热处理对Fe-6.5wt%Si合金冷轧薄板组织及磁性能的影响

Fe-6.5wt%Si合金具有优异的软磁性能,但由于有序相的出现,室温塑性低,很难用传统的轧制方法制备薄板。研究了一种特殊的轧制方法和相应的热处理工艺,冷轧出了厚度为0.03～0.05mm的该合金薄板。在制备过程中,通过观察热处理前后材料显微组织,硬度和结构的变化,研究热处理对材料塑性的影响;通过观察冷轧薄板热处理前后磁性能的变化,研究热处理对磁性能的影响。研究表明,通过采取不同的热处理手段,可以抑制部分有序相的生成,提高材料塑性或者生成有序相,提高材料磁性能。     

温轧温度对高硅钢力学性能及织构的影响

Fe-6.5wt%Si合金是一种具有高磁导率,低矫顽力和低铁损等优异软磁性能的合金。但是,室温脆性和低的热加工性能限制了其在工业领域的应用。人们难以用普通轧制的方法得到该合金的薄板。在实验室条件下利用热轧、温轧方法,结合相关的热处理手段,得到该合金0.3 mm温轧薄板。利用光学显微镜、显微硬度仪、扫描电镜研究不同温轧温度对该薄板组织结构、力学性能的影响。     

热处理工艺对高硅钢复合板软化行为的影响

采用显微硬度计、光学显微镜、X射线衍射仪等手段,对经复合方法及热轧工艺制备的高硅钢薄板(覆层为Fe-3%Si,芯层为Fe-10%Si)进行不同工艺的热处理,研究其软化行为,并通过温轧实验进行验证。结果表明:经850℃保温1 h,采用盐水冷的热处理工艺可使得复合板综合硬度最低;晶粒大小不是高硅钢复合板软化的主要原因;B2相的出现,使得材料的有序度下降,从而造成复合板芯层硬度的降低,同时急冷还可导致材料的芯层出现B20相。经热处理工艺后在720℃下温轧可获得表面质量良好、厚度为0.45 mm的薄板,高温扩散后整体Si元素含量为6.2%。     

退火对LA141镁-锂合金板材显微组织与力学性能的影响

采用真空感应熔炼方法制备了LA141(Mg-14Li-1Al)超轻镁-锂合金,并通过挤压和轧制变形制备了0.8 mm厚的板材,轧制压下率达到90%以上。对轧制板材进行了两种工艺退火,通过OM、XRD、SEM等手段观察热处理前后轧板的显微组织,通过拉伸试验和硬度测试测定退火前后的力学性能。结果表明,温轧的方法有利于制备出宽幅薄板,且成品率较高;温轧LA141镁-锂合金薄板材具有较高的塑性;退火后,细晶强化作用和析出强化作用使合金的强度增加,但伸长率有所下降;225℃2 h退火后,合金具有较好的综合性能。     

固溶和时效温度对IMI834钛合金板材组织和性能的影响

研究了不同固溶时效温度对IMI834合金显微组织和力学性能的影响。结果表明:IMI834合金板材经低温热处理的组织和轧态没有明显差别,室温强度也与轧态基本保持不变;合金在α+β两相区热处理后得到双态组织,随着固溶温度的升高,初生α相含量减少,室温强度略有增加,塑性的变化规律与强度相反,初生α相含量的减少对板材的室温强度没有明显的影响。随着时效温度的提高,板材的室温强度降低,塑性有所降低。板材的600 ℃高温力学性能变化规律与室温相似,但断面收缩率较室温好。本试验得到的较优的热处理制度为1035 ℃×1 h, AC+(700~750) ℃×4 h, AC。     

热处理对选区激光熔化钴铬合金组织与性能的影响

为明确热处理对选区激光熔化(SLM)钴铬合金成形件组织、性能的影响,利用OM、SEM、XRD、EBSD、EPMA、力学性能和电化学测试研究了激光功率为290 W、扫描速度为950 mm/s下SLM成形的钴铬合金在1150℃保温6 h的热处理前后的微观组织和性能变化。结果表明,钴铬合金成形件经过热处理后,典型熔池形貌消失,可在晶界和晶内观察到明显析出的碳化物,晶粒由粗大的柱状晶转变为细小的等轴晶,耐腐蚀性能降低,硬度变化较小,而伸长率提高约30%。通过热处理可以获得均匀的微观组织,提高γ相的体积分数,提升成形件的塑性,但会降低成形件电化学腐蚀性能。     

用EB-PVD技术制备Ni-Co-Cr基高温合金的组织和力学性能

采用电子束物理气相沉积（EB-PVD）技术制备出厚度为0．3mm的Ni-Co-Cr基高温合金薄板，并用X射线衍射仪、光学显微镜、扫描电镜和拉伸设备研究了该合金热处理前后的显微组织及力学性能。结果表明，制备态合金为微晶结构，缺陷相对较多；热处理后晶粒迅速长大，缺陷密度大幅下降，并在晶粒内部形成了主要的沉淀强化相γ’相。与制备态合金相比，热处理后合金的力学性能得到明显改善，说明EB-PVD技术可以为制备性能优良的高温合金薄板提供一条新途径。     

热处理对Ti6242S合金组织和性能的影响

研究了不同热处理制度对Ti6242S合金显微组织和力学性能的影响。结果表明,Ti6242S合金在α+β两相区热处理后得到双态组织。随着固溶温度的升高,初生α相含量减少,强度增加,塑性降低;随着时效温度的提高,析出的次生α相的数量增多,强度先增加后降低,塑性变化不明显。随着冷却速度的提高,合金强度显著升高,塑性降低。本试验得到的最佳热处理制度为965℃×1 h,空冷+595℃×8 h,空冷,可获得良好的组织和性能。     

退火对冷轧LZ91镁锂合金组织与冲压性能的影响

通过真空感应熔炼、挤压和室温轧制制备了0.9 mm厚的LZ91镁锂合金薄板,采用金相观察、维氏硬度及杯突试验研究了不同工艺退火后合金的组织及冲压性能。结果表明:冷轧LZ91合金由α相和β相组成,显微组织为纤维状,冷轧纤维呈波浪状沿轧向延伸。退火后,合金发生再结晶,α相由纤维状转变为竹节状,进一步转变为岛状,尺寸逐渐增大,β相晶粒转变为等轴状且尺寸逐渐变大;随着退火温度的升高和保温时间的延长,合金的硬度逐渐下降,杯突试验IE值逐渐增大。合金板经200℃×4 h退火后,具有较优的综合性能,此时合金IE值为7.82 mm,维氏硬度为67 HV0.025。     

大规格TC2钛合金包套叠轧薄板制备技术及组织性能研究

采用包套叠轧工艺生产出了宽幅大规格TC2钛合金薄板,研究了包套叠轧工艺对TC2钛合金薄板组织和力学性能的影响。结果表明:采用包覆叠轧在两相区轧制的大规格TC2合金薄板具有细小、均匀的等轴组织。采用交叉轧制的包覆叠轧可获得均匀的组织及较好的室温强度和塑性匹配。它的纵、横向性能均匀一致,有利于后续板材加工成形。     

Enhanced Strength in Cu-Ag-Zr Alloy by Combination of Cold Working and Aging

In this investigation, the effect of different degree of cold rolling and post-aging treatment on the microstructure and mechanical properties of a Cu-3wt.%Ag-0.5wt.%Zr alloy was studied by means of hardness measurement, tensile tests, optical and electron microscopy. The alloy was subjected to cold rolling up to 80% followed by aging in the temperature range of 400-500 °C. The yield strength, ultimate tensile strength and hardness were found to increase as degree of cold rolling increased, but at the expense of ductility. Aging of cold rolled samples in the studied temperature range has resulted in different combinations of strength and ductility. However, aging of cold rolled samples at 400 °C for 1 h has resulted in a combination of high strength and moderate ductility. A yield strength and ultimate tensile strength of 511 and 560 MPa, respectively with a ductility of 12% were achieved for 80% cold rolled and aged (400 °C for 1 h) sample. The high strength achieved after 80% cold rolling and aging is mainly attributed to precipitation of fine silver precipitates.     

Effects of magnesium and copper additions on tensile properties of Al-Si-Cr die casting alloy under as-cast and T5 conditions

Aluminum high pressure die casting(HPDC) technology has evolved in the past decades, enabling stronger and larger one-piece casting with significant part consolidation. It also offers a higher design freedom for more mass-efficient thin-walled body structures. For body structures that require excellent ductility and fracture toughness to be joined with steel sheet via self-piercing riveting(for instance, shock towers and hinge pillars, etc.),a costly T7 heat treatment comprising a solution heat ...     

Processing and properties of Nb- Ti- base alloys

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep test at 650 °C and 172 MPa was conducted on the base alloy, which contained 40Nb-40Ti-10Al-10Cr. A second alloy was modified with 0.11 at.% C and 0.07 at.% Y. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1100 °C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400,600,700,800,900, and 1000 °C and for the modified alloy at room temperature, 400,600,700, and 800 °C. Oxidation tests on the base alloy and modified alloy, as measured by weight change, were carried out at 600,700,800, and 900 °C. Both the base alloy and the modified alloy were extremely ductile and were cold rolled to the final sheet thickness of 0.8 mm without an intermediate anneal. The modified alloy exhibited some edge cracking during cold rolling. Both alloys recrystallized at the end of a 0.5-h annealing treatment. The alloys exhibited moderate strength and oxi-dation resistance below 600 °C, similar to the results of alloys reported in the literature. The addition of carbon produced almost no change in either the yield strength or ductility as measured by total elonga-tion. A small increase in the ultimate tensile strength and a corresponding decrease in the reduction of area below 600 °C were observed. Carbon addition also served to marginally refine the grain size after annealing. The results of this study and those of similar alloys reported in the literature suggest that 40Nb-40Ti-10Al-10Cr forms a good base alloy suitable for alloying for improvement in its oxidation and high-temperature strength properties.     

AZ31B镁合金热拉伸流变应力研究

针对不同加工方法制备的AZ31B镁合金薄板,利用热拉伸试验机和金相显微镜对其在不同温度和变形速率下的流变应力进行了实验研究。结果表明,变形温度和变形速率对热拉伸时镁合金的流变应力有显著影响,峰值流变应力随应变速率的降低和变形温度的升高而降低。峰值流变应力随板材的厚度增加而发生变化,低温时厚度效应较为明显。退火处理对冷轧板的峰值流变应力影响较小,冷轧板可直接用于热加工成形。峰值流变应力变化规律:挤压板>热轧板>冷轧板。     

固溶处理对Al-8.8Zn-2.0Mg-2.1Cu-0.1Zr-0.1Ce合金组织性能的影响

采用拉伸性能和导电率测试、光学显微镜(OM)、扫描电镜(SEM)、差热分析(DSC)、透射电镜(TEM)研究了固溶温度和时间对Al-8.8Zn-2.0Mg-2.1Cu-0.1Zr-0.1Ce合金板材微观组织、拉伸性能及断口形貌的影响。结果表明,试验合金适宜的固溶工艺为470 ℃×60 min,使冷轧态金属间化合物充分固溶。在此工艺下合金时效后的抗拉强度、屈服强度(以R_p0.2计)以及伸长率分别为646 MPa、581 MPa和14.5%。TEM观察发现合金板材固溶时效后晶内强化相η′仅为2~5 nm,并且晶界析出相η呈现断续分布。此外,合金拉伸断面韧窝中大量弥散分布的AlCuCeZn粒子有利于合金塑性的明显提升。     

AZ31B镁合金轧制板材室温动态拉伸的SEM观察

利用动态拉伸台和扫描电镜(SEM)对AZ31B镁合金轧制板材进行了动态拉伸的微观形貌观察。试验证明,材料宏观织构和显微组织都会对镁合金轧制板材的室温拉伸性能产生影响;在轧制镁合金拉伸变形时滑移和孪生同时存在;裂纹的产生和扩展具有明显的方向性。轧制组织中大量的变形孪晶与应力方向的位向关系,是轧向和横向上裂纹产生及扩展机制产生较大差异的主要原因。     

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

A novel method of pulsed magnetic field(PMF) treatment was developed to eliminate the residual stress of rolled magnesium alloy AZ31 sheet in this study.The eff ect of PMF on residual stress of rolled AZ31 sheet was investigated and its mechanism was analyzed.The experimental results revealed that the pulse frequency had a significant impact on residual stress.After 10.0 Hz PMF treatment,the average and maximum reduction rates of residual stress along the rolled direction were 26.6% and 30.3%,respectively.It was found that the dislocation density and parallel dislocation in grains of the rolled sheet increased after it was treated by the pulsed magnetic field.The simulation results showed that the Lorentz force generated by the pulsed magnetic field can lead to basal slip,thereby resulting in local plastic deformation.Besides,the Joule heat produced during the PMF treatment was conducive to the elimination of residual stress.     

包裹管道用3A21料冷轧工艺改进

针对包裹管道用3A21合金板材冷轧时表面油痕废品和表面花脸缺陷，提出了采用中间退火代替成品退火及控制中间退火后的冷轧变形量的改进工艺，同时调整3A21合金Mn的含量控制再结晶晶粒度。通过跟踪试验，改进工艺大大降低了成品表面油痕废品率，减少了板材表面花脸缺陷，保证了力学性能。     

微量铬强化B10合金形变热处理后的组织及性能

利用真空感应熔炼-铸造工艺制备了微量铬强化的B10合金(即Cu-10Ni-0.3Cr(mass%)合金),并对铸态合金进行固溶、冷变形及退火处理,采用光学显微镜、拉伸测试和四线制测量法等研究了不同处理状态下Cu-10Ni-0.3Cr合金的显微组织、力学性能和电导率。结果表明,铸态Cu-10Ni-0.3Cr合金晶粒为等轴状,晶粒中均匀分布着黑色颗粒状析出相;再结晶退火后合金的组织均匀细小,晶粒内有明显的退火孪晶。铸态合金的导电性最好,电导率为17.15%IACS,900℃固溶2 h后合金的导电性最差,电导率为12.30%IACS。冷轧态(50%变形量)合金的强度、硬度最高,分别为340 MPa、112 HB,延塑性最差,伸长率只有8%;再结晶退火态合金综合力学性能最好;随着退火温度升高,冷轧态合金形变组织逐渐消失,且退火温度愈高,形变组织消失得愈明显,同时晶粒在退火过程中发生长大,最终导致合金强度、硬度降低,塑性增加。     

薄片状TiNi形状记忆合金的激光对接焊

采用低功率脉冲激光对厚度为0.2mm的TiNi形状记忆合金进行了对接焊,研究了接头的抗拉强度、断裂应变、相变过程和形状记忆效应.试验发现,低功率脉冲激光能够实现薄片状TiNi合金的良好焊接.冷轧态TiNi合金焊后接头的强度达到母材的97%,断裂应变为母材的95%,对接头进行焊后退火处理其强度有所提高,高于冷轧态母材、达到退火态母材的63.6%,断裂应变为退火态母材的82.5%.冷轧态TiNi合金焊接接头经焊后退火处理,其相变过程和退火态母材接近,形状记忆效应基本和退火态母材相同.