回火温度对0．2C－14Co－12Ni－3Cr－1Mo钢组织与性能的影响

在４３０℃回火，板条间存在的渗碳体使０．２Ｃ－１４Ｃｏ－１２Ｎｉ－３Ｃｒ－１Ｍｏ钢的冲击韧性和断裂韧性出现最低值。４５０℃回火导致了硬化峰（σ＿ｂ≈２１０５ＭＰａ），主要是细小共格析出的碳化物所致。最佳的性能配合为拉森－米勒参数（ＬＭＰ）等于２８０００～２８３００时的回火温度。对应的回火温度为４８２℃。     

超高强度钢15Cr2Ni10MoCo14回火组织的研究

利用透射电子显微镜（ＴＥＭ）系统研究了１５Ｃｒ２Ｎｉ１０ＭｏＣｏ１４的超高强度钢回火后的微观组织结构。从低温到高温回火，钢的回火马氏体组织中顺次析出Ｆｅ３Ｃ，Ｍ２Ｃ，Ｍ２３Ｃ６和Ｍ６Ｃ，并在６５０℃过时效回火时发现一种在钢的回火组织中未见报道过的正交结构相，点阵常数为ａ＝０．４４８ｎｍ，ｂ＝１．４０ｎｍ，ｃ＝１．２１ｎｍ。     

超低碳Cr26－Ni28－Mo5－Cu3－Nb0．35铸造不锈钢的组织和耐蚀性能

用金相、透射电子显微镜、电子探针与扫描电镜分析研究得出，超低碳Ｃｒ２６－Ｎｉ２８－Ｍｏ５－Ｃｕ３－Ｎｂ０．３５不锈钢铸态组织中含有σ相，经８５０～１１２０℃热处理均可形成σ相，包括（Ｆｅ－Ｃｒ）σ相，（Ｆｅ－Ｍｏ）σ相和（Ｃｒ－Ｎｉ－Ｓｉ）σ相；８５０℃左右有Ｍ６Ｃ型碳化物和ＮｂＣ析出。该钢经１１５０℃２ｈ水冷固溶处理后，具有优良的耐腐蚀性能。     

15Cr2Ni10MoCo14钢奥氏体晶粒长大和高温氧化动力学

１５Ｃｒ２Ｎｉ１０ＭｏＣｏ１４钢的抗氧化性能在低温区（＜１０００℃）具有比高温区（＞１０５０℃）明显优异的特征。在９００～１０００℃和１０５０～１３００℃的不同温度范围内，晶界迁移率分别为ｖ＝６．２６×１０６ｅｘｐ（－１．５６×１０４／Ｔ）和ｖ＝２．０７４×１０６ｅｘｐ（－１．１８×１０４／Ｔ）。     

尿素设备用00Cr17Ni14Mo2不锈中板的试制

经多年试制,太钢生产了数十吨尿素级００Ｃｒ１７Ｎｉ１４Ｍｏ２（３１６Ｌ）钢板材和锻材,用于制造化肥尿素设备,摸索出了一套较为成熟的生产工艺,为尿素级３１６Ｌ钢国产化奠定了基础。１产品技术条件００Ｃｒ１７Ｎｉ１４Ｍｏ２钢标准化学成分见表１。６５％沸腾硝...     

0．03C－4．5Si－14Cr－8Ni双相铸造不锈钢的组织和耐蚀性

本文对所设计的０．０３Ｃ－４．５Ｓｉ－１４Ｃｒ－８Ｎｉ（ＤＬＮＧＧ）双相铸造不锈钢进行了组织和耐蚀性研究。试验结果表明，该钢经１０５０℃１．５ｈ水冷固溶处理后，得到铁素体－奥氏体双相组织，在浓硫酸介质中有良好的耐蚀性能。     

32Mn－7Cr－1Mo－0．3N奥氏体钢的动态再结晶

用热压缩试验方法研究了３２Ｍｎ－７Ｃｒ－１Ｍｏ－０．３Ｎ奥氏体钢的动态再结晶。结果表明，在１１５０℃变形时，奥氏体已完全动态再结晶；在１１００℃以下变形时，奥氏体发生部分动态再结晶。     

超低碳Cr26—Ni28—Mo5—Cu3—Nb0.35铸造不锈钢的组织和耐蚀性能

用金相、透射电子显微镜、电子探针与扫描电镜分析研究得出超低碳Ｃｒ２６－Ｎｉ２８－Ｍｏ５－Ｃｕ３－Ｎｂ０．３５不锈钢铸态组织中含有σ相，经８５０￣１１２０℃热处理均可形成σ相，包括（Ｆｅ－Ｃｒ）σ相，（Ｆｅ－Ｍｏ）σ相和（Ｃｒ－Ｎｉ－Ｓｉ）σ相，８５０℃左右有Ｍ６Ｃ型碳化物和ＮｂＣ析出。该钢经１１５０℃２ｈ水冷固溶处理后，具有优良的耐腐蚀性能。     

钛—硼和铝—硼处理对抗氢蚀1.25Cr—0.5Mo钢使用性能的影响

对Ａｌ－Ｂ或Ｔｉ－Ｂ处理的１．２５Ｃｒ－０．５Ｍｏ钢的研究结果表明：（１）Ａｌ－Ｂ和Ｔｉ－Ｂ处理明显增加了１．２５Ｃｒ－０．５Ｍｏ的淬透性，强度及塑、韧性；（２）Ａｌ－Ｂ和ＴｉＢ处理均使．２５Ｃｒ－０．５Ｍｏ钢的抗氧性能明显提高，当Ｂ含量相当时，Ｔｉ－Ｂ处理钢的抗氢蚀性能优于Ａｌ－Ｂ处理钢；（３）Ｂ含量较高时，钢的抗氧蚀性能较强，但塑、声望生及回火性能却相对较差，因此，较低含量Ｂ处理更有利于材料综     

热处理对0Cr13Ni4Mo马氏全不锈钢组织和性能的影响

在９５０～１０５０℃温度范围内，提高０Ｃｒ１３Ｎｉ４Ｍｏ钢的淬火温度则增大马氏体板条的尺寸，但对性能无明显影响。回火对钢中有残余奥氏体析出，６３０℃为析出峰此时抗拉强度降低，二次回火能降低钢的屈强比。     

Evolution and Coarsening of Carbides in 2.25Cr-1Mo Steel Weld Metal During High Temperature Tempering

Transformation and coarsening of carbides in 2.25Cr-1Mo steel weld metal during tempering at 700 ℃ for different time intervals ranging from 1 to 150 h were examined by transmission electron microscopy and scanning electron microscopy. M3C carbides were observed in the as-welded specimens and when tempered, the precipitates were mainly composed of M3C, M7C3, and M23C6 carbides. A sequence for corresponding carbide transformation during tempering with initial precipitation of M3C and the subsequent precipitation of M7C3 and M23C6 was proposed. The precipitation of M7C3 with higher chromium content was the main factor contributing to the decrease in coarsening rate of precipitates after prolonged tempering. The decrease in hardness of the tempered specimens agreed well with the prediction of the weakening of precipitation strengthening owing to the coarsening of carbides.     

Tempering Behavior of 45Cr-2W-0.25V Steel

 In this research the tempering behavior of a Cr-W-V steel was investigated. This new alloy with the composition of Fe-4.5Cr-2W-0.25V-0.1C was austenitized at 1000°C for 30 min and tempered at 500°C to 700°C for different times up to 100h. An OM analysis of the microstructure of air cooled and water quenched specimens before tempering showed that although in both conditions fully martensitic matrix formed, finer structure had formed in the water quenched specimens. The XRD and TEM results showed that the most stable carbides formed during tempering of the steel were M23C6 and M7C3, respectively. Other carbides such as M3C and M2C, formed in the first stages of tempering, and stable MC were also observed. The results showed that when the tempering time, temperature and cooling rate were increased, weight percent of extracted precipitates was increased. In addition, the formation rate of the stable carbides such as M23C6 and dissolution rate of the metastable carbides such as M3C and M2C were increased. The hardness results was revealed that tempering at 600°C and 700°C result in gradual decrease in hardness, but didn't observed significant changes in hardness at 500°C even for long tempering times.     

Tempering Behavior of 4.5Cr-2W-0.25V Steel

The tempering behavior of a Cr-W-V steel was investigated in this research.This new alloy with the composition of Fe-4.5Cr-2W-0.25V-0.1C was austenitized at 1000 ℃ for 30 min and tempered at 600 and 700 ℃ for different time up to 100 h.An OM analysis of the microstructure of air cooled and water quenched specimens before tempering showed that although under both conditions fully martensitic matrix formed,finer structure had formed in the water quenched specimens.The XRD and TEM results showed that the most stable carbides formed during tempering of the steel were M23C6 and M7C3,respectively.Other carbides such as M3C and M2C,formed in the first stages of tempering,and stable MC were also observed.The results showed that when the tempering time,temperature and cooling rate were increased,mass percent of extracted precipitates was increased.In addition,the formation rate of the stable carbides such as M23C6 and dissolution rate of the metastable carbides such as M3C and M2C were increased.     

Effects of tempering on the carbon activity and hydrogen attack kinetics of 2.25 Cr-1 Mo steel

The variation with tempering of the carbon activity and the Hydrogen Attack rates of a Q&T 2.25 Cr-1 Mo steel (A542 C13) was studied at 550 °C. A highly sensitive capacitance dilatometer was used to measure the HA strain rates as a function of hydrogen pressure, and an equilibration technique was used for the carbon activity. Both the carbon activity and the HA strain rate decreased monotonically with the extent of tempering. A strong correlation existed between carbon activity and the HA strain rate of the samples. Excessive tempering beyond the commercial practice did not eliminate HA, and the carbon activity of a sample tempered for 500 hours at 700 °C was as high as 0.05. The high carbon activity of the excessively tempered samples is explained as due to the effects of low Cr/Fe ratio in M₂₃C₆ carbides and to less than the equilibrium Cr content next to the M₂₃C₆ resulting from the low diffusivity of Cr in α-iron at the tempering temperature of 700 °C. The methane pressure dependence of the HA strain rates suggests a grain boundary diffusion controlled growth of bubbles for hydrogen pressures up to 20 MPa at 550 °C.     

Tempering of 2.25 Pct Cr-1 Pct Mo Low Carbon Steels

The effect of carbon level on the tempering behavior at 700°C of 2.25 pct Cr-1 pct Mo steels having typical weld metal compositions has been investigated using analytical electron microscopy and X-ray diffraction techniques. The morphology, crystallography and chemistry, of each of the various types of carbides observed, has been established. It has been shown that each carbide type can be readily identified in terms of the relative heights of the EPMA spectra peaks for iron, chromium, molybdenum, and silicon. A decrease in the carbon level of the steel increases the rate at which the carbide precipitation reactions proceed, and also influences the final product. Of the carbides detected, M₂₃C₆ and M₇C₃ were found to be chromium-based, and their compositions were independent of both the carbon level of the steel and the tempering time. The molybdenum-based carbides, M₂C and M₆C, however, showed an increase in their molybdenum contents as the tempering time was increased. The rate of this increase became greater as the carbon content of the steel was lowered.     

Microstructure Evolution and Precipitation Behavior of 0Cr16Ni5Mo Martensitic Stainless Steel during Tempering Process

The microstructure,morphology of precipitates and retained austenite and the volume fraction of retained austenite in 0Cr16Ni5 Mo stainless steel during the tempering process were analyzed using optical microscope(OM),transmission electron microscope(TEM),X-ray diffraction(XRD)and scanning transmission electron microscope(STEM).The results show that the microstructure of the tempered steel is mainly composed of tempered martensite,retained austenite,and delta ferrite.In the case of samples tempered from 500 to 700 ℃,the precipitates are mainly M_(23)C_6,which precipitate along the lath martensite boundaries.The precipitate content increases with the tempering temperature.During the tempering process,the content of retained austenite initially increases and then decreases,the maximum content of retained austenite being 29 vol.% upon tempering at 600 ℃.TEM analysis of the tested steel reveals two morphology types of retained austenite.One is thin film-like retained austenite that exists along the martensite lath boundary.The other is blocky austenite located on packet at the boundary and the original austenite grain boundary.To further understand the stability of reversed austenite,the Ni content in reversed austenite was measured using STEM.Results show a significant difference in nickel concentrations between reversed austenite and martensite.     

Microstructure and mechanical properties of a 3Cr-1.5Mo steel

Tensile and impact properties were determined for a steel (3 wt pct Cr-1.5 wt pct Mo-0.1 wt pct V-0.1 wt pct C) considered a candidate for elevated-temperature pressure-vessel applications. The steel was tested in two heat-treated conditions: normalized and tempered and quenched and tempered for various tempering conditions. Similar tempering treatments for the quenched and the normalized steels led to similar strengths. However, for the lowest tempering parameter used, the impact properties for the quenched-and-tempered steel exceeded those for the normalized-and-tempered steel, resulting in an excellent ductile-brittle transition temperature (-70 °C) and upper-shelf energy (225 J) for the quenched-and-tempered steel at a high strength (770 MPa ultimate tensile strength). Further tempering reduced the strength for the steel in both heat-treated conditions. The impact properties of the quenched steel were only slightly changed by further tempering, but those for the normalized steel improved, eventually equaling those for the quenched-and-tempered steel. The difference in impact properties after the two heat treatments was attributed to a difference in bainite microstructures.     

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.     

时效温度对14Co-11Ni-2Cr-3Mo超高强度钢组织与性能的影响

研究了25 kg感应炉熔炼的Co-Ni-Cr-Mo二次硬化超高强度钢(％:0．16C、11．0Ni、2．0Cr、3．0Mo、14．0Co)经460-580℃时效后的组织和力学性能。试验结果表明,该钢经860℃淬火+(-73℃)冷处理+480℃时效后,组织中存在大量弥散分布的针状M(Co,Mo)₂C碳化物,钢的屈服强度Rp_0.2达到最大值1 685 MPa,冲击功A_kv为20 J;在550℃过时效状态下,板条边界逆转变奥氏体量明显增加,A_kv增至32 J,同时Rp_0.2下降至1 320 MPa。     

Precipitation of nanoscale carbides in Ti- Mo microalloyed steel during tempering process

The distribution, morphology and size of the carbide precipitates in as- rolled and as- tempered Ti- Mo microalloyed steels were elucidated by optical microscopy and transmission electron microscopy. The change in nanoscale precipitate during tempering and its effect on strength of test steel were analyzed by tensile test. The results revealed that substantial improvement in yield strength occurred on tempering at 600?? for 2 h because of the supersaturated precipitation and homogeneous distribution of profuse (Ti, Mo)C carbide in the matrix in average size from 5-6nm except interphase precipitation, and the precipitation volume fraction of the sample tempered at 600?? exhibited an approximate 3%-5% increase compared to the samples tempered at 650 and 700??. With increase in tempering temperature and holding time, the interphase- precipitated carbides were observed to have slightly coarsened to a maximum size of less than 8nm, but did not coarsen as much as the supersaturated carbides formed during tempering. The interphase precipitation exhibits more excellent behavior of thermal stability than supersaturated precipitation during tempering process.