超低碳Cr-Ni马氏体不锈钢组织和性能研究

采用SEM和金相相结合的方法，观察了不同热处理工艺下超低碳Cr-Ni马氏体不锈钢0．02C-13Cr-4Ni-1Mo-0．04N的组织和断口形貌；在Gleeble3800热模拟试验机上采用体积膨胀法，分析其相变过程并进行了500℃热拉伸对比试验。按照GB228、GB230要求测试不同热处理制度下材料屈服强度Rp0.2、抗拉强度Rm、延伸率A。试验结果表明，其室温基体金属的显微组织为低碳回火马氏体，Ac1为720℃，Ac3为860℃，Ms为281℃，Mf为157℃；在相同的淬火温度和回火工艺下，采用水淬较空冷更容易实现对力学性能的控制；随着回火温度的升高，合金的强度、硬度越低，塑性、韧性越好。     

氮元素对Cr13超级马氏体不锈钢组织及性能的影响

为了提高超级马氏体不锈钢的性能以满足油气开采的使用要求,在Cr13超级马氏体不锈钢中添加质量分数为0.065％的N元素,并采用金相观察、SEM、拉伸试验、电化学测试等方法,研究N元素对Cr13超级马氏体不锈钢组织、力学性能及耐蚀性能的影响.研究发现,N元素能细化原奥氏体晶粒、对组织中的回火马氏体有一定的\"短化\"作用,并...     

13Cr超级马氏体不锈钢热变形特性

为了探讨生产13Cr超级马氏体不锈钢合适的热变形温度,在Gleeble1500热模拟试验机上对13Cr超级马氏体不锈钢进行了应变速率为2.5 s-1、不同变形温度下的高温热塑性试验及热压缩试验,对变形后的试样进行了金相组织观察,并对回火后组织中逆变奥氏体含量进行了测定。结果表明,13Cr超级马氏体不锈钢回火前的马氏体板条粗大,回火后的马氏体发生显著的细化;根据高温热塑性曲线、热变形过程再结晶组织及回火后逆变奥氏体含量,确定13Cr超级马氏体不锈钢适宜的变形温度为1 050~1 150 ℃。     

热处理工艺对高氮超级马氏体不锈钢组织性能的影响

超级马氏体不锈钢因其良好的耐腐蚀性能和力学性能,在航空航天、石油、化工等领域具有广泛的应用前景。淬火-配分（QP）工艺是提升中高碳马氏体不锈钢力学性能的有效手段,由于超级马氏体不锈钢碳含量过低,配分效果不明显,所以对其进行氮合金化处理,利用氮配分代替传统的碳配分来稳定奥氏体。但配分工艺一般持续时间较短,无法实现置换原子的扩散,为了进一步增加奥氏体的稳定性,将双相区淬火（L）和QP工艺相结合,称为QLP工艺。以高氮超级马氏体不锈钢为研究对象,采用万能拉伸试验机、X射线衍射仪、扫描电子显微镜及透射电子显微镜设备,对不同热处理工艺试样微观组织及力学性能进行分析。结果表明,2组试验钢均表现出优异的综合力学性能,QLP样品的屈服强度和抗拉强度分别为713 MPa和1 344 MPa,伸长率为31.03%,相较于QP样品屈服强度提高了166 MPa,而塑性没有明显降低。试验钢经QP和QLP工艺处理后,显微组织均由马氏体和奥氏体双相组成,奥氏体分为块状和薄膜状2种形态。QP试验钢奥氏体体积分数为42.6%,而增加了双相区淬火工艺后,试验钢奥氏体体积分数降低为21.9%,块状奥氏体尺寸明显减小且存在更多的薄膜状奥氏体。分析认为,这是双相区淬火过程中二次马氏体生成和奥氏体稳定性增加的综合影响结果。     

超级不锈钢的种类

超级不锈钢一般分为五类，即超级马氏体不锈钢、超级铁素体不锈钢、超级奥氏体不锈钢、超级双项不锈钢、马氏体时效不锈钢。     

热处理工艺对新型刀具用马氏体不锈钢6Cr15Mo组织和性能的影响

研究了6Cr15Mo钢(%:0.59C、14.96Cr、0.52Mo、0.22V、0.004 6N)1 000～1100℃淬火的组织和硬度,以及1080℃淬火+100～700℃回火时,该钢的组织、硬度和冲击韧性。结果表明,1080℃淬火6Cr15Mo钢硬度值最高(平均HRC值61.6),在500℃回火出现二次硬化峰,冲击韧性较低(12 J/cm~2),采用1 080℃淬火+150～250℃回火,可获得最佳强韧性配合(平均HRC值55,冲击值17 J/cm~2)。     

热处理工艺对Cr17含Ni马氏体不锈钢组织及性能的影响

通过对Cr17含Ni马氏体不锈钢热处理工艺试验,研究了不同的淬火和回火温度对Cr17含Ni马氏体不锈钢（低、高倍）组织和力学性能的影响。试验结果表明：经过淬火＋高温回火处理后,材料晶粒明显细化,材料的综合力学性能得到最大提高。同时,在中温回火时,材料的强度和硬度有所提高,塑性和韧性略有降低,出现明显的中温回火脆性倾向。Cr17含Ni马氏体不锈钢的使用状态组织为索氏体,具有良好的耐蚀性能,又具有较高的强度和韧性配合。     

04Cr13Ni5Mo超级马氏体不锈钢焊接性能研究

模拟了04Cr13Ni5Mo超级马氏体不锈钢不同焊接热循环条件下热影响区组织,进行了焊条电弧焊接及焊后热处理试验,分析了焊接热模拟试样及焊条电弧焊接头的微观组织、力学性能.焊接热模拟试验结果表明,模拟热影响区的组织主要为低碳板条马氏体,其硬度较母材有较大提高,冲击韧性有所下降;模拟单道焊或多道焊时,不同的冷却速度及层间热处理对模拟热影响区的硬度及冲击韧性影响不大,600℃焊后回火热处理可以明显软化模拟热影响区组织,并让其冲击韧性恢复到较高水平.焊条电弧焊接结果表明,采用04Cr13Ni5MoRe型焊条及配套的焊后热处理工艺,可以获得良好综合力学性能的焊接接头.     

Studies on Nb Microalloying of 13Cr Super Martensitic Stainless Steel

The effect of Nb microalloying on microstructure, mechanical properties, and pitting corrosion properties of quenched and tempered 13?pct Cr-5?pct Ni-0.02?pct C martensitic stainless steels with different Mo and N contents was investigated. The microstructure, density, and dispersion of high-angle boundaries, nanoscale precipitates, and amount of retained austenite were characterized by using electron backscattered diffraction, transmission electron microscopy, and X-ray diffraction to correlate with properties. The results show that the combined effects of lowering nitrogen content in 13?pct Cr-5?pct Ni-1~2?pct Mo-0.02?pct C steels to 0.01?wt pct, and adding 0.1?pct Nb are to decrease the amount of Cr-rich precipitates, as Nb preferentially combines with residual carbon and nitrogen to form carbonitrides, suppressing the formation of Cr₂N and Cr₂₃C₆. Austenite grain refinement can be achieved by Nb microalloying through proper heat treatment. If the nitrogen content is kept high, then Cr-rich precipitates would occur irrespective of microalloying addition. The NbN would also occur at high temperature, which will act as substrate for nucleation of coarse precipitates during subsequent tempering, impairing the toughness of the steel. It was shown that the addition of Nb to low interstitial super martensitic stainless steel retards the formation of reversed austenite and results in the formation of nanoscale precipitates (5 to 15?nm), which contribute to a significant increase in strength. More importantly, the pitting corrosion resistance was found to increase with Nb addition. This is attributed to suppression of Cr-rich precipitates, which can cause local depletion of Cr in the matrix and the initiation of pitting corrosion.     

ZG06Cr13Ni4Mo马氏体不锈铸钢组织对性能的影响

ZG06Cr13Ni4Mo马氏体不锈钢水轮机铸件的组织和性能试验分析的结果表明，若出现类似魏氏体组织的δ-铁素体时，铸钢件的冲击韧性急剧下降。经正火处理可消除该铸钢中的δ-铁素体相。     

合金元素对2Cr13马氏体不锈钢组织及性能的影响

Ni,Mo,V均是影响13Cr型马氏体不锈钢性能的主要元素.研究了在普通2Cr13基础上添加不同含量的Ni,Mo以及微量V对其力学性能、耐腐蚀性能的影响.研究表明:单独添加Ni或Mo元素均未能明显改善2Cr13型马氏体不锈钢的综合力学性能,但同时添加适量的Ni,Mo等合金元素能明显提高材料的力学及耐CO2腐蚀性能.     

氮对0Cr13Ni4Mo马氏体不锈钢机械性能的影响

研究结果表明,含0．018％N的低氮对0Cr13Ni4Mo马氏体不锈钢未出现中温回火脆性,含0．054％N的高氮钢有中温回火脆性出现,经600℃高温回火后可获得高的强韧性配合和极高的－60℃低温冲击韧性。     

马氏体不锈钢2Cr13工艺探讨

分析研究扁平材厂生产的马氏体不锈2Cr13(餐具用钢)出现的技术、质量问题:表面抛不光,表面质量差,板形不好,通过理论和实战跟踪分析,改进生产工艺:改进加热工艺,采用新型轧辊轧制,改进热处理工艺.基本解决了马氏体不锈钢2Cr13的表面质量问题(表面抛不光问题).     

30Cr13马氏体不锈钢电阻焊工艺研究

通过金相、显微硬度以及电子探针等技术,研究了30Cr13马氏体不锈钢电阻焊不同材质和焊接电流下对组织和性能的影响。结果表明,焊接前的打磨工作会影响焊接接头弯曲性能;30Cr13与30Cr13焊接时熔深明显大于30Cr13与SUS304焊接接头熔深;而30Cr13与SUS304焊接接头熔核直径随焊接电流增大而增大,当焊接电流为11 500 A时焊接接头硬度值最低,弯曲性能最好,满足生产工艺要求。     

Passivation Behaviors of Super Martensitic Stainless Steel in Weak Acidic and Weak Alkaline NaCl Solutions

The passivation behaviors of super martensitic stainless steels(SMSS)were studied by polarization curves at passive potential of-0.1Vand in various NaCl solutions,electrochemical impedance spectroscopy(EIS)and Xray photoelectron spectroscopy(XPS)analysis.Electrochemical test results showed that,in alkaline solutions,passivation region width was wider,passivation current was smaller,and polarization resistance was greater;thus,the passive film of SMSS in alkaline solutions had better passivation behaviors than that in acidic solutions.The polarization curve and EIS of samples SMSS1 and SMSS2were also used to study which sample had better passivation behaviors.All results demonstrated that passive film structure of SMSS1 sample was more stable,and capacity of passive film was enhanced.The impact of alloying elements on the passive film(SMSS)passivation capability was also discussed by XPS depth profiling,and XPS depth profiling showed that the composition of the passive film was mainly composed of Fe-oxide and Cr-oxide.So the passive film structures were mixed layers of Fe-oxide and Cr-oxide.Fe oxidation product and Cr oxidation product would help to improve the protective property of passive film,which could promote the formation of a passive film structure more stably and densely.     

氮合金化对马氏体不锈钢00Cr13Ni4Mo回火性能的影响

测定了控氮00Cr13Ni4Mo(S13-4N)与低氮00Cr13Ni6Mo(S13-6)的性能,对比分析了氮元素对00Cr13Ni4Mo的强度、韧性、耐蚀性的影响。力学性能测试结果表明,回火温度≤550℃时,控氮的S13-4N比低氮的S13-6的强度更高,韧性更低;回火温度≥550℃时,规律逐渐变得相反;S13-4N在450℃左右出现回火脆性现象。电化学测试结果表明,S13-6的耐点蚀性能优于S13-4N。XRD和EBSD结果表明,两种钢在550℃以上温度回火时出现逆变奥氏体,600℃附近含量达到最大值,此时的韧性最佳,S13-6中的逆变奥氏体总量多于S13-4N,但形态不同。分析认为:氮比镍稳定奥氏体的能力强,而镍形成逆变奥氏体的能力则更强,逆变奥氏体的含量和稳定性对韧性的影响很大;S13-4N的450℃回火脆性主要是由于碳化物和氮化物的析出引起的。     

Phase-Dependent Tensile Properties of 9Cr-1Mo(V, Nb) Ferritic/Martensitic Steel

Phase-dependent tensile properties of 9Cr-1Mo(V, Nb) ferritic/martensitic steel were evaluated in the temperature range 300 K to 1073 K (27 °C to 800 °C) to quantify differences in the tensile behavior of different phases of this material. The results showed considerable difference in the tensile properties such as yield strength, ultimate tensile strength, and elongation of the three phases of this material—tempered martensite, metastable austenite, and martensite—which can exist at a common temperature. This has been discussed on the basis of structural hysteresis in this material when subjected to thermal cycles causing excursions across various phase fields.     

Effect of Deep Cryogenic Treatment on Formation of Reversed Austenite in Super Martensitic Stainless Steel

The effect of deep cryogenic treatment on the formation of reversed austenite(RA)in super martensitic stainless steel was investigated.RA was found to form in steels without(A)and with(B)deep cryogenic treatment.The volume fraction of RA initially increased and then decreased with increasing tempering temperature over 550-750 ℃for the two steels,which were quenched at 1 050 ℃.In addition,for both with and without deep cryogenic treatment,the RA content reached a maximum value at 650 ℃ although the RA content in steel B was greater than that in steel A over the entire range of tempering temperatures.Furthermore,the hardness(HRC)of steel B was greater than that of steel A at tempering temperatures of 550-750 ℃.From these results,the basic mechanism for the formation of RA in steels A and B was determined to be Ni diffusion.However,there were more Ni-enriched points,a lower degree of enrichment,and a shorter diffusion path in steel B.It needed to be noted that the shapes of the RA consisted of blocks and stripes in both steels.These shapes resulted because the RA redissolved and transformed to martensite along the martensitic lath boundaries when the tempering temperature was 650-750 ℃,and a portion of RA in the martensitic lath divided the originally wider martensitic laths into a number of thinner ones.Interestingly,the RA redissolved more rapidly in steel B and consequently resulted in a stronger refining effect.