Relationship Between Microstructure and Corrosion Behavior of Cr12Ni3Co12Mo4W Ultra-High-Strength Martensitic Stainless Steel

The effect of tempering temperature on the microstructure and corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength martensitic stainless steel was investigated using transmission electron microscopy, atomic force microscopy, X-ray diffraction, and electrochemical tests. The microstructures of the ultra-high-strength martensitic stainless steel consisted of some retained austenite and lath/plant martensite with the carbides distributed within the matrix and at the grain boundaries. Tempering of the steel for 4 h at various temperatures resulted in various carbide grain sizes and different amounts of the retained austenite. The results showed that larger carbide grains led to diminished corrosion resistance, whereas larger amounts of the retained austenite resulted in improved corrosion resistance. The steels exhibited good corrosion resistance in 0.017 mol/L NaCl solution and exhibited pitting corrosion in 0.17 mol/L Na Cl solution. The martensite and prior austenite crystal boundaries dissolved in solution with pH 1.     

2Cr12Ni4Mo3VNbN新型叶片钢高频淬火后的显微组织与疲劳性能

为提高2Cr12Ni4Mo3VNbN马氏体不锈钢叶片的疲劳性能,对调质处理后的叶片刃口区进行了高频淬火处理,研究了高频淬火前后2Cr12Ni4Mo3VNbN钢的显微组织、残余应力分布和疲劳性能。结果表明:2Cr12Ni4Mo3VNbN钢高频淬火后显微组织中的原奥氏体晶粒和马氏体板条束都得到细化,没有明显的析出物,而未高频淬火的马氏体有较多窄条状M3C析出。2Cr12Ni4Mo3VNbN叶片高频淬火区表层层深0.1 mm以内主要为压应力,应力值约在-450 MPa^-20 MPa之间,且随层深增加而减小。高频淬火态2Cr12Ni4Mo3VNbN钢的疲劳裂纹扩展门槛值为6.75 MPa·m^1/2,高于未高频淬火态下的4.73 MPa·m^1/2,并且高频淬火态2Cr12Ni4Mo3VNbN钢中的疲劳裂纹扩展速率低于未高频淬火态。这表明,高频淬火处理提高了2Cr12Ni4Mo3VNbN马氏体不锈钢的疲劳裂纹扩展抗力和疲劳裂纹扩展寿命。     

0Cr16Ni5Mo1马氏体不锈钢的连续冷却相变动力学

采用显微组织表征和硬度测试研究了0Cr16Ni5Mo1马氏体不锈钢连续冷却转变动力学和显微组织演化规律。结果表明:0Cr16Ni5Mo1马氏体不锈钢在1100 ℃×60 min奥氏体化条件下,以0.5~100 ℃/s的速度冷却时仅发生马氏体转变,马氏体相变的开始温度(Ms)约为212 ℃,结束温度(Mf)约为25.3 ℃,组织均为板条马氏体,硬度约为371 HV。冷却速率的变化对相变温度、室温组织和硬度无显著影响。采用K-M方程描述马氏体相变过程,其相变动力学参数α约为0.0317。     

氮对马氏体不锈钢00Cr13Ni4Mo组织和性能的影响

采用热膨胀仪、光学显微镜以及CM12型透射电子显微镜研究了添加0.04%N(质量分数)对00Cr13Ni4Mo马氏体不锈钢相变以及正火和回火后不锈钢组织变化的影响;通过拉伸、冲击实验和阳极极化曲线测定研究了N对正火和回火后马氏体不锈钢力学性能以及点蚀点位的影响。结果表明:1050℃正火后,N全部固溶于马氏体基体中,有效提高了实验钢的强度,同时降低了韧性;550℃以上回火后,在马氏体板条内部以及板条之间形成逆变奥氏体,有效提高了马氏体不锈钢的塑性和韧性;N抑制逆变奥氏体的形成,从而抑制了不锈钢在回火过程中的软化;同时,回火过程中,Cr2N在马氏体板条界面及内部大量析出,造成不锈钢韧性和点蚀点位下降。采用传统的正火+Ac1温度以上回火热处理工艺不利于含N马氏体不锈钢获得良好综合性能。     

00Cr22Ni13Mn5Mo2N奥氏体不锈钢的精轧工艺

为了研究00Cr22Ni13Mn5Mo2N奥氏体不锈钢的精轧工艺,使用Gleeble-3800热模拟试验机模拟00Cr22Ni13Mn5Mo2N奥氏体不锈钢在变形温度为800、850、900、950 ℃,变形量为40%、50%、60%,应变速率为50 s^-1条件下的热压缩变形行为,并对其进行1080、1120、1160 ℃的固溶热处理,观察固溶热处理前后的组织形貌。结果表明:在800~950 ℃热压缩温度下,随变形量增大,再结晶越完全,再结晶平均晶粒尺寸越细小;经固溶处理1 h后,静态再结晶就越充分。在40%~60%变形量下,随热压缩温度升高,再结晶越完全,再结晶平均晶粒尺寸越大。热压缩变形试验钢随固溶处理温度升高,再结晶平均晶粒尺寸越大。00Cr22Ni13Mn5Mo2N奥氏体不锈钢的精轧最佳轧制温度为800 ℃,压缩变形量为60%,固溶温度为1080 ℃。     

0Cr16Ni5Mo马氏体不锈钢δ-铁素体含量及奥氏体晶粒度的控制

检验中发现0Cr16Ni5Mo钢的δ-铁素体含量超出技术协议规定值,为降低δ-铁素体的含量同时控制奥氏体晶粒度以满足材料使用要求,通过理论计算和热力学模拟分析δ-铁素体形成原因,后续采用不同温度的淬火和高温扩散对0Cr16Ni5Mo钢组织和δ-铁素体含量变化进行对比研究,另外采用两种循环热处理方式对奥氏体晶粒度进行控制。结果表明,随着淬火温度的提高,0Cr16Ni5Mo钢的奥氏体晶粒度不断增大,而对δ-铁素体含量的减少作用相对有限。高温扩散能使δ-铁素体明显减少,但当扩散温度大于奥氏体向δ-铁素体转变温度时,会相对延缓铁素体的溶解。进行1130 ℃的高温扩散后,可以采用850 ℃和830 ℃的变温循环相变热处理,消除马氏体组织遗传,均匀细化奥氏体晶粒。     

4Cr14Ni14W2Mo钢氮化层剥落的研究

Unthank等人曾指出,含Cr高的奥氏体不锈钢在600～800℃氮化时,将沿晶界形成大量的CrN,并可能导致沿晶开裂,造成氮化层剥落.Kindlimann和Ansell认为,氮化表面上Fe或Ni-Fe的氮化物增到一定厚度时将产生“白亮层”,冷却时可能剥落。高濑孝夫在讨论氮化温度对18-8钢氮化层脆性影响时指出,低温氮化易出现氮化层剥落。本工作通过氮化前对试样作适当的预先热处理找到了解决氮化层剥落的方法,并探明了氮化层剥落的原因。     

Cr3型压铸模具钢4Cr3Mo2V的CCT和TTT曲线

利用DIL805A淬火变形膨胀仪对新型Cr3型热作模具钢4Cr3Mo2V进行过冷奥氏体连续冷却转变和过冷奥氏体等温转变试验,研究了冷却速度对相变组织和硬度的影响,绘制了Cr3钢的CCT曲线和TTT曲线,并与Cr5型4Cr5Mo2V钢的CCT曲线和TTT曲线进行对比。结果表明,Cr3钢的Ms=320℃,Ac₁=795℃,Ac_cm=895℃。当Cr3钢以不同速度连续冷却时,分别出现了珠光体转变、贝氏体转变和马氏体转变。与Cr5钢相比,Cr3钢的CCT曲线左移,淬透性降低。Cr3钢的TTT曲线呈“双C型”,贝氏体转变区的温度范围在320～410℃,珠光体转变区的温度范围在650～750℃,“鼻尖”温度出现在715℃左右,珠光体转变结束所需时间为17 882 s。     

SPALLING MECHANISM OF NITRIDED LAYER OF AUSTENITIC STEEL 4Cr14Ni14W2Mo

The tendency of spalling of the nitrided layer of the hot rolled austenitic steel4Cr14Ni14W2Mo exhibits close relation to the nitrided surface orientation relative to the rol-led steel rod.It is found that the dislocations in the imperfectly recrystalized steel align asparallel dislocation walls in macroscopic extent,and the thickness of the“white sublayer”inthe nitrided layer is much larger at the surface which is parallel to the dislocation walls.Onsuch surface the spalling of the nitrided layer happens often.     

Solid particle erosion behaviour of 13Cr–4Ni and 21Cr–4Ni–N steels

The 13Cr–4Ni martensitic stainless steel (termed as 13/4 steel and popularly known as CA6NM steel) is currently being used for fabrication of under water parts in hydroelectric projects. There are, however, several maintenance problems associated with the use of this steel. A 21Cr–4Ni–N nitronic steel (termed as 21-4-N steel) has been developed as an alternative with the specific aim of overcoming these problems. A comparative study has been made on the erosion behaviour of as cast 13/4, and as cast and hot rolled 21-4-N steels by means of solid particle impingement using gas jet. It is observed that the hot rolled 21-4-N nitronic steel possesses excellent resistance to erosion followed by as cast 21-4-N and 13/4 steels. The austenitic matrix of the hot rolled 21-4-N steel possesses high hardness coupled with ductility, high tensile toughness and work hardening ability, which result in higher erosion resistance. The erosion damages are in agreement with studies of eroded surfaces on scanning electron microscope (SEM).     

2Cr19Ni9Mo不锈钢的强化

用光学显微镜、扫描电镜、透射电镜对２Ｃｒ１９Ｎｉ９Ｍｏ不锈钢强化机理进行了分析。结果表明，时效强化及形变强化的综合作用可使２Ｃｒ１９Ｎｉ９Ｍｏ不锈钢得到较高的强度。     

氯和氢对新型超高强度Cr12Ni4Mo2Co14钢在酸性环境中电化学腐蚀行为的影响

采用极化曲线、电化学阻抗和Mott-Schottky等电化学试验研究了酸性环境中Cl~-和氢对一种新型超高强度Cr12Ni4Mo2Co14钢电化学腐蚀行为的影响。结果表明:Cl-和氢均对Cr12Ni4Mo2Co14钢的阳极钝化区产生影响,随着Cl~-含量和氢含量的增加,点蚀电位负向移动,钝化区间缩短;Cl-通过占据氧空位促进钝化膜中形成Schottky空位对,而金属离子空位聚集会引起钝化膜的破坏;与未充氢Cr12Ni4Mo2Co14钢相比,充氢Cr12Ni4Mo2Co14钢中的施主和受主密度均有所提高,导致阳离子空位浓度提高,局部阳离子空位的聚集可诱导钝化膜的击穿。     

00Cr22Ni5Mo3N双相不锈钢热加工性能的试验研究

采用热压缩和热拉伸试验方法,对00Cr22Ni5Mo3N双相不锈钢的高温变形抗力、高温塑性以及在高温变形时的奥氏体相的数量进行了研究。试验结果表明,00Cr22Ni5Mo3N双相不锈钢的高温变形抗力和高温塑性较0Cr18Ni10Ti奥氏体不锈钢低,在1100～1250℃变形时,钢中奥氏体相的数量可以控制在适合热加工的范围,使钢具有较好的热加工性能。     

激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层组织与耐磨性

以39Mo-35Ni-26Si(w％)合金粉末为原料，采用激光熔覆技术，在1Cr18Ni9Ti不锈钢基材表面翩得以Mo2Ni3Si金属硅化物为初生相，以Mo2Ni3Si／NiSi共晶相为基体的金属硅化物耐磨复合材料涂层。涂层的常温干滑动磨损试验结果表明，在磨损过程中，Mo2Ni3Si／NiSi共晶相轻微地优先磨损，Mo2Ni3Si金属硅化物微微凸出于磨损表面，起到抗磨的骨干作用。由于Mo2Ni3Si金属硅化物具有很高的硬度和很强的原子间键合力，在磨损过程中难于变形和粘着，激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层具有优异的耐磨性，与1Cr18Ni9Ti标样相比，涂层的耐磨性提高了56倍。     

Korrosion von Stahl vom Typ 03Cr18Ni13Mo2,5 und 02Cr25Ni22Mo2N bei der Harnstoffsynthese

Corrosion of steels type 03Cr18Ni13Mo2.5 and 02Cr25Ni22Mo2N in urea processing environment Long-term corrosion tests with the steel types 03Cr18Ni3Mo2.5 having different chemical compositions and chemical purity, and 02Cr25Ni22Mo2N have been carried out for up to 112517 and 64 699 h, respectively, in the urea manufacture environment. According to the results the first steel is a suitable material of construction for the high pressure parts of urea plant, provided its chromium content is higher than 18%. This quality meets requirements of urea grade steels. The steel 02Cr25Ni22Mo2N is even more corrosion resistant, but its use may be critical because of the high nickel content. A mathematical model has been developed for the weight loss-time-dependence and the results have been extrapolated to up to 1.5 ·10⁵h.     

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用600℃时效微观组织变化和冲击韧性的变化评价了1Cr21Ni5Ti双相不锈钢的稳定性。结果表明：1Cr21Ni5Ti双相不锈钢稳定性对Ti/C极为敏感,低Ti/C（Ti/C=4.08）钢600℃时效快速析出富Cr的M23C6碳化物,降低奥氏体内的Cr和C含量致使时效后冷却过程中奥氏体转变为马氏体,并伴随着冲击韧性的严重恶化;而Ti/C适度的钢明显抑制了M23C6碳化物的析出和随后奥氏体向马氏体转变,长时间时效后冲击韧性高出低Ti/C钢近一倍。     

Thermodynamics of phosphorus grain boundary segregation in 17Cr12Ni austenitic steel

The paper presents results of thermodynamic analysis of phosphorus grain boundary segregation in 17Cr12Ni austenitic steel annealed for 1000 h at 923, 973 and 1073 K. With respect to values of compensation temperature τ_P=930 K and segregation enthalpy ΔH_P⁰=−14.1 kJ/mol the analyzed interfaces were considered to be special grain boundaries.     

喷焊材料对OCr13Ni4Mo钢表面强化的影响

选用自熔合金粉末Ni60和Ni25B,采用氧－乙炔喷焊技术对0Cr13N4M钢的表面进行强化处理,并对喷焊层的组织、结合强度、硬度及耐磨性进行了研究,结果表明：两种粉末的喷焊层均与基体0Cr13Ni4Mo钢有良好的结合强度;喷焊层的硬度、抗磨损性均高于基体。     

Warmverformbarkeit und Korrosionswiderstand von Stählen der Type 1Cr18Ni12Mo2Ti

Hot workability and corrosion resistance of 1Cr18Ni12Mo2Ti type steels Increasing the Mo content to the level required for corrosion resistance has a negative effect on the hot workability of austenitic steels. Addition of 2% Mo requires an increase in the proportion of austenite-forming elements (in particular Ni), while the Cr content must be reduced to the lowest admissible value for corrosion resistance. As has been shown by experimental work in a redox system and in a pulp digester 16–20% Cr can be considered sufficient (corrosion loss 0,01 mm/y). In bleach liquors of the textile industry, however, there is the danger of pitting corrosion. Heat treatment and hot working have a very pronounced bearing on corrosion resistance.     

超细颗粒焊剂约束电弧超窄间隙焊接1Cr18Ni9Ti不锈钢的焊缝成形分析

将超细颗粒焊剂约束电弧超窄间隙焊接用于1Cr18Ni9Ti奥氏体不锈钢,通过改变焊接速度、电弧电压、焊接电流对焊缝成形进行了研究.结果表明,在热输入为1.75 kJ/mm和深宽比为1.34的条件下,也不易形成"梨形"焊道裂纹,并且单道焊接时熔化焊丝在超窄间隙内的填充高度可达11.5 mm.在其它焊接参数确定的情况下,随着电弧电压的增加,1Cr18Ni9Ti奥氏体不锈钢超窄间隙焊缝依次呈"凸焊缝"、"凹焊缝"及"电弧攀升"的成形规律.适合于超细颗粒焊剂约束电弧超窄间隙焊接1Cr18Ni9Ti奥氏体不锈钢的电弧电压与焊接电流匹配范围分别约为26~32 V和200~320 A.