溶质元素对X80管线钢碳氮化物析出行为的影响

为了明晰X80管线钢凝固过程中析出物粒子析出规律。采用Thermo-calc软件对X80管线钢凝固过程中奥氏体、铁素体相转变温度,析出物类型,析出物开始析出温度与析出相最大质量分数进行热力学分析。计算结果表明:X80管线钢凝固过程析出相主要包括MnS相、AlN相、铁素体相及奥氏体相、富钛相碳氮析出相、富铌相碳氮析出相与碳化钒析出相。富钛相碳氮析出相析出温度为1 390℃,质量分数为1.2×10~(-4),析出相随C元素和Nb元素的含量增加而受到抑制。N元素和Ti元素含量增加会促进富钛相碳氮析出相生成,V元素质量分数增量对富钛相碳氮化物无明显规律。富铌相碳氮析出相在1 110℃析出,质量分数为1.3×10~(-3),随C元素和Nb元素的含量增加,促进富铌相碳氮析出相析出。增加N元素与Ti元素含量抑制富铌相碳氮析出相析出,V元素对富铌相碳氮化物无明显影响规律。碳化钒析出相析出温度为596℃,析出相质量分数为4.59×10~(-5),增加C元素和V元素含量利于碳化钒相析出,Nb元素含量增加对碳化钒相起到一定抑制作用。     

高Ti-Q550钢中Nb、Ti第二相的析出行为

 采用Thermo-Calc软件、热模拟及扫描电镜研究高Ti-Q550钢中微合金的析出规律。采用Thermo-Calc软件计算不同温度下Nb、Ti的析出规律,钛含量对钢中Nb、Ti析出规律及A3的影响。采用热模拟和扫描电镜研究钢中铌相的析出温度。计算结果表明,钛相的析出温度为1498℃,铌相析出温度为1251℃;随着钢中钛含量的增加,(Nb,Ti)C相析出温度和A3温度升高,但铌在钢中的固溶量降低;当钛的质量分数小于0. 08%时,Ti(N,C)相析出温度随钛含量增加而升高,但当钛的质量分数大于0. 08%时,相析出温度基本不变,钛在钢中的固溶量随钛含量增加而增加。     

镍基高温合金GH4706析出相的热力学计算与分析

应用Thermo-Calc热力学计算软件,模拟元素含量及热处理温度对镍基高温合金GH4706平衡相析出规律的影响。结果表明:平衡析出相的种类和析出温度范围与微观组织观测和差热分析的实验结果基本一致。MC碳化物的初始析出温度随Nb、Ti含量增加而降低,而析出量主要受C含量影响;η相初始析出温度与析出量随Ti含量增加而增大,受Nb、Fe影响较小;γ'相初始析出温度与析出量随Al含量增加而升高,受Ti、Nb含量影响较小;合金凝固过程中Nb、Ti会产生显著正偏析,Cr产生负偏析;Nb、Ti含量增加提高合金初熔点,降低合金的终熔点,使凝固温度范围变窄。     

取向硅钢热力学平衡析出相的计算和分析

为了提高取向硅钢磁性能的稳定性,采用Thermo-Calc软件系统分析了取向硅钢基本合金元素C、Si、Mn、S、Al、N对γ相的转变温度、最大含量、最大含量对应温度,AlN和MnS固溶析出转变温度以及最大析出量的影响。计算结果表明：C含量增加,γ相的转变温度升高、最大含量增加、最大含量对应的温度也升高;Si含量增加,γ相的转变温度降低、最大含量减少、最大含量对应的温度降低;MnS相最大析出量主要受S含量的影响;AlN相最大析出量随N含量增加而大幅增加。     

Nb和V对1Cr16Co5Ni2Mo1WVNbN钢中析出相影响的模拟计算

运用Thermo-Calc软件对650℃时钢中的平衡析出相进行了模拟计算,研究了钢中Nb、V含量的变化对析出相影响的变化规律。计算结果表明:650℃时钢中的主要平衡析出相为Laves相、M_(23)C_6、MX和Z相。随着Nb含量的增加,MX相的析出量明显增加,而M_(23)C_6碳化物的析出量明显减少,Laves相的析出量小幅增加,Z相的析出量小幅减少;随着V含量的增加,MX相的析出量增加缓慢,M_(23)C_6碳化物的析出量小幅减少,Laves相中不含V元素,对Laves相析出几乎没有影响,Z相的析出量小幅减少;Nb、V含量的变化对M_(23)C_6、MX和Laves相的析出温度影响较小,Z相的开始析出温度随Nb含量的增加而下降,但随V含量的增加而升高。     

高强度管线钢铌、钛元素回溶规律研究

采用电解相分析试验方法,开展高强度管线钢铌钛碳氮化物回溶研究,同时采用简化处理方法进行相关回溶与析出的热力学计算,研究高Nb管线钢中高含量Nb元素和Ti元素回溶规律。结果表明:高Nb管线钢在1 180～1 280℃区间加热,铌、钛实际回溶量都不同程度地低于理论回溶量;温度低于1 250℃时,随加热时间的延长和温度的升高铌回溶效果明显;1 250℃加热2.5 h左右,即可使铌元素回溶90%以上,达到近完全回溶效果,Ti实际回溶较少,仅11%,钛元素形成的钛碳氮化物,具有良好的稳定性。     

2Cr12Ni4Mo3VNbN钢中析出相的热力学计算与试验分析

 利用Thermo-Calc热力学软件计算了2Cr12Ni4Mo3VNbN钢中各个元素在成分范围内均为中值时的平衡相图,同时计算了2Cr12Ni4Mo3VNbN钢中碳、铬、钼、铌、氮元素含量变化时的平衡相图,以此分析钢中主要平衡析出相和合金元素含量对析出相析出行为的影响。为验证热力学计算的可靠性,采用XRD、SEM及TEM等分析方法对热处理后的2Cr12Ni4Mo3VNbN钢中析出相类型进行了试验验证。结果表明,钢中的平衡析出相为MX相、M₂₃C₆、M₆C、Z相和Laves相。在热力学平衡条件下,MX相在850 ℃转化为Z相,M₆C在787 ℃转化为Laves相。但是在实际热处理过程,由于保温时间较短且冷却速度较快,上述转化过程不会发生,所以钢中主要析出相为MX相、M₂₃C₆和M₆C。平衡析出相种类与相分析的试验结果基本一致。MX相存在大尺寸的一次MX相和细小弥散的MX相,MX相主要受铌、氮元素影响,其析出量随氮含量升高而升高,析出温度随铌含量升高而升高;M₂₃C₆相的析出温度随碳含量增加而升高,析出量也随之升高;M₆C的析出温度随铬含量增加而降低,随钼含量增加而升高;在成分范围内,元素控制原则为增加碳含量以增加M₂₃C₆的析出强化作用,减少铬含量以避免热加工时进入δ-Fe相区,减少钼含量以降低Laves相析出倾向,减少铌含量以降低一次MX相的析出温度,氮含量需要采取中间量以减少一次MX相析出,增加低温阶段细小弥散的MX相析出。     

高牌号无取向硅钢平衡析出相热力学计算与分析

以高牌号无取向硅钢典型成分为对象,通过热力学模拟计算,研究Mn,Al元素变化对平衡析出相的影响规律。结果表明:高牌号无取向硅钢的主要平衡析出相为AlN,FCC#2,MnS,M3P,M7C3,M23C6和渗碳体,FCC#2相是一种Ti(C,N)化物,M7C3和M23C6是Mn含量较高的一种化合物。Mn含量增加,MnS固溶析出转变温度大幅升高,当Mn含量较多时,随温度降低M7C3相会先转变成M5C2相,再转变成M23C6相。Al含量增加,Ti(C,N)化物的转变温度降低;AlN固溶析出转变温度升高。Al对MnS,M3P、M7C3和M23C6相的影响较小。     

Ni基粉末冶金高温合金平衡析出相的热力学研究

为了对Ni基高温合金进行优化设计,采用热力学计算软件Jmatpro与相应的Ni基高温合金数据库,对3代粉末高温合金René95、René88DT和René104合金的平衡相析出行为进行了热力学计算与比较研究。结果表明:3种合金的平衡相种类基本相同,主要平衡相为γ、γ’、碳化物M23C6和MC以及硼化物M3B2,但析出量、析出温度及范围存在差别。René104合金有较高的γ’相析出温度和较多的γ’相析出量,而René88DT合金的γ’相析出温度最低,γ’相析出量最少;Ta的添加使Nb元素在γ’相中的含量随温度降低先增加后减少的变化规律变为随温度降低而一直减少;另外,对于碳化物而言,René95和René88DT合金中的碳化物析出规律基本一致,只是析出量和析出温度区间不同,而René104合金与它们存在一定差别。     

A105连铸坯表面横裂纹形成原因分析

应用配有能谱仪的场发射扫描电镜分析了A105钢中裂纹处及基体内残余元素Cu、As和Sn以及P含量.应用Thermo-Calc热力学计算软件计算了A105钢的主要析出相以及钢液中P含量随固相质量分数变化关系.应用Gleeble 1500热模拟试验机对A105钢的高温热塑性进行了研究.发现P偏析是该钢产生横裂的主要原因,残余元素Cu、As和Sn在晶界的偏聚加剧了裂纹的形成,矫直温度偏低加速了裂纹的扩展,而裂纹的形成可能与AlN的析出无关,因为析出的AlN很少.      

ZG1Cr10MoWVNbN钢中碳化物的计算和分析

利用Thermo-Calc热力学软件,对ZG1Cr10MoWVNbN耐热钢在400～1600℃间存在的平衡相进行计算,并通过电化学萃取的方法制取钢中的碳化物粉末,进行XRD分析和形貌观察。结果表明：ZG1Cr10MoWVNbN耐热钢在400～1600℃间的主要平衡析出相为MX、M23C6和Laves相,它们所对应的开始...     

Microstructure Evolution and Mechanical Properties of HR3C Steel during Long-term Aging at High Temperature

Microstructure evolution and the changes in mechanical properties of HR3 Csteel during long-term aging at650,700 and 750℃ were investigated.The precipitated phases of the aging steel included M23C6 carbides,Z-phase and a trace amount of Nb(C,N).The M23C6 carbides were distributed mainly at the grain boundary,while Z-phase was mainly inside the grains.Amounts of both M23C6 carbides and Z-phase during the aging process increased with increasing aging period and temperature.Coarsening of M23C6 carbides was influenced significantly by aging time and temperature,while the size of the Z-phase was relatively less affected by the aging time and temperature,which had a steady strengthening effect.Coarsening of the M23C6 carbides was the main reason for the decline in high temperature yield strength during long-term aging at 750℃.The M23C6 carbides were linked into a continuous chain along the grain boundary which accounted for the decrease of toughness during aging.     

超高强韧油井管合金设计与高强韧机制

 为了揭示1 000 MPa级低碳加铌钒钛微合金钢的高强韧机制,研究了S1(w(C)=0.09%)与S2(w(C)=0.17%)两种合金成分的油井管钢成分-工艺-组织-性能关系。试验表明,两种成分试验钢经水淬后的组织分别为板条贝氏体加少量马氏体和马氏体加少量贝氏体的复相组织。两种成分钢经过450~600 ℃、30 min的中温回火后,组织中均出现碳化物析出,且S1试验钢回火后的屈服强度基本不变,抗拉强度下降了约70 MPa,S2试验钢回火后的屈服强度与抗拉强度迅速升高170 MPa左右。溶度积公式的计算结果表明,两种钢的水淬组织中铌、钛元素析出彻底且析出物的体积分数都很小,因此回火铁素体基体中的VC析出强化对S1试验钢回火后屈服强度保持不变以及S2试验钢回火后屈服、抗拉强度提高起到重要作用。     

Simulation of effect of Nb and V on precipitated phases in 1Cr16Co5Ni2Mo1WVNbN steel

Thermo- Calc software was used to simulate the equilibrium precipitates in the 1Cr16Co5Ni2Mo1WVNbN steel at 650??, and the effect of Nb and V contents on precipitated phases in the steel was investigated. The calculation results show that the main equilibrium precipitates in steel are Laves phase, M23C6, MX and Z phase. With the increase of Nb content, the precipitation of MX phase increases significantly, while the amount of M23C6 carbids decreases, Laves phase increases slightly, the precipitation of Z phase decreases slightly. With the increase of V content, the precipitation of MX phase increases slowly, the amount of M23C6 carbides reduces slightly. There is no V element contained in Laves phase, and the increase of V content has little effect on the precipitation of Laves phase, precipitation of Z phase decreases slightly. The Nb and V contents have little effect on the precipitation temperature of M23C6, MX and Laves phase, and the starting precipitation temperature of Z phase decreases with the increase of Nb content, but increases with the increase of V content.     

The Investigation for Development on Precipitation Phases in 25Co15Ni11Cr2MoE Steel during Tempering

The evolution law of precipitated alloy carbides and reverted austenite in a high Co-Ni secondary hardening ultra-high strength 25Co15Ni11Cr2MoE steel tempered at 300??~ 660?? after quenched has been studied by means of transmission electron microscopy (TEM) and X ray diffraction (XRD) in this paper. The results show that the precipitate order of alloy carbides with the increasing of tempering temperature from 300?? to 600?? in experimental steel is: dispersed ??-carbides?? lamellar alloy cementites?? dispersed M2C carbides?? coarse M23C6 carbides. When the experimental steel tempering at 495??, fine M2C carbides precipitated on the lath martensite matrix. Meanwhile, coarse lamellar alloy cementites that precipitated during the early tempering stage has all dissolved, and reverted austenite precipitated at the boundaries of lath martensite and grows up into thin-film sharp along the lath boundaries. When the tempering temperature rose to 530??, the content of reverted austenite continues to increase, but the morphology of reverted austenite changed from thin-film to strip or block. When the tempering temperature rose to 530??, the content of reverted austenite in the steel reaches maximum value.     

Modeling of γ→α Transformation Temperature Ar3 for High-Nb Pipeline Steel During Cooling Process

 According to the research on the deformation resistance and the ferrite transformation behavior of X80 pipeline steel by using Gleeble-3500 thermal simulator, a mathematical model of the α-phase start transformation temperature for high-Nb pipeline steel was established, based on the transformation kinetics and thermodynamics. The influence of deformation and cooling rate as well as Nb content on the α-phase starting temperature was thoroughly investigated. The results given by the model were in good agreement with the experimental results, which showed that the model could predict the α-phase starting temperature for high-Nb pipeline steel during cooling process.     

Characterization of Electroslag Remelted Super Hard High Speed Tool Steel Containing Niobium

In this work, thermodynamical equilibria have been calculated for super hard high speed tool steel (HSS), AISI M41 composition belonging to the multicomponent system Fe–C–Cr–W–Mo–V–Co as well as for its three different variant containing niobium. Some temperature‐concentration diagram for both class of alloys are presented and calculated quantities (melting and transformations, amount and composition of phases) are compared with experimental data. Effect of niobium and high cooling rate during electroslag remelting on the precipitated carbides were discussed. In this work, the effect of niobium on morphology of carbides secondary hardening temperature and wear rate of investigated HSSs were studied. This work aims to study the effect of niobium as alloying element on precipitated carbides type and shape, in addition to study the effect of precipitated carbides after full heat treatment on secondary hardening and wear resistance for investigated steels.     

700℃以上超超临界电站锅炉过热器管材用典型镍基合金的平衡析出相规律

利用热力学计算软件Thermo-Calc及镍基合金数据库,计算了三种700℃以上超超临界电站用过热器管道材料Inconel740、Inconel617和GH2984合金的热力学平衡相图,并对比了三种材料主要析出相的析出行为.计算结果表明:三种合金主要的析出相包括γ、γ'、碳化物、σ、η、δ、μ及α-Cr等,凝固过程中Mo、Nb和Ti元素偏析严重,会降低合金的初熔点,因此后期均匀化退火处理十分重要.另一方面,750℃时Inconel740合金γ'相析出量大于另外两种合金,并且Al和Ti含量对γ'相和η相析出行为有较大影响.碳化物的计算表明,Inconel617合金一次碳化物与另两种合金不同,并且其二次碳化物的析出温度范围最大.GH2984合金中Fe含量较大时会导致σ相出现,对合金的性能产生不利影响.