调质工艺对Q690D钢综合力学性能及组织的影响

 以60mm厚Q690D高强度结构钢板为研究对象,在相同轧制条件下,系统地研究了淬火、回火温度对试验钢综合力学性能及显微组织的影响,并对第二相析出进行理论分析。试验结果表明：随淬火温度升高,试验钢强度升高,韧性下降;随回火温度升高,试验钢强度下降,但韧性明显升高。该钢采用930℃淬火(保温10min)650℃回火(保温40min)的调质热处理工艺具有良好的强韧性匹配,综合力学性能最佳,满足国标GB/T 16270—2009要求。     

Impact Toughness of an NM400 Wear-Resistant Steel

An NM400 wear-resistant steel was hot rolled and then the plates were heat-treated by direct quenching and tempering (DQT) and reheat quenching and tempering (RQT) techniques, respectively. The Charpy impact test was carried out with an instrumented Charpy impact tester. The microstructure and fracture surface were investigated by a combination of optical microscopy, transmission electron microscopy and scanning electron microscopy methods. It was found that the impact toughness of DQT specimen was much higher than that of RQT specimen. The microstructure of both DQT and RQT specimens was characterized by a mixture of tempered lath martensite and lower bainite. The lower bainite in DQT specimen extended into prior austenite grains and the content was higher than that in RQT specimen. The lower bainite in DQT specimen improved the impact toughness by increasing the proportion of large-angle boundaries and relieving the stress concentration at the crack tip. A number of fine and dispersed carbides in DQT specimen also contributed to the improvement of the impact toughness.     

淬火工艺对马氏体高强钢组织和性能的影响

摘要：采用拉伸、冲击、金相、电子背散射衍射、透射电镜、X射线衍射等试验手段,研究了在线直接淬火+回火（DQT）与离线再加热淬火+回火（RQT）工艺对马氏体高强钢组织性能的影响。结果表明,2种试验钢组织均为板条马氏体,RQT试验钢原奥氏体晶粒及板条束呈等轴状,板条块较短,板条较宽,DQT试验钢原奥氏体晶粒呈扁平状,板条束贯穿整个晶粒,板条块呈细长状,板条宽度较小;位错强化是DQT试验钢强度较RQT高的主要原因;板条束为控制DQT和RQT试验钢韧性的最小单元;DQT试验钢大角晶界比例较低,其具有较大的马氏体板条束尺寸以及更高的位错密度,断裂应力较低,低温韧性较差。     

海洋平台用高强度齿条钢的研制

自升式海洋平台桩腿用厚规格A517Q高强度结构钢,要求具有高的强度及优良的低温冲击韧性。为了满足上述要求,在工艺上采用模铸、初轧及厚板轧制,并采用淬火加回火的调质工艺;在成分设计上,为得到回火后组织,保证高的强度和一定的淬透性能,主要通过Mo、B、Cr等元素的作用,同时加入一定数量的Ni。通过成分与相应的调质工艺配合,保证A517Q钢具有高的强度、高的冲击韧性及良好焊接性能。宝钢生产的127、152.4 mm厚的A517Q钢板制造的齿条已经成功应用在中海油923、924自升式海洋平台。     

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...     

原始组织对690 MPa级海工钢亚温淬火后强韧性的影响

 为了稳定亚温淬火工艺与工业化生产,通过力学性能分析及显微组织观察,对比了正火+亚温淬火+回火、在线淬火+亚温淬火+回火、离线淬火+亚温淬火+回火3种热处理工艺对690 MPa级海洋工程用钢板组织性能的影响。结果表明,采用离线淬火+亚温淬火+回火工艺结果最理想,能够大幅度提高钢板的低温冲击性能和伸长率。同时,还能够获得较低的屈强比,断口形貌全部为韧窝,呈明显的韧性断裂,而且随着亚温保温时间的增加,强度逐渐提高,当保温时间达到30 min以后,强度及条片状铁素体基本不发生变化;采用直接淬火态+亚温淬火+回火虽然可以保证高强度低屈强比,但是冲击功表现较为离散,稳定性欠佳,断口形貌为混合型,以韧性断裂为主;采用正火态+亚温淬火+回火工艺效果最差,尤其是不能保证钢板低温韧性,断口形貌全部为解理,呈明显的脆性断裂,其中片条状铁素体形貌是决定优良低温冲击性能的关键因素。     

Influence of thermomechanical treatments on the microstructure and mechanical properties of HSLA-100 steel plates

The influence of thermomechanical treatment (TMT), i.e., controlled rolling and direct quenching, as a function of rolling temperature and deformation on the microstructure and mechanical properties of HSLA-100 steel have been studied. The optical microstructure of the direct quenched (DQ) and tempered steel rooled at lower temperatures (800 °C and 900 °C) showed elongated and deformed grains, whereas complete equiaxed grains were visible after rolling at 1000 °C. The transmission electron microscope (TEM) microstructure of the 800 °C rooled DQ steel showed shorter, irregular, and closer martensite laths with extremely fine Cu and Nb(C,N) precipitates after tempering at 450 °C. The precipitates coarsened somewhat after tempering at 650 °C; the degree of coarsening was, however, less compared to that of the reheat-quenched (RQ) and tempered steel, indicating that the DQ steel was slightly more resistant to tempering. Similar to the RQ steel, at a 450 °C tempering condition, the DQ steel exhibited peak strength with extremely poor impact toughness. After tempering at 650 °C, the toughness of the DQ steel improved significantly, but at the expense of its strength. In general, the strength of the DQ and tempered steel was good and comparable to that of the RQ and tempered steel, although, its impact toughness was marginally less than the latter. The optimum combination of strength and toughness in the DQ steels was achieved after 900 °C rolling with 50 pct deformation, followed by direct quenching and tempering at 650 °C (yield strength (YS)=903 MPa, ultimate tensile strength (UTS)=928 MPa, and Charpy V-notch (CVN) strength=143 J at −85 °C).     

热处理工艺对Cr17含Ni马氏体不锈钢组织及性能的影响

通过对Cr17含Ni马氏体不锈钢热处理工艺试验,研究了不同的淬火和回火温度对Cr17含Ni马氏体不锈钢（低、高倍）组织和力学性能的影响。试验结果表明：经过淬火＋高温回火处理后,材料晶粒明显细化,材料的综合力学性能得到最大提高。同时,在中温回火时,材料的强度和硬度有所提高,塑性和韧性略有降低,出现明显的中温回火脆性倾向。Cr17含Ni马氏体不锈钢的使用状态组织为索氏体,具有良好的耐蚀性能,又具有较高的强度和韧性配合。     

Effect of quenching process on microstructure and properties of DZ2 steel for high speed train axle

The effect of quenching process on the microstructure and properties of DZ2 steel used for high speed train axles is revealed by means of OM, SEM, EBSD, room temperature tensile test and low temperature impact test. The results show that after twice quenching at 850℃ and tempering at 650℃, the optimum mechanical properties of DZ2 steel were obtained. The tensile strength, yield strength, elongation after fracture and impact energy absorption at -40℃ of DZ2 steel are 874MPa, 773MPa, 24% and 222J, respectively. Moreover, the prior austenite grain, martensite packet and block are the finest, with the size of 14.9, 6.9 and 1.32μm, respectively, which are 14.3, 5.2 and 0.35μm finer than those after quenching at 950℃ and tempering at 650℃, respectively. And it is found that finer prior austenite grain boundaries, packet boundaries and block boundaries can effectively inhibit the crack propagation and improve the low temperature toughness, resulting in the ductile brittle transition temperature of DZ2 steel significantly reduced from -103℃ to -136℃.     

核电站用SA738Gr.B钢板热处理工艺研究

为满足SA738Gr.B核电站用钢较高的性能要求,在实验室试验的基础上,研究了工业化生产热处理工艺参数对钢显微组织和力学性能的影响。结果表明,钢板淬火时冷却速度5℃/s时,能够避免先共析铁素体的析出;淬火温度较高时,钢板具有更细小和均匀的板条贝氏体;随着淬火加热的保温时间延长,晶粒组织粗化且铁素体含量减少;随着回火温度的升高,晶粒粗化,同时贝氏体含量减少,铁素体含量增多;在工业化生产中,较大淬火水量下钢板的拉伸性能更优;随着回火时间的延长,钢板强度下降而冲击韧性提高。以920℃×2.0 min/mm加热、较高水量的Q2工艺淬火,并采用650℃×1.5min/mm的工艺回火,可使钢板的强韧性达到最佳匹配。     

淬火工艺对高速列车车轴用DZ2钢组织性能的影响

摘要：采用OM、SEM、EBSD、室温拉伸试验和低温冲击试验,揭示了淬火工艺对高速列车车轴用DZ2钢组织和性能的影响。研究结果表明,经850℃两次淬火和650℃回火后,DZ2钢获得了最佳的力学性能。抗拉强度、屈服强度、断后伸长率和-40℃冲击吸收能量分别为874MPa、773MPa、24%和222J。该工艺条件下原始奥氏体晶粒、马氏体板条束和板条块最为细小,其尺寸分别为14.9、6.9和1.32μm,较经950℃淬火和650℃回火后的分别细化了14.3、5.2和0.35μm,可有效抑制裂纹的扩展,提高低温韧性,韧脆转变温度由-103℃显著降低至-136℃。     

Microstructure and Abrasive Wear Behavior of Medium Carbon Low Alloy Martensitic Abrasion Resistant Steel

The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni,Mo-free low alloy martensitic abrasion resistant steel.The three-body impact abrasive wear behavior was also analyzed.The results showed that two-step controlled rolling besides quenching at 880℃and tempering at 170℃could result in optimal mechanical property:the Brinell hardness,tensile strength,elongation and-40 ℃impact toughness were 531,1 530 MPa,11.8% and 58J,respectively.The microstructure was of fine lath martensite with little retained austenite.Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2J, and the relative wear resistance was 1.04times higher than that of the same grade compared steel under the same working condition.The optimal hardness and toughness match was the main reason of higher wear resistance.     

屈服强度785 MPa低碳含铜船板钢的组织和性能

 研究了一种屈服强度大于785 MPa的船板钢,测试了其动态连续冷却相变曲线（CCT）,研究了试验钢经控制轧制+直接淬火+回火（DQ- T）工艺处理后的组织性能。结果表明,直接淬火（DQ）钢板组织为板条马氏体（LM）,回火后铜、铌元素呈弥散析出。经500 ℃回火钢板的强度最高,冲击韧性（KV2）最低。钢板经710 ℃回火,其组织为二次马氏体（SLM）+铁素体,屈服强度（Re）为810 MPa,抗拉强度（Rm）为 1 066 MPa,伸长率（A）为17%,在-80 ℃下KV2为97 J,达到最佳强韧性匹配。     

薄板坯连铸连轧低合金耐磨钢磨料磨损特性

 研制了30CrMo,50CrV4两种牌号的薄板坯连铸连轧低合金耐磨钢板,对试验钢板进行淬火和低温回火热处理,并且与传统热轧工艺生产的热轧态的45,16Mn,Q235钢对比进行低应力磨料磨损试验,研究其磨损特性。结果表明,淬火低温回火态薄板坯连铸连轧30CrMo,50CrV4钢的相对耐磨性都达到了热轧Q235钢的1.6倍以上。在低应力磨料磨损下,显微切削机制为主要磨损机制,淬火回火态薄板坯连铸连轧低合金耐磨钢具有高硬度因而具有较好的耐磨性能,并在试验钢板硬度高于450HBW以后相对耐磨性明显提高。对比两种牌号的薄板坯连铸连轧低合金耐磨钢的显微组织、硬度、韧性及耐磨性能,30CrMo钢的综合性能较好。50CrV4钢耐磨性能较好,但其冲击韧性较低。     

热处理及NbV-N微合金化对船板钢组织性能的影响

为了获得一种良好强韧性匹配的390MPa级船板钢,通过NbV-N复合微合金化及不同热处理工艺(正火+回火、淬火+回火),对实验室钢板的室温拉伸、-40℃冲击性能及钢的微观组织、析出相等进行了分析研究。结果表明,钒、铌的添加能细化晶粒,且氮质量分数的增加使得这种细晶效果更为显著,从而使得钢的强韧性,特别是冲击韧性明显提升。相比轧态,正火+回火、淬火+回火热处理后钢的力学性能均有明显提高,特别是低温韧性有明显改善,这得益于回火过程中大量微合金碳氮化物的弥散析出及钢的有效晶粒尺寸的显著细化。     

高性能渗碳轴承钢的组织与性能

 研究了热处理工艺对渗碳轴承钢组织、力学性能的影响规律,并探讨了强韧化机制。研究表明,随着淬回火温度升高和回火次数增加以及采用深冷工艺,渗碳轴承钢的强度与硬度增加,冲击韧性值下降。采用910℃淬火和180℃二次回火,轴承钢材料性能可达到硬度HRC452,抗拉强度Rm为1450MPa,屈服强度ReL为1240MPa,AKU为105J,残余奥氏体的体积分数控制在1%以下。试验钢良好的强韧性配合主要来自于晶粒的细化、超细马氏体板条和均匀弥散的细小碳化物的析出;尺寸稳定性的效果主要是残余奥氏体量的控制。     

Effect of Heat Treatment Process on Properties of 1000 MPa Ultra-High Strength Steel

 Two types of steel, C-Mn-Cr-Mo-B microalloyed steel and C-Mn-Mo-Nb-Cu-B microalloyed steel, are designed to develop 1000 MPa ultra-high strength steel. Two kinds of processes, thermomechanical controlled process (TMCP) combined with traditional off-line quenching and tempering (QT) process versus controlled rolling process (CR) combined with direct quenching and tempering (DQ+T) process, are applied. The effect of heat treatment processing mode on the microstructure and mechanical properties is studied. The relationship between microstructure and mechanical properties is investigated by SEM and TEM. After tempering at 450 to 550 ℃ for 1 h, the steel produced by TMCP+QT process shows combination of excellent strength and low temperature toughness. The yield strength is above 1000 MPa, elongation above 15% and impact energy at -40 ℃ more than 30 J. After tempering at 450 ℃, a large number of ε-Cu particles precipitated in C-Mn-Mo-Nb-Cu-B steel produced by CR+DQ+T process lead to a significant increase in yield strength. And after tempering at 500 to 600 ℃, the yield strength of the steel is further improved to 1030 MPa because of precipitates, such as nitride or carbide of niobium, carbide of molybedenum and vanadium. When the tempering temperature is increased above 620 ℃, the yield strength is still higher than 1000 MPa and elongation is above 20% and impact energy at -40 ℃ is more than 35 J. After tempering at above 500 ℃, the toughness of the steel treated by TMCP+QT process is superior to that of steel by CR+DQ+T process.     

回火温度对Cu-Cr-Ti马氏体耐磨钢组织及强韧性的影响

摘要：矿山机械用耐磨钢构件服役环境恶劣而常常出现磨损失效,研究适用于复杂工况下的高耐磨钢成分、工艺与组织性能的关系,有利于提高耐磨构件的服役寿命并降低经济损失。利用SEM、TEM、洛氏硬度计、万能拉伸试验机及冲击试验机等,研究了160～400℃不同回火温度下Cu-Cr-Ti马氏体耐磨钢的组织形貌、强度硬度及-20℃冲击韧性的变化。结果表明,试验钢淬火态组织主要为板条马氏体,当回火温度为160℃时,马氏体板条依然清晰,但随回火温度升高到400℃,马氏体板条界渐渐消失,基体中出现大量片状或粒状渗碳体。EDS分析发现样品钢基体中含有纳米级Ti、Nb的碳氮化物。随回火温度升高,基体组织演变导致强化机制发生变化,回火温度为300℃,综合力学性能最佳,其抗拉强度为1500MPa,屈服强度1100MPa,伸长率为15.5%。随回火温度升高,-20℃冲击韧性由60J/cm2逐渐降低到36.3J/cm2。     

回火温度对COST-FB2转子钢析出相与力学性能的影响

 为了调整COST-FB2转子钢的强韧性,采用OM、SEM和TEM等手段研究了回火温度对COST-FB2转子钢的析出相类型与力学性能的影响。结果表明,随着回火温度由350 ℃升高到750 ℃,试验钢的强度、硬度不断下降,塑性和冲击功上升;试验钢350 ℃和570 ℃回火后的高强低韧性可通过再次在700 ℃回火改善。淬火后COST-FB2转子钢中的残余奥氏体,可通过在570 ℃回火消除;在350 ℃和570 ℃回火后马氏体板条内部有大量针状的M₃C,700 ℃回火后的显微组织中M₃C消失,M₂₃C₆在原奥氏体晶界和马氏体板条界上析出,750 ℃回火后晶界上的M₂₃C₆有聚集粗化的现象,部分马氏体板条存在回复现象。     

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.