Effect of Heat Treatment on Reversed Austenite in Cr15 Super Martensitic Stainless Steel

 The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempered martensite and diffused reversed austenite after quenching at 1050 ℃ and tempering from 550 to 750 ℃. The volume fraction and size of reversed austenite increase with increasing tempering temperature and both of them reach the maximum value at 700 ℃. The volume fraction and size of reversed austenite decrease when the temperature is above 700 ℃. The transmission electron microscope (TEM) results indicate that the orientation relationship between tempered martensite and reversed austenite belongs to Kurdjmov-Sach (K-S) relationship.     

马氏体不锈钢的高温性能与铸坯表面质量的关系

利用DIL402C热膨胀分析仪、STA449C同步热分析仪和Gleeble-1500D热模拟试验机研究了2Cr13不锈钢的线性膨胀系数、主要相变温度以及高温力学性能等高温特性,分析了2Cr13不锈钢高温性能对铸坯表面质量的影响和铸坯表面凹陷及微裂纹产生的机理,为完善攀钢集团长城特殊钢分公司2Cr13小方坯连铸工艺提供了理论依据.     

Formation of Reversed Austenite in High Temperature Tempering Process and its Effect on Mechanical Properties of Cr15 Super Martensitic Stainless Steel Alloyed with Copper

Formation mechanism of the reversed austenite of Cr15 super martensitic stainless steel (SMSS) alloyed with copper after high temperature tempering was investigated by means of thermo‐calc software, transmission electron microscope (TEM), and X‐ray diffraction (XRD). The mechanical properties of the SMSS were also tested. The experimental results show that the reversed austenite with low dislocation density is formed at high temperature tempering processing. The transformation of the martensite to reversed austenite is a diffused phase transformation, and the growth of the reversed austenite is closely related to the diffusion process of Ni. The bulk reversed austenite with large amount of stacking faults is formed with the increase of the tempering temperature. The volume fraction of reversed austenite increases at first and then decreases with increasing tempering temperature, and the maximum amount of the reversed austenite is obtained at 650°C. The reversed austenite is unstable at the tempering temperature above 650°C and the martensitic phase transformation will occur at the following cooling process. The mechanical properties of Cr15 super martensitic stainless steel are significantly influenced by the volume fraction of reversed austenite.     

1Cr13不锈钢的土壤腐蚀行为

通过在酸性、中性及碱性土壤中埋设试件的方法,研究了１Ｃｒ１３不锈钢分别经过１年、３年、５年这三种试验周期后的腐蚀行为为特征。结果表明,１ｃｒ１３不锈钢在酸性及中性土壤中腐蚀轻微,在高盐碱必训腐蚀严重,而且以点蚀为主,土壤中Ｃｌ＾－及ＳＯ４＾２－是影响１Ｃｒ１３不锈钢腐蚀行为的最主要因素,随土壤中Ｃｌ＾－及ＳＯ４＾２－增多,１Ｃｒ１３不锈钢的腐蚀失重近似线性增大。     

Cr Release from Stainless Steels

Cr release from stainless steels in different simulant fluids according to different test conditions is carried out with emphasis on ferritic stainless steels. Effects of Cr content and surface roughness on Cr release are discussed specially with a relation to corrosion resistant and passive film formation. Some primary results are attained： （1） higher Cr content means better corrosion resistance including higher potential and lower corrosion rate and less amount of Cr release from base metal; （2） decreasing surface roughness is in favor of the formation of passive film which can re- train Cr release from base metal effectively; （3） Cr content and surface roughness have synthetical effects on Cr release with a narrow innoxious field referring to surface roughness with decreasing Cr content in stainless steels.     

2Cr13马氏体不锈钢铸坯表面纵裂控制

根据马氏体不锈钢在连铸浇注过程中的凝固收缩特性,分析连铸浇注过程中易引发表面纵裂的原因,提出应对措施,从而有效避免板坯表面纵裂的产生。     

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.     

中国商用飞机高强度不锈钢的现状及发展趋势

 从国内高强度不锈钢发展及分类的角度介绍了各类高强度不锈钢的主要牌号、强度级别、主要优缺点以及应用领域;从商用飞机典型件选材的角度介绍了几种高强度不锈钢的实际应用;展望了国内高强度不锈钢的发展,指出了限制不锈钢发展的因素和今后的发展方向。     

Corrosion Resistance and Semiconducting Properties of Passive Films Formed on 00Cr13Ni5Mo2 Supermartensitic Stainless Steel in Cl- Environment

The semiconducting properties of passive films grown on 00Crl3Ni5Mo2 supermartensitic stainless steel were investigated in comparison with conventional 2Cr13 martensitic stainless steel. Cyclic vohammetry and electro- chemical impedance spectroscopy （EIS） were used for the studies. 00Crl3NiSMo2 steel exhibited a good corrosion resistance performance, attributing to its passive capability. The results of Mott-Schottky analysis demonstrated n- type semiconductors for the passive films with doping densities of about 1020- 1021 cm -3, and the thickness of space- charge layers was also calculated. The experimental results confirmed that Mo plays an important role in improving the corrosion resistance of 00Crl3Ni5Mo2 steel due to its impact on the doping density.     

9Cr马氏体耐热钢发展及其蠕变寿命预测

9Cr马氏体耐热钢是目前热电厂关键设备制造的主选钢种,其最大的特点是600℃左右高温服役条件下良好的持久强度,较好的抗腐蚀性能。本文主要阐述了9Cr马氏体耐热钢的发展及其研究的最新进展,从材料的组织结构、蠕变特性和蠕变寿命预测等多方面叙述了有关9Cr马氏体耐热钢的研究动态。     

Effect of Heat Treatment on Microstructure and Property of Cr13 Super Martensitic Stainless Steel

 The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 754% to 2249%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813-1070 MPa, 101%-212% and 2133-3237, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1050 ℃ followed by tempering at 650 ℃.     

Corrosion Resistance on High Strength Bainitic Steel and 09CuPCrNi After Wet-Dry Cyclic Conditions

The accelerated wet-dry cyclic corrosion tests have been carried out of a high strength bainitic steel and 09CuPCrNi. The results indicated that the corrosion resistance of 09CuPCrNi was better than that of the bainitic steel based on the mass loss measurements. The morphology and composition of the rusting products have been investigated in order to realize the mechanism of rust formation on the two steels. The rust scale on both steels was composed of a dense inner layer and a loose outer layer. The inner layer grew thicker and denser as the test proceeding. Both of inner and outer layers were mainly composed of magnetite (Fe3O4) and maghemite (γ-Fe2O3) with a small amount of lepidocrocite (γ-FeOOH) and akaganeite (β-FeOOH). The rust phase of γ-Fe2O3 was detected in a higher amount of the inner layer, resulting in a much denser inner layer. The inner rust layer of 09CuPCrNi being denser and thicker than that of the high strength bainitic steel was attributed to the alloying elements such as copper, chromium and phosphorus enriched in it. The protective inner rust layer plays an important role in the corrosion resistance of the steel.     

沸腾稀硝酸中Cr6+对高纯不锈钢耐蚀性的影响

 研究了在稀硝酸中添加不同含量的Cr6+对高纯奥氏体不锈钢耐蚀性的影响。结果表明,Cr6+在沸腾硝酸中对不锈钢有明显的加速腐蚀作用,当Cr6+超过一定含量时,还伴随着晶间腐蚀。Cr6+浓度与腐蚀速率近似呈线性关系。     

高N马氏体不锈轴承钢的热变形行为

利用Gleeble-3800热模拟试验机在温度为1 040~1 120℃,应变速率为1~20s-1的条件下进行了高N马氏体不锈轴承钢的热压缩变形试验。结合真应力-真应变曲线和热变形组织研究了变形参数对高N马氏体不锈轴承钢的热变形行为和碳氮化物演变规律的影响。结果表明:在该变形条件下,试验钢的真应力-真应变曲线为动态再结晶型。随着应变量的增大,碳化物的平均尺寸呈减小趋势,但数量有所增多。基于热变形方程计算得到的应变量为0.6时的热变形激活能Q为410.7kJ/mol。构建了包含应变量在内的流变应力方程,同时建立了高N马氏体不锈轴承钢的Zener-Hollomon参数本构方程。     

热处理工艺对0Cr15Ni5Cu2Ti马氏体不锈钢组织和性能的影响

本文对不同固溶和时效温度下的0Cr15Ni5Cu2Ti马氏体不锈钢组织及性能进行分析，以此确定该钢的热处理工艺，同时对该钢的强化机理进行分析。     

马氏体不锈钢板坯连铸保护渣研制与应用

 由于钢种特点,连铸马氏体不锈钢板坯容易产生裂纹缺陷,影响生产节奏和修磨效率;同时,由于采用通用型保护渣,也无法针对马氏体不锈钢板坯质量问题做出进一步改进。因此,尝试马氏体不锈钢板坯连铸保护渣的国产化研制和使用,通过保护渣碱度、CaF等的不同范围与保护渣结晶、黏度性能的关系研究,确定采用高碱度、低黏度、高结晶性的保护渣设计原则,并由此得出了适应马氏体不锈钢板坯连铸的保护渣设计方案。实际使用过程中,板坯纵裂率下降幅度达到30%,证明了马氏体不锈钢连铸板坯保护渣设计和研制的合理性和可行性。