化学成分和组织对23MnCrNiMo钢冲击韧性的影响

煤机链条用钢23MnCrNiMo轧材经淬火后于400℃回火，冲击功偏低，多数Ak≤80J。经 降低钢中有害元素含量及控制Mn含量为1．4％－1．5％，Ni含量为1．0％－1．05％和消除钢中铁素体带状组织，可使钢的A k≥90J。     

履带链轨节用钢35MnBM的研制

用EBT EAF-LF工艺试制了履带链轨节用钢35MnBM(0．36C，1．28Mn，0．0018B，0．05Ti)，测定了该钢的相变临界点和奥氏体连续冷却转变曲线。35MnBM钢845℃40min淬火，470℃ 2h回火的组织为屈氏体，σb为1060—1110MPa，δ12％—16％，Ak71—102J，末端淬透性J1.5 HRC51．5—54．5，J9 HRC47—51．5，J15 HRC32．5—45．0，该工艺所生产的35MnBM钢材各项质量指标均达到标准要求。     

铈对5CrNiMo模具钢力学性能的影响

通过研究在5CrNiMo模具钢中添加不同量稀土Ce后的强度、塑性和弹性模量的变化,对5CrNiMo模具钢的低周疲劳寿命进行了估算.结果表明:稀土Ce添加量在适当的范围内可显著提高强度和塑性,并且当稀土Ce添加量为0.20%(质量分数)时,5CrNiMo钢的强度、塑性达到最好,比不添加稀土Ce的5CrNiMo钢在相同断裂循环数N′f=100时,总应变范围ΔεT提高61.2%.     

稀土在低硫钢中的作用规律

研究了稀土对低硫（Ｓ〈０．００５％）钢性能和组织的影响，研究结果表明，稀土元素的加入可大大改善钢的冲击韧性，而不影响钢的组织类型，但可使钢中铁素体数量增加，珠洮体数量减少，晶粒度级别略有提高。     

混合稀土(La-Ce)对30MnCrNiMo钢组织与性能的影响

为了改善30MnCrNiMo钢板的综合力学性能，向钢中加入微量混合稀土元素，借助全自动淬火膨胀仪测定钢的相变点，制定了钢的热处理工艺，通过显微组织观察及冲击、拉伸性能测试，研究了含稀土与不含稀土两组试验钢的组织与力学性能。结果表明，加入混合稀土La-Ce后，提高了钢的A_c1、A_c3相变点温度，降低了钢的B_s、B_f相变点温度，提升了钢的贝氏体的显微硬度，改善了回火马氏体组织、细化了奥氏体晶粒，变质了钢中夹杂物，提升了钢的冲击性能和拉伸性能，室温冲击功和-40℃低温冲击功分别提升了16.8%和17.4%,抗拉强度、屈服强度和断后伸长率分别提升了15.2%、4.5%和8.3%。     

淬-回火温度对高强度钢30NCD16组织和性能的影响

试验了电渣重熔高强度钢30NCD16(％:0．31C、1．41Cr、4.01Ni、0．52Mo)840-930℃淬火、350-625℃回火时的组织和力学性能。结果表明,高强度钢30NCD16最佳热处理工艺为840-870℃淬火+560℃回火,可获得细致均匀的索氏体组织,钢的抗拉强度≥1 200 MPa,冲击功A_KU5≥50 J。     

影响40MnNbRe气瓶钢的组织和性能的热处理工艺的研究

采用不同的热处理工艺处理40MnNbRe气瓶钢，研究发现：加入铌和稀土元素后，不同的热处理工艺对40MnNbRe钢的组织和力学性以胶生较大影响。适宜的淬火＋回火工艺能够使该钢的低温冲击韧性可提高两部以上，并且也使屈服强度明显提高。     

热处理工艺对30CrA钢的组织和力学性能的影响

本文主要研究了一种新型低合金超高强度钢30CrBA钢，通过采用非真空感应炉 电渣重熔的先进冶炼方法，生产出了合格的试验料。通过进行不同温度淬火和回火后，进一步研究其力学性能和微观组织变化规律。实验结果发现：在830～87012淬火、200℃回火时，30CrBA钢的组织为均匀细小的回火马氏体，其力学性能分别达到：σ1≥1700MPa、σ0.2≥1300MPa、σ5≥12％、ψ≥45％、Ak≥80J。     

Mn2钢低温韧性变化规律研究

对Mn2钢在不同热处理工艺、不同试验温度和不同试样状态下的冲击韧性进行了详细的分析,结果表明:CM690钢在900℃保温90 min水冷淬火,600℃保温90 min水冷回火,在保证钢材的强度满足要求的情况下,可获得良好的韧性;淬火水温超过30℃时,因钢的淬透能力下降,会强烈地降低钢的强度和韧性;钢中加入0.015%~0.025%的Ti,提高冲击韧性值35~40 J;对于CM490钢,若轧后空冷或堆冷,由于冷却速度较低,会获得铁素体+珠光体+贝氏体的混合组织,不利于提高钢材的韧性,而正火后其组织为铁素体+贝氏体,其冲击值比前两种状态高3~5倍。     

PD3钢轨钢接触疲劳行为研究

在最大接触应力为１３４１ＭＰａ、滑差率为１０％及油润滑的试验条件下，对在线全长余热淬火、热轨及稀土处理三种状态的ＰＤ３钢轨钢的接触疲劳行为进行了测定。通过对失效试样的分析，对钢轨钢的接触疲劳机制进行了探讨。试验结果表明，在线全长余热淬火工艺大大提高了ＰＤ３钢轨钢的接触疲劳抗力。     

Effects of Lanthanum on Mechanical Properties of 5CrNiMo Forging Die Steel

The alteration of the strength, hardness and impact ductility of 5CrNiMo steel using three different additions of RE La element is studied in this paper. The mechanical properties of 5CrNiMo steel with RE La additions are be compared with that of the 5CrNiMo steel on the same heat-treatment condition without RE La element addition. The results show that the strength. hardness and impact ductility of 5CrNiMo steel will be improved obviously when the content of RE La element is proper, and as the content of RE La element is 0.033% (mass fraction), the 5CrNiMo steel has the best mechanical properties.     

Kinetics of Formation of Large-Dimension Rare Earth Inclusion in Steels

The elemental distribution within the large-dimension rare earth inclusion in steels was studied through analysis on plane distribution of elements by EPMA (Electron Probe Microanalyzer). The kinetics and mechanism of formation of RE inclusion were discussed, taking 5CrNiMo steel with the addition of RE and other microalloying elements as example. RE inclusions nucleate on oxides and sulphides with high melting point and grow up separately, then integrated by relatively high surface activity, which is a particular characteristic of RE elements, in liquid phase and during the course of solidification. Finally, the fine and dispersed RE inclusions merge and grow into a large-dimension one.     

Role of non-metallic inclusions in heat-treated steels for sour environment

Sulphide stress corrosion cracking (SSCC) studies on a set of three steels with different inclusion morphologies were conducted. Effect of heat treatment of the steels with and without rare-earth metal (RE) treatment upon SSCC resistance was studied. Threshold stress, corrosion rate and hydrogen content in the steels were determined. Quenched and tempered structure was found to improve the SSCC resistance only when the steel is RE treated. Corrosion rate and hydrogen content in the steels were found to decrease as the inclusion morphology is changed from elongated stringers to globular shape, which improves the SSCC resistance.     

Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth （RE） amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2% in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10^-6 -10^-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0.10%-0.20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0. 2% which leads to a largely improved high temperature mechanical property.     

稀土对42CrMoTiB钢夹杂物和力学性能的影响

试验42CrMoTiB钢和稀土微合金化42CrMoTiBRE钢(/%:0.41～0.43C、0.36～0.38Si、0.59～0.72Mn、0.018～0.020P、0.005～0.010S、1.08～1.13Cr、0.16～0.19Mo、0.06～0.08Ti、0.003～0.004B、0～0.020Ce或Sm,0.001 3～0.001 5T[O])由150 kg真空感应炉冶炼,浇铸成平均断面尺寸165 mm×165 mm的钢锭,锻成120mm×120 mm钢坯。研究了Ce或Sm对42CrMoTiB钢锻坯夹杂物和力学性能的影响。结果表明,与未加稀土42CrMoTiB钢相比,加入0.18RE后(钢中RE含量0.019%～0.020%)42CrMoTiBRE钢中的夹杂物含量大幅降低,A类、B类和D类粗系夹杂级别分别由0.5、2.0和0.5降低至0、0～0.5和0,细系夹杂分别由0.5、1.5和2.0降低至0、1.0和1.0。加入RE改变了钢中夹杂物形貌,形成球形稀土硫氧化物;加稀土明显提高钢的塑性和韧性,与42CrMoTiB钢相比42CrMoTiBCe钢横向断面收缩率(Z)和夏比冲击功(A_KV)分别由22%和17 J/cm²提高至30%和28 J/cm²。      

Evolution of Pearlite Microstructure in Low-Carbon Cast Microalloyed Steel Due to the Addition of La and Ce

The effects of rare earth elements (RE) addition on the pearlite microstructure in low-carbon microalloyed steels have been investigated under two heat treatment conditions: (1) a normalizing treatment (as a conventional heat treatment used industrially to obtain the final mechanical properties of such steels), and (2) an isothermal treatment at 650 °C. This research reports the following effects due to the addition of RE: (i) refinement of the nodule and colony size of pearlite along with the ferrite grain size in the normalized condition, without a significant change in the volume fraction of pearlite. This microstructural refinement observed at room temperature is a consequence of the refinement of cast and austenitic microstructures formed during cooling in the presence of RE; (ii) the interlamellar spacing of pearlite isothermally transformed at 650 °C, as observed by SEM and TEM, is effectively reduced in the RE-added steel. This is likely due to two different effects combined: (i) direct influence of RE on atom carbon diffusion; and (ii) pearlite growth being boundary diffusion controlled by RE partitioning.     

Application of thermomechanical treatment on medium-carbon microalloyed steels continuously cooled from forging temperature

In the high-production-drop-forging of parts for automobile and truck engines the classical quench and tempering (QT) of low-alloyed steels is nowadays - in a lot of plants in Europe - substituted by direct continuous cooling (CC) of microalloyed steels without the necessity of additional heat treatment and expensive straightening as well as stress relieving cycles. Nevertheless, there are some limitations on strength and toughness achievable by this technique. On two commercial medium-carbon (0.3%C) steels microalloyed with vanadium or vanadium and titanium, modified deformation parameters were applied. The mechanical properties, determined by the tensile test, can be improved by decreasing the deformation temperature. Nevertheless, the values of yield strength (resp. 0.2%-proof stress) as well as reduction of area remain inferior to those after QT of the same steels.     

Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Mechanism of Annealing Softening of Rolled or Forged Tool Steel

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