两相区热处理对ZG14Ni3CrMoV铸钢低温韧性的影响

对比了淬火+回火(QT),淬火+两相区淬火+回火(QLT)两种热处理工艺对ZG14Ni3CrMoV铸钢组织和性能的影响.结果表明,QLT工艺在保证铸钢板厚四分之一强度满足指标要求、塑性良好的情况下,大幅度提高了ZG14Ni3CrMoV铸钢的低温韧性,-80℃冲击吸收功提高到171 J,NDT温度降低至-95℃;晶粒细化和双相组织是两相区二次淬火提高低温韧性的主要原因.     

两相区热处理对ZG14Ni3CrMoV铸钢低温韧性的影响

对比了淬火+回火(QT),淬火+两相区淬火+回火(QLT)两种热处理工艺对ZG14Ni3CrMoV铸钢组织和性能的影响。结果表明,QLT工艺在保证铸钢板厚四分之一处强度满足指标要求、塑性良好的情况下,大幅度提高了ZG14Ni3CrMoV铸钢的低温韧性,-80℃冲击吸收功提高到171J,NDT温度降低至-95℃;晶粒细化和双相组织是两相区二次淬火提高低温韧性的主要原因。     

两相区保温时间对QLT处理9Ni钢组织及性能的影响

将淬火态9Ni钢加热至670℃保温不同时间后水冷并回火.然后采用XRD法测定了实验钢中的逆转变奥氏体含量,进而分析了两相区保温时间对最终组织及性能的影响.结果表明:两相区保温时间为5 min时,其淬火组织特征与QT工艺较为接近;保温时间在10～30 min时,获得的组织与QT淬火后的组织产生明显的差异,组织中的大角度晶界显著增加,促进了回火过程中逆转变奥氏体的形成及钢低温韧性的改善;保温超过30 min后两相区淬火的特征逐渐减弱,钢的组织和性能再次趋近于QT处理,但当两相区保温时间更长时钢的低温韧性略有增加,这可能是由于钢中Ni元素的分布更加不均匀,促进了富Ni区形成更加稳定的逆转变奥氏体.     

两相区淬火对7Ni钢微观组织和力学性能的影响

利用X射线衍射仪、扫描电镜和热膨胀仪,研究两相区淬火温度和保温时间对7Ni钢显微组织及力学性能的影响。基于热膨胀曲线,定量地测量了7Ni钢在淬火+两相区淬火+回火(QLT)工艺各阶段的逆转奥氏体生成量及转变速率,揭示逆转奥氏体的转变过程。结果表明:逆转奥氏体在QLT工艺中的转变依次经历了淬火保温、淬火冷却、回火保温、回火冷却四个过程。适当升高两相区淬火温度和延长保温时间,有利于回火过程中逆转奥氏体的转变,并促进其均匀分布,从而使7Ni钢强度降低,塑韧性增强。两相区淬火工艺为660℃保温30min时,7Ni钢综合力学性能达到最佳,并完全满足标准ASTM A553规定的9Ni钢的力学性能要求。     

热处理工艺对34CrNiMo6钢性能的影响研究

目的 提高34CrNiMo6钢构件抗拉强度、屈服强度以及伸长率的匹配程度,进而提高合金的冲击韧性和疲劳性能。方法 通过热处理试验,研究不同工艺对材料组织和性能的影响。采用预先热处理（正火+高温回火）→调质热处理（淬火+回火）的工艺,研究不同淬火和回火温度对试样组织及力学性能的影响。结果 随着淬火温度的升高,试样的强度有所增加,伸长率差别不大,在淬火温度为900 ℃时冲击韧性有所下降。随着回火温度的升高,强度明显降低,但伸长率逐渐升高,冲击韧性则稍有提升。结论 通过试验确定了材料的热处理工艺：850 ℃淬火+580 ℃回火。在该调质工艺下,材料的强度和塑性得到了合理的匹配。     

Cu对9Ni钢强度和低温韧性的影响

研究了Cu含量(质量分数)对9Ni钢强度和低温韧性的影响,并结合显微组织观察和精细结构分析了含铜9Ni钢的强韧化机理.结果表明,经过淬火+两相区淬火+回火(QLT)处理,Cu含量由0提高到1.5%,9Ni钢的室温屈服强度和抗拉强度分别提高约150和105 MPa;随着Cu含量的提高-196℃低温冲击功呈现先增加后降低的趋势,Cu含量为1.0%时达到最高值157 J,而所有含铜9Ni钢的冲击功均保持在较高的水平。随着Cu含量的增加,钢中二次回火马氏体增加而铁素体减少;颗粒或短杆棒状Cu析出物在基体上析出,组织强化与析出强化共同使钢的强度提高。同时,Cu的加入提高了二次回火马氏体板条边界上的逆转奥氏体含量,并富集于逆转奥氏体中提高其稳定性,从而提高了钢的低温韧性。     

空调螺钉热处理工艺的特点

空调螺钉采用在真空条件下高温淬火＋低温回火工艺（淬火温度为1050℃,回火温度为200℃）,淬火介质为高压压缩空气。对热处理后的螺钉进行显微组织观察和分析,并结合该螺钉的材质分析结果,说明该螺钉采用的热处理工艺能使其获得平衡态组织,达到了产品塑性、韧性和耐腐蚀性的最佳配合要求。     

国产5Ni钢的显微组织

本文分析了_5Ni 钢淬火、低温回火、高温回火等不同热处理状态的显微组织。_5Ni 钢中存在的逆转奥氏体,对提高钢的韧性可能起了重要作用。     

MICROSTRUCTURE OF 5Ni STEEL

本文分析了_5Ni 钢淬火、低温回火、高温回火等不同热处理状态的显微组织。_5Ni 钢中存在的逆转奥氏体,对提高钢的韧性可能起了重要作用。     

XCQ16-1车桥用钢调质热处理工艺的研究

为了提高整体式车桥用钢的综合力学性能,对XCQ16-1钢进行了调质热处理工艺研究.通过材料单向拉伸、冲击和硬度等试验,研究了不同回火温度、回火保温时间、淬火温度和淬火保温时间对XCQ16-1钢力学性能的影响规律,制定了试验条件下的调质热处理工艺,并分析了不同工艺参数对材料组织的影响规律.试验结果表明:回火工艺对XCQ16-1钢组织和力学性能的影响比较大,随回火温度的升高和回火保温时间的延长,材料的强度性能下降,塑性和韧性指标上升.经860℃保温30min淬火+470℃保温90min回火调质处理后,该材料可获得良好的综合性能.     

热处理工艺对连铸10CrNi3MoV钢性能的影响

针对高温热成型及正常调质处理后连铸10CrNi3MoV钢性能恶化这一问题,研究了循环/亚温淬火热处理工艺,进行了力学性能测试、显微组织观察及晶粒度评定.结果表明,采用亚温淬火( 835℃×2h+ 820℃×2h)+高温回火(630℃×3h)热处理工艺,可有效细化连铸10CrNi3MoV钢的晶粒,显著改善其低温韧性,使其...     

热处理对C12A耐热钢的组织与性能影响

通过对铸造C12A耐热钢进行热处理,观察其微观组织,测定其力学性能。试验结果表明：正（淬）火组织为板条马氏体＋部分针状马氏体＋少量残余奥氏体,其硬度比较高,塑性和韧性不是很好;正（淬）火＋回火组织为回火马氏体,其硬度不是很高,塑性和韧性比较好,具有良好的综合性能;退火组织为铁素体,其硬度低,塑性和韧性高;通过正火＋回火,研究回火温度对其微观组织和力学性能的影响。试验结果表明：回火温度对C12A钢的组织和性能有较大影响,其硬度随回火温度的升高呈先降后升趋势。     

Enhancement of the mechanical properties of EN52CrMoV4 spring steel by deep cryogenic treatment

The effect of the deep cryogenic treatment on the micro-structure and mechanical properties (tensile strength, toughness, residual stress and fatigue strength) of the medium carbon spring steel, which is subjected to different heat treatment steps, is investigated. Deep cryogenic treatment causes spring steel to keep compressive residual stress more efficiently due to an increase in the density of the crystalline defects, retardation in the stress relief after the phase transformations and nano-cluster carbide formations. If deep cryogenic treatment is applied before the tempering then the homogeneously distributed fine carbides form after the tempering and the grains remain relatively fine. The microstructure with homogeneously distributed fine carbides and fine grains cause spring steels to have simultaneously enhanced tensile strength, ductility and fatigue strength. If deep cryogenic treatment is applied after the conventional heat treatment (quenching+tempering), however, the coarse carbides form in the micro-structure and the improvement in the mechanical properties of the spring steel is limited.     

热处理工艺对压裂泵阀体用钢4330MOD组织及性能的影响

为提高压裂泵阀体的强度和韧性,研究了不同热处理工艺对改进型4330钢组织及力学性能的影响。结果表明:4330MOD钢通过添加微合金元素及调质工艺优化能够提高强度和韧性。微合金元素Nb、V,正火+调质工艺能够降低晶粒尺寸,提高强韧性。4330MOD钢在550℃～700℃回火时,组织为回火索氏体组织,随回火温度的升高强度降低,韧性先升高后降低,在600℃～650℃回火强韧性匹配较好。4330MOD钢通过微合金元素添加及热处理工艺优化使晶粒尺寸及板条块宽度细小,大角度晶界比例高,从而提高了钢的强韧性。      

Effect of direct quenching on the microstructure and mechanical properties of the lean-chemistry HSLA-100 steel plates

The influence of direct quenching on structure-property behavior of lean chemistry HSLA-100 steels was studied. Two laboratory heats, one containing Cu and Nb (C:0.052, Mn:0.99, Cu:1.08, Nb:0.043, Cr:0.57, Ni:1.76, Mo:0.55 pct) and the other containing Cu, Nb and B (C:0.04, Mn:1.02, Cu:1.06, Nb:0.036, Cr:0.87, Ni:1.32, Mo:0.41, B:0.002 percent) were hot-rolled into 25 and 12.5 mm thick plates by varying finish-rolling temperatures. The plates were heat-treated by conventional reheat quenching and tempering (RQT), as well as by direct quenching and tempering (DQT) techniques. In general, direct-quench and tempered plates of Nb-Cu heat exhibited good strength (yield strength ∼ 900 MPa) and low-temperature impact toughness (average: 74 J at −85 °C); the Charpy V-notch impact energies were marginally lower than conventional HSLA-100 steel. In Nb-Cu-B heat, impact toughness at low-temperature was inferior owing to boron segregation at grain boundaries. Transmission electron microscopy (TEM) and scanning auger microprobe (SAM) analysis confirmed existence of borocarbides at grain boundaries in this steel. In general, for both the steels, the mechanical properties of the direct-quench and tempered plates were found to be superior to reheat quench and tempered plates. A detailed transmission electron microscopy study revealed presence of fine Cu and Nb (C, N) precipitates in these steels. It was also observed that smaller martensite inter-lath spacing, finer grains and precipitates in direct-quench and tempered plates compared to the reheat quench and tempered plates resulted in their superior strength and good impact toughness.     

Enhancement of mechanical properties and failure mechanism of electron beam welded 300M ultrahigh strength steel joints

In this study, four post-weld heat treatment (PWHT) schedules were selected to enhance the mechanical properties of electron beam welded 300M ultrahigh strength steel joints. The microstructure, mechanical properties and fractography of specimens under the four post-weld heat treatment (PWHT) conditions were investigated and also compared with the base metal (BM) specimens treated by conventional quenching and tempering (QT). Results of macro and microstructures indicate that all of the four PWHT procedures did not eliminate the coarse columnar dendritic grains in weld metal (WM). Whereas, the morphology of the weld centerline and the boundaries of the columnar dendritic grains in WM of weld joint specimens subjected to the PWHT procedure of normalizing at 970 °C for 1 h followed by conventional quenching and tempering (W-N2QT) are indistinct. The width of martensite lath in WM of W-N2QT is narrower than that of specimens subjected to other PWHT procedures. Experimental results indicate that the ductility and toughness of conventional quenched and tempered joints are very low compared with the BM specimens treated by conventional QT. However, the strength and impact toughness of the W-N2QT specimens are superior to those of the BM specimen treated by conventional QT, and the ductility is only slightly inferior to that of the latter.     

Hardness and toughness investigations of deep cryogenic treated cold work die steel

In consideration of good results about the application of deep cryogenic treatment (DCT) on materials, the effect on the microstructure and properties (hardness, toughness and the content of retained austenite) of a new developed cold work die steel (Cr8Mo2SiV) was examined. The execution of the deep cryogenic treatment in different processes showed a varying effect on materials. It was shown that the hardness of the DCT specimens was higher (+0.5HRC to +2HRC) whereas the toughness was lower when compared with the conventionally treated specimens (quenching and tempering). Following the DCT process retained austenite transformed into martensite, however, not completely.     

Effects of post-weld heat treatment cycles on microstructure and mechanical properties of electric resistance welded pipe welds

Two post-weld heat treatment cycles of one-step normalizing and two-step quenching and tempering have been performed by Gleeble, a thermo-mechanical simulator, to improve the toughness of fine-grained electric resistance welded pipe welds. Comparison was made to API X65 grade steel, which is widely used for pipeline parts. Microstructural evolution was investigated by optical microscopy and transmission electron microscopy. Vickers hardness and Charpy V-notch impact toughness tests were used to evaluate the mechanical properties. While the mechanical properties of one-step normalizing heat treatment satisfied the API specification, the two-step quenching and tempering heat treatments were conditional upon tempering temperature for X65 grade and fine-grained steels. As a result, a one-step normalizing heat treatment was more effective for both steel pipes.     

深冷处理对低碳高合金马氏体轴承钢力学性能及组织的影响

利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高。经深冷处理后实验钢在0~100 h回火过程中的硬度均比未深冷处理实验钢的硬度高。深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,与未经深冷处理的实验钢相比,经深冷处理的实验钢回火后马氏体基体中的含碳量更低,表明实验钢经深冷处理后在回火过程中析出更多的碳化物。透射电镜分析表明,实验钢在回火过程中析出的大量弥散分布的纳米级M2C和M6C型碳化物是实验钢长时间回火后保持高硬度的主要原因。