Present quality level of large heat resistant rotor forgings made of 1% CrMoV steel – Part II

While in part I mainly mechanical and toughness properties together with structural aspects have been dealt with now design properties are described. The basic properties for heat resistant rotor materials are traditionally the creep properties. So they are here investigated more in detail and it is shown that modern 1% CrMoV rotor steels have a quite similar creep behaviour both oil and air quenched. Long term high temperature exposure and its influence on the properties are as well mentioned as heat stability behaviour.     

电阻焊接用高强Q125级石油套管钢组织及其性能

设计了一种低合金含量的Q125级高强度石油套管用钢,研究了热处理工艺对实验钢组织和力学性能的影响.与870℃淬火+500℃回火工艺相比,实验钢在850℃淬火+500℃回火工艺下具有更好的强韧性配合.与870℃淬火相比,850℃淬火处理的奥氏体晶粒尺寸较小,使决定钢力学性能的晶区、板条束尺寸细化,因此其性能更优异.淬火温度对实验钢的析出行为影响不大.尺寸较大的TiN以及TiC和TiN复合析出物对奥氏体晶界起到钉扎作用,可以抑制奥氏体晶粒的长大;含有Mo的尺寸较小的TiC可以起到钉扎位错的作用,阻止位错移动,对强度的提高贡献很大.      

回火工艺对COST-FB2转子钢组织与性能的影响

摘要：利用OM、SEM和TEM等手段研究了回火工艺对COST FB2转子钢的显微组织与力学性能的影响,结果表明：570℃一次回火后,马氏体板条内有杆状Fe3C和细小颗粒状的MX,板条界有少量颗粒状碳化物析出;700℃二次回火后,板条内杆状Fe3C和板条界上颗粒状碳化物消失或转变成M23C6型碳化物。经570℃一次回火,COST FB2转子钢试样的强度较高,冲击功较低,再经700℃回火强度略有降低,冲击功增加。经不同温度的2次回火的调整,COST FB2转子钢试样获得了较好的强韧性配合。     

The effect of heat treatment on microstructure and mechanical properties in 52100 steel

An investigation was carried out to study the microstructure and mechanical properties of isothermally transformed AISI E 52100 steel. Heal treatments consisting of single and two cycle austenitization followed by isothermal holding resulted in duplex structures of martensite and bainite. In addition, high temperature austenitization led to large amounts of retained austenite at room temperature. Conventional oil quenching treatments were also performed for purposes of comparison. It was found that isothermal holding aboveM _s after single cycle austenitization resulted in a microstructure which had strength and toughness properties equivalent to quenched and tempered 52100. The two cycle austenitization treatment followed by isothermal holding led to a doubling of the fracture toughness at equivalent hardness and ultimate tensile strength levels relative to the properties of conventional quenched and tempered 52100 steel. The mechanical stability of retained austenite, present after two cycle austenitization, was examined. Although it was found that the presence of unstable retained austenite was associated with the best combination of strength and toughness, it cannot be unequivocally stated that the retained austenite influenced the mechanical properties. R. M. HORN, formerly with University of California, Berkeley     

06Ni9钢热处理工艺对组织性能的影响

因06Ni9（w（Ni）为9％）钢在不同的热处理条件下性能变化较大,则研究了二次淬火时06Ni9的微观组织结构,分析了组织演变规律及其对性能的影响。研究结果表明06Ni9钢二次淬火加回火后冲击韧性稳定提高,是由于残余奥氏体和组织结构稳定导致的双重效果。     

奥氏体化温度对30Cr3SiMnNiWMo钢组织性能的影响

试验研究了860～980℃奥氏体化处理对30Cr3SiMnNiWMo钢(%:0.28C、0.74Mn、1.04Si、2.70Cr、1.15Ni、0.45Mo、1.04W、0.07V、0.05Al)组织以及260℃回火后钢的力学性能的影响。结果表明,30Cr3SiMnNiWMo钢860～920℃淬火组织中存在大量M6C碳化物,对回火钢的韧性不利;950℃淬火后,钢中M6C碳化物基本溶解,原奥氏体晶粒开始长大,回火后钢的强度降低;30Cr3SiMnNiWMo钢经920℃1h油淬+260℃2h回火可以获得具有少量残余奥氏体和未溶碳化物的板条马氏体组织,并具有优良的强韧性(Rm=1680 MPa, Rp0.2=1330 MPa,A=13%, Z=58.5%, AKU=85 J) 。     

回火对20SiMn3NiA钢组织和力学性能的影响

研究了20SiMn3NiA钢860℃正火,900℃40 min油淬,180～650℃90～150 min回火的组织和力学性能。结果表明,该钢较佳的回火温度为200～250℃,230℃回火后得到板条马氏体、细棒状碳化物析出相和残余奥氏体,在250℃回火时该钢的抗拉强度(Rm)超过1 500 MPa,冲击韧性(AKY)超过80 J,有较好的强韧性匹配。20SiMn3NiA钢在320℃中温回火时,碳化物析出相呈连续的片状分布,使得该钢的冲击韧性值很低,当在320～600℃区间回火时,20SiMn3NiA钢具有明显的回火脆性。     

Effect of tempering on mechanical properties of 25Co15Ni11Cr2MoE steel

The change rule of mechanical properties and impact fracture morphologies of a high Co- Ni secondary hardening ultra- high strength 25Co15Ni11Cr2MoE steel tempered at 200-750?? after quenched was studied by mechanical properties test and microstructure analysis such as optical microscope(OM) and scanning electron microscope(SEM). The results show that experimental steel after quenching and tempering has a remarkable secondary hardening effect. After tempered at 400-495??, the hardness of experimental steel can reach and beyond the quenched hardness. In this range, tensile strength, yield strength and hardness of experimental steel increase with the tempering temperature increasing, tensile strength and hardness of experimental reach maximum (57. 3HRC and 2160MPa) after tempered at 470??, meanwhile, with the tempering temperature increasing, impact toughness of experimental steel decreases during the prophase, until reaches minimum at 430??, then increases gradually, and reaches maximum after tempered at 510??. The recommended optimum heat treatment process of 25Co15Ni11Cr2MoE steel is as follow: 950???1h oil quenching??(-73??)??1h rising back to room temperature in the air ??495???5h air cooling. At this time, the experimental steel has the best strength and toughness matching.     

Heat treatment process of 30CrMo hot rolled steel produced by CSP process

The effect of heat treatment processes on microstructure and mechanical properties of 30CrMo hot rolled steel produced by CSP (compact strip production) process were investigated. The results show that the martensite is obtained in the experimental steels by oil quenched from 900?? after holding for 15min and 60min. And the samples which oil quenched from 900?? after holding for 15min have the better mechanical properties after tempering at different temperatures. With the increase of tempering temperature, the decomposition of martensite accelerated that resulted in the lath character of martensite gradually disappeared and the precipitation of cementite in matrix. When the tempering temperature increased from 200?? to 600??, the tensile strength decreased from 1744MPa to 949MPa and the hardness of the experimental steel decreased from 50. 8HRC to 35. 3HRC.While the elongation first decreased and then increased, the yield strength first increased and then decreased. When the tempering temperature is 300??, the experimental steel has the maximum yield strength and theminimum elongation which are 1421MPa and 7. 5%, respectively. Moreover, the model was developed to predict the hardness of experimental steel after tempered at different temperatures for 120min. The calculated results were in good agreement with the experimental results.     

回火温度对中碳合金钢4Cr5MoSiV1Nb组织和性能的影响

 为了优化合金性能，研究了回火温度对中碳合金钢4Cr5MoSiV1Nb组织和性能的影响。试验结果表明，4Cr5MoSiV1Nb合金钢的二次硬化温度区间为300～550 ℃，峰值出现在550 ℃，此时硬度值为56.3HRC，同时伴有冲击韧性的显著降低，冲击韧性降低的原因是合金钢回火时含铬铬的细短棒状合金渗碳体在晶界析出，可以推测减少淬火合金钢中铬的偏析将会减少晶界析出，提高冲击韧性。微量铌的加入形成了（V，Nb）C强化相颗粒。合金在250～350 ℃回火综合性能最佳，可以达到冲击韧性15 J/cm2、硬度55HRC以上。     

Effect of heat treatment on the fracture toughness of hot-rolled corrosion-resistant austenitic high-nitrogen 0.4Cr20Ni6Mn11Mo2N0.5 steel

The effect of water quenching from rolling heating at 1100°C on the structure, the mechanical properties, and the static fracture toughness of corrosion-resistant austenitic high-nitrogen 0.4Cr20Ni6Mn11Mo2N0.5 steel shot-rolled at 1100–900°C is studied. It is found that, after quenching, the initially hot-deformed steel possesses a quite high fracture toughness, although quenching from 1100°C decreases its fracture toughness by 11.4%. An analysis of fracture surfaces indicates a ductile character of failed quenched steel specimens. The specimens have fracture regions close to a quasi-cleavage at the stage of stable crack growth.     

The effect of step quenching on the microstructure and fracture toughness of aisi 4340 steel

The microstructure and fracture toughness of AISI 4340 steel in the direct and in the step quenched and tempered condition has been studied. Austenitizing temperatures of 1473 K followed by step quenching to either 1373 or 1143 K prior to oil quenching have been employed. A consistent drop in the fracture toughness values was observed as the intermediate holding temperature decreased or the holding time at this temperature in-creased. A concurrent increase in the amount of twinning was seen without any change in the amount and/or distribution of retained austenite. While direct evidence for segre-gation has not been found, the observed facts are consistent with segregation effects during the austenitizing treatment.     

热处理对超级13Cr不锈钢组织及拉伸性能的影响

 为了研究热处理工艺对超级13Cr不锈钢组织及拉伸性能的影响,采用了光学显微镜、X射线衍射仪、透射电子显微镜、显微硬度测试及应变速率拉伸等试验方法。结果表明,经过水淬和油淬处理的超级13Cr不锈钢组织及拉伸性能相差不大。但相比于水淬,采用油淬的试样经回火处理后塑性得到更大提升。淬火试样经回火处理后,组织变为回火索氏体。随着回火温度升高,材料的塑性先增加后减小,硬度与强度变化则相反。620 ℃回火试样含有逆变奥氏体,强度塑性组合较好。二次回火能够增加超级13Cr不锈钢中逆变奥氏体含量,但塑性变化不明显,强度下降较大。     

高强度螺栓钢的研制与应用

研究了新型高强度螺栓钢的化学成分、组织和性能,采用淬火＋低温回火或淬 火炉同温回火热处理工艺,钢的强度、塑性和韧性都有很好的配合。用新型高强度螺栓钢制作的2500四辊可逆式轧机万向接轴联接螺栓,具有很高的使用寿命。     

轧制比和Nb对V-Ti微合金非调质钢组织及性能的影响

通过金相、扫描、透射电镜研究不同轧制比工艺下V-Ti、Nb-V-Ti两种微合金化非调质钢的微观组织及机械性能。结果显示:Nb-V-Ti非调质钢轧制比大于10时,冲击韧性值可以达到50 J,而V-Ti非调质钢的轧制比却需要大于15以上,才能达到类似的冲击韧性值。从相同轧制比对比也可以发现,Nb-V-Ti非调质钢的冲击性能明显优于V-Ti非调质钢,这是因为Nb能够显著提高非调质钢的奥氏体粗化温度,有效阻止奥氏体晶粒的快速长大,细化非调质钢晶粒,降低珠光体片层间距,使渗碳体呈粒状或球状分布;另外,Nb能促进V-Ti非调质钢中细小含铌碳化物的弥散析出,细化基体组织,同时提高非调质钢的强度。因此,Nb-V-Ti复合非调质钢经过未再结晶区变形后可获得均匀细小的铁素体-珠光体组织,且在900℃未再结晶区进行大轧制比变形能够有效改善Nb-V-Ti非调质钢的强韧性。     

Relationship Among Microstructure and Properties and Heat Treatment Process of Ultra-High Strength X120 Pipeline Steel

 The variation of heat treatments including directed quenching and tempering off-line after controlled rolling (DQT) and quenching off-line and tempering off-line after controlled rolling (RQT) with microstructure and mechanical properties of a low-carbon microalloyed steel was compared and analyzed. For DQT, the quenched steel was obviously banded microstructure, with increasing tempering temperature, lath martensite coarsened, the cusp carbide precipitated at grain boundaries, the yield strength fluctuated slightly, and the fracture-separation was obvious. The impact toughness was better in the steel tempered at 500 ℃ for 1 h. In RQT, with increasing tempering temperature, lath martensite degenerated, intragranular and intergranular finer precipitations with smaller than 30 nm precipitated and grew up and were distributed dispersedly, the stripe-like carbides were distributed at grain boundaries, and the yield strength and tensile strengthen decreased obviously. The impact toughness of RQT process was much better than that of DQT process, and the comprehensive mechanical properties were better for the steel tempered at 500 ℃ for 1 h of RQT process.     

Microstructure and Mechanical Properties of Martensitic Stainless Steel 6Crl5MoV

 Martensitic stainless steel containing Cr of 12% to 18% (mass percent) are common utilized in quenching and tempering processes for knife and cutlery steel. The properties obtained in these materials are significantly influenced by matrix composition after heat treatment, especially as Cr and C content. Comprehensive considered the hardness and corrosion resistance, a new type martensitic stainless steel 6Cr15MoV has been developed. The effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel is emphatically researched. Thermo-Calc software has been carried out to thermodynamic calculation; OM, SEM and TEM have been carried out to microstructure observation; hardness and impact toughness test have been carried out to evaluate the mechanical properties. Results show that the equilibrium carbide in 6Cr15MoV steel is M23C6 carbide, and the M23C6 carbides finely distributed in annealed microstructure. 6Cr15MoV martensitic stainless steel has a wider quenching temperature range, the hardness value of steel 6Cr15MoV can reach to HRC 608 to HRC 616 when quenched at 1060 to 1100 ℃. Finely distributed carbides will exist in quenched microstructure, and effectively inhabit the growth of austenite grain. With the increasing of quenching temperature, the volume fraction of undissolved carbides will decrease. The excellent comprehensive mechanical properties can be obtained by quenched at 1060 to 1100 ℃ with tempered at 100 to 150 ℃, and it is mainly due to the high carbon martensite and fine grain size. At these temperature ranges, the hardness will retain about HRC 592 to HRC 616 and the Charpy U-notch impact toughness will retain about 173 to 20 J. A lot of M23C6 carbides precipitated from martensite matrix, at the same time along the boundaries of martensite lathes which leading to the decrease of impact toughness when tempered at 500 to 540 ℃. The M3C precipitants also existed in the martensite matrix of test steel after tempered at 500 ℃, and the mean size of M3C precipitates is bigger than that of M23C6 precipitates.     

配分过程对热轧直接淬火配分钢拉伸性能及冲击韧性的影响

基于一种低碳硅锰系成分,结合热轧直接淬火配分工艺,开发了一种厚规格热轧直接淬火配分钢,研究了配分过程对实验钢微观组织,力学性能和冲击韧性的影响.用SEM、XRD、TEM分析观察材料的微观组织.研究结果显示,实验钢抗拉强度为1 080~1 400 MPa,屈强比为0.6~0.79,强塑积高达28 000 MPa%.等温配分钢的低温冲击韧性较动态配分钢更好,并且随着冲击温度的降低,等温配分钢冲击功比动态配分钢下降更慢.实验钢残余奥氏体含量(体积分数)为16%-28%,碳质量分数为1.05%-1.35%.同时等温配分钢较动态配分钢具有更高的残余奥氏体含量和更低的残余奥氏体碳含量.     

800MPa级高强钢调质工艺的研究

针对1种800MPa级高强钢的调质过程,分析了不同淬火温度和回火温度对实验钢力学性能和组织的影响。结果表明：淬火温度在880～920℃之间时,随着淬火温度升高,实验钢的强度逐渐降低,-40℃冲击韧性是先升高后降低,并在900℃达到最大;回火温度在550～700℃之间,随着回火温度的升高,实验钢的强度逐渐下降,-40℃冲...     

回火温度对30Cr15Mo1N微观组织和力学性能影响

 为探索高氮马氏体钢在回火过程中组织性能演变，对30Cr15Mo1N高氮钢进行了不同温度下的回火处理，利用OM、XRD、拉伸、冲击、SEM和TEM等方法研究了高氮钢在回火过程中微观组织和力学性能的变化规律。结果表明，30Cr15Mo1N钢经淬火和低温处理后在150～700 ℃回火，随回火温度升高，显微组织中马氏体基体逐渐发生回复与再结晶，组织中马氏体形态逐渐消失，碳氮化物先在马氏体板条边界呈片状或棒状析出，逐渐演变为颗粒状弥散分布，700 ℃时碳氮化物聚集长大、球化。随着回火温度升高，30Cr15Mo1N钢的基体持续软化，析出强化不断增强，导致其在500 ℃以下回火时强度变化较小，抗拉强度保持在2 000 MPa以上；当回火温度大于500 ℃时，强度随回火温度升高而线性下降。随着回火温度升高，30Cr15Mo1N钢的U型缺口冲击吸收功先基本保持不变再持续升高，在700 ℃回火后冲击韧性达到45 J/cm2。不同回火温度下冲击性能的变化与其强度、塑性变化密切相关，冲击韧性好坏主要由塑性大小决定。