深冷处理对铜合金组织和性能的影响

对铅黄酮作了深冷处理,并进行力学性能和金相组织分析。结果表明,深冷处理能改善铅黄酮的组织和性能。     

深冷处理对Al-Si合金组织和力学性能的影响

在液氮温度（-196℃）对Al-Si合金作了深冷处理，处理时间分别为72h、120h，并进行了力学性能试验和金相组织分析。试验结果表明，深冷处理显著提高了合金的强度和硬度，经适当时间的深冷处理，强度、硬度及伸长率三者能同时提高。初步的研究认为，深冷处理改善铝合金性能的机理主要是处理后合金中产生大量相互缠绕的位错和析出弥散强化相。     

深冷处理对超低温轧制2524铝合金板材组织及性能的影响

采用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电镜(SEM)和电子万能试验机等研究了深冷处理对超低温轧制2524铝合金轧制板材显微组织和力学性能的影响。结果表明,深冷处理后2524铝合金中第二相主要沿晶界分布,数量增多,主要为S-Al₂CuMg相和θ-Al₂Cu相。与轧制板材相比,深冷处理后板材的织构极密度均有提升,呈现先增加后降低的趋势,在深冷处理9 h时达到了峰值。经深冷处理6 h后板材的抗拉强度和伸长率分别为490 MPa和6.35%。同时该深冷条件下,试样的断裂模式主要表现为韧性断裂。     

深冷处理对AZ31镁合金焊接接头组织与性能的影响

针对镁合金焊接接头的软化问题,采用不同深冷时间对AZ31镁合金MIG焊接接头进行了深冷处理,并测试与分析了不同深冷时间下焊接接头的力学性能和显微组织。结果表明,深冷处理可显著强化AZ31镁合金焊接接头,其中经过(-196℃,12 h)深冷处理后的焊接接头,硬度提高了8.3%,抗拉强度与伸长率分别提高了15.43%和10.16%;随着深冷时间的延长,焊接接头的组织进一步细化,并有第二相在基体上不断析出,且呈弥散分布。     

深冷处理时间对A319合金显微组织和力学性能的影响

采用力学性能测试仪、光学显微镜、扫描电镜研究了深冷处理时间对A319合金显微组织和力学性能影响。结果表明,随着深冷处理时间的延长,A319合金室温拉伸强度和伸长率先增大后降低,在24 h时达到最大值,比常规热处理试样力学性能分别提高6%,42%。这主要是因为深冷处理对合金有预时效作用,随着深冷时间的延长,富铁相钝化,且大部分成细小的颗粒状,均匀分布在共晶区,大大减小了对材料性能的危害,有利于力学性能的改善。     

深冷处理对5083Al-Mg合金组织和性能的影响

试验研究了深冷处理时间对5083Al-Mg合金力学性能和硬度的影响。研究表明,5083Al-Mg合金的抗拉强度在0～72 h范围,随着深冷处理时间的增加而增大;深冷处理时间过长,对于进一步改善合金的抗拉强度反而不利。综合分析试验结果揭示,深冷处理改善合金力学性能的较佳处理时间为12～24 h。合金提高强度和硬度的机理是,在深冷处理过程中,合金基体组织发生晶格畸变、位错增殖和缠绕,同时伴随Al₃Mg₂相弥散析出。     

深冷处理对镍钴铜合金组织和性能的影响

对Ni-Co-Cu合金进行固溶、时效及深冷处理试验,研究了深冷处理对其组织和性能的影响。试验结果表明,经930 ℃×2 h固溶+550 ℃×2 h时效后+深冷2 h后合金的硬度明显比930 ℃×2 h固溶+550 ℃×2 h时效后合金的硬度要高,可达102.1 HBS。该合金经热处理后析出的主要强化相为k相[ (CoNi)Cu₄],经深冷处理后析出的强化相更加细小、均匀地分布在基体上。     

深冷处理对废铝易拉罐合金组织和力学性能的影响

在液氮温度下对废铝易拉罐合金作了48 h的深冷处理,并进行了金相组织分析和力学性能测试。结果表明,深冷处理显著提高了合金的力学性能,抗拉强度和伸长率分别提高了10.7%和36.2%。     

深冷处理对2024铝合金挤压棒材组织及性能的影响

试验研究深冷处理对2024铝合金挤压棒材综合性能的影响。包括深冷处理对其显微组织、力学性能、疲劳性能、抗腐蚀性及残余应力等的影响。结果表明,2024铝合金挤压棒材采用495℃1 h固溶、淬火+(-196℃30 min)深冷处理+185℃7 h时效处理后,其综合性能最佳,具有高强度的同时,显微组织、疲劳性能、抗腐蚀性、降低残余应力等均有很大改善。     

深冷处理对304LN不锈钢板焊接接头组织和力学性能的影响

304LN不锈钢板焊接件在焊接接头处取样分别以2℃/min和5℃/min速率进行深冷处理,对其深冷前后显微组织和力学性能变化进行分析。试验结果表明:深冷处理使得材料内部奥氏体向马氏体转化,并伴有碳化物和氮化物的析出。以5℃/min速率进行深冷处理,相较于2℃/min深冷速率析出物数量更多且分布更加均匀;深冷处理使得304LN不锈钢板焊接接头抗拉强度和冲击韧性得到提高。与未处理试样相比,经历3次2℃/min深冷处理试样抗拉强度和冲击韧性分别提高了1. 24%和16%,经历3次5℃/min深冷处理试样抗拉强度和冲击韧性分别提高了4. 77%和23%。综合考虑两种深冷工艺,以5℃/min深冷处理能获得最佳的力学性能,该工艺可作为304LN不锈钢板焊接接头增强增韧处理方法。     

钼对低碳微合金钢组织和性能的影响

研究了低碳微合金钢中Mo元素对形变奥氏体在连续冷却后组织和性能的影响。得出在此系列钢中，随Mo含量增加，针状铁素体量随之增加，同时钢中出现贝氏体束和M-A组织。屈服强度、抗拉强度随Mo含量的增加而提高，且抗拉强度的提高幅度高于屈服强度，屈强比随Mo的加入而降低，且随M～A组织增多，钢的冲击韧性损失加大。     

Low-temperature martensitic transformation in tool steels in relation to their deep cryogenic treatment

The low-temperature martensitic transformation in steel X153CrMoV12 containing (mass%) 1.55C, 11.90Cr, 0.70V, 0.86Mo is studied using dilatometry, Mössbauer spectroscopy, X-ray diffraction, mechanical spectroscopy and transmission electron microscopy. Some additional measurements were carried out on steel X220CrMoV13-4. It is shown that, in contrast to the widely known absence of martensitic transformation during deep cryogenic treatment, this transformation occurs with isothermal kinetics within the temperature range of ?100 down to ?170 °C with its largest intensity near ?150 °C. No transformation is observed at ?196 °C. The remarkable features of the isothermal martensitic transformation are: (i) the plastic deformation, which is explained by the absence of ageing of martensite at low temperatures; and (ii) the abnormally low tetragonality of martensite. In contrast to existing interpretations, the abnormally low c/a ratio is interpreted in terms of the capture of immobile carbon atoms by gliding dislocations during plastic deformation at low temperatures. A recommendation is proposed for optimizing the deep cryogenic treatment of tool steels.     

Evaluation of factors influencing deep cryogenic treatment that affect the properties of tool steels

Deep cryogenic treatment (DCT) of tool steels is used as an additive process to conventional heat treatment and usually involves cooling the material to liquid nitrogen temperature (−196 °C). This kind of treatment has been reported to improve the wear resistance of tools. In this study, the Taguchi method was used to identify the main factors of DCT that influence the mechanical properties and the wear resistance of the powder metallurgically produced cold-work tool steel X153CrVMo12 (AISI D2). Factors investigated were the austenitizing temperature, cooling rate, holding time, heating rate, and tempering temperature. In order to study the significance of these factors and the effect of possible two-factor interactions L₂₇(3¹³), an orthogonal array (OA) was applied to conduct several heat treatments, including a single DCT cycle directly after quenching prior to tempering. The results show that the most significant factors influencing the properties of tool steels are the austenitizing and tempering temperatures. In contrast, the parameters of deep cryogenic treatment exhibit a lower level of significance. Further investigations identified a nearly constant wear rate for holding times of up to 24 h. The wear rate reaches a minimum for a longer holding time of 36 h and increases again with further holding.     

紫铜的深冷处理研究

采用显微硬度、拉伸试验、XRD、光学显微镜等手段,对紫铜深冷处理前后的力学性能和组织进行了对比分析.结果表明,深冷处理24h后,紫铜的显微硬度和强度都得到了提高;深冷处理会引起衍射峰的强弱变化,出现择优趋向;同时衍射峰发生了宽化,可能是晶粒细化引起的.     

循环冷处理对低碳马氏体不锈轴承钢组织和性能的影响

研究了循环冷处理对一种Fe-Cr-Co-Ni-Mo系低碳马氏体不锈轴承钢组织和性能的影响。结果表明,随着冷处理和高温回火次数的增加,马氏体板条细化,钢的硬度升高,相应的冲击吸收能量降低。冷处理促使钢中残留奥氏体量减少,最终约有2%的薄膜状残留奥氏体分布于马氏体板条间。     

深冷处理对5A06铝合金焊接接头组织与性能的影响

针对铝合金在焊接后出现的接头软化问题,采用深冷处理工艺使其强化.采用不同的深冷处理工艺参数对5A06铝合金M1G焊接接头进行了深冷处理,并测试与分析了深冷处理与未深冷处理的焊接接头的力学性能和显微组织.试验结果表明,深冷处理可显著强化焊接接头;经深冷处理后焊接接头焊缝区晶粒得到细化,第二相在基体上析出,呈弥散分布,组织...     

Classic contributions: cryogenic treatment Deep cryogenic treatment of tool steels: a review

Abstract

As opposed to conventional sub-zero treatment to transform retained austenite, deep cryogenic treatment at liquid nitrogen temperatures has been claimed to enhance the wear resistance of tool steels by additional hitherto ill defined phenomena. In summarising current knowledge at the time of writing (1996), this review and the following paper sought to clarify the underlying mechanisms.     

Effect of boron addition on the microstructures and mechanical properties of thermomechanically processed and tempered low carbon bainitic steels

Thermomechanical process and tempering heat treatment were employed to produce the experimental steel plates. The effect of boron addition on the microstructure and mechanical properties of low carbon bainitic steels was studied in this paper. Microstructure observation and crystallographic features were conducted by using optical microscopy, SEM, TEM and electron back scattering diffraction (EBSD) analysis. The results showed that under the same rolling processes and heat treatment conditions, a substantia...     

Plastic deformation of low carbon steels

Abstract

The plastic deformation of two steels was studied by means of axisymmetric compression tests carried out in a computer driven servohydraulic machine. The tests were conducted within the temperature range of 700–1100°C for steels that have similar carbon contents, but differed in other alloying elements. Little difference in strength between the steels was found when deformation took place in the austenite phase field, but the strength of the material varied as soon as ferrite was present. The critical temperatures were evaluated by means of thermal analyses, which were conducted by inserting a thermocouple within samples of the two steels; these temperatures were found to be close to those predicted by empirical equations.