected zone (HAZ) of the weld joints is observed with optic microscope and scanning electronic microscope, which the microstructure consists of ferrite, martensite, coarse grain heat-affected zone (CGHAZ), fine grain heat-affected zone (FGHAZ) and Ti(C/N). The key elements that affect toughness of CGHAZ are ferritic grain size and martensitic content. The base material has the best impact toughness when grain size of Ti(C/N) reaches 2-5μm. The lowest ductility-brittle transition temperature in CGHAZ is -22 ℃ when content of carbon plus nitrogen in base material is about 0.02% and martensitic content in CGHAZ is 40% under some certain welding procedure. 相似文献
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Effect of Zr-Ti combined deoxidation on impact toughness of coarse-grained heat-affected zone with high heat input welding 下载免费PDF全文
In this study, the effects of Zr-Ti combined deoxidation and AI deoxidation on the impact toughness of coarse- grained heat-affected zone in high-strength low-alloy steels were investigated. More fine oxides were formed in the Zr-Ti-killed steel than in Al-killed steel. It was also found that more acicular ferrite grains were formed in the coarse-grained heat-affected zone in the Zr-Ti-killed steel than in Al-killed steel. The impact toughness of coarse-grained heat-affected zone of Zr-Ti-kiUed steel was higher than that of Al-killed steel. The good impact toughness was attributable to the pinning effect of fine oxides and the formation of acicular ferrite grains on fine oxides. 相似文献
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通过光学显微镜和电子显微镜对比分析了Zr-Ti复合脱氧和传统Al脱氧两种脱氧方式低合金高强度钢在大线能量埋弧焊条件下焊接热影响区粗晶区的组织,研究了两种脱氧方式对粗晶区低温冲击韧性的影响.结果表明:经过Zr-Ti复合脱氧处理后,低合金高强度钢中形成了许多细小弥散的Zr-Ti复合氧化物粒子,这些粒子具有高温稳定性,在焊接过程中起到了钉扎焊接热影响区粗晶区奥氏体晶界移动来抑制晶粒长大和促进针状铁素体形成,所以在较大的埋弧焊焊接线能量(51 kJ/cm)条件下改善了钢板的低温冲击韧性. 相似文献
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The influence of the secondary thermal cycle on the microstructure of coarse grain heat-affected zone in an X100 pipeline steel was investigated by means of a thermal simulation technique and microscopic analysis method. The property of coarse grain heat-affected zone was characterized by Charpy V-Notch impact properties testing. The results indicated that the experimental steel exhibited local brittleness of intercritically reheated coarse-grained heat-affected zone when the peak temperature of secondary thermal cycle was in the range of two phases region (α and γ). There were two main reasons for the local brittleness. The first was that the microstructures of intercritically reheated coarse-grained heat-affected zone were not fined although partial grain recrystallization occurred. The second was that M-A islands, which had the higher content, larger size and higher hardness, existed in intercritically reheated coarse-grained heat-affected zone. 相似文献
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