热处理对SiMn3型贝氏体高强钢组织和性能的影响

利用光学金相、透射电镜（TEM）、扫描电镜（SEM）观察,以及拉伸、硬度、冲击等试验方法,研究了热处理对复合微合金化低碳SiMn3型贝氏体高强钢的组织和力学性能的影响,并对其组织与性能关系进行了讨论.结果表明,该钢在空冷条件下,可获得均一的粒状贝氏体组织,并具有良好的强度与韧性（σ0.2=820 MPa、σb=1118 MPa、αKU=87 J/cm^2）;空冷后经200～300 ℃回火,在贝氏体铁素体（BF）基体上析出了弥散细小的ε碳化物,屈服强度、韧性提高（σ0.2=824～835 MPa、σb=1019～1085 MPa、αKU=136～140 J/cm^2）;在400 ℃以上回火,粒状贝氏体组织开始逐渐分解,BF基体上析出椭球状碳化物,并使强度、韧性降低;500～600 ℃回火,产生回火脆性（σ0.2=787～790 MPa、σb=967～1002 MPa、αKU=72～75 J/cm^2）.空冷后低温回火使该钢获得最佳强韧性组合.     

球化工艺对热轧超高碳钢组织性能的影响

利用离异共析原理，采用不同的热处理工艺球化热轧超高碳钢。组织观察表明：热轧预处理消除了铸态下晶界网状粗大碳化物，并获得颗粒状碳化物与片状珠光体的混合组织。球化热处理时，奥氏体化温度升高、保温时间延长，碳化物颗粒的间距增大，减缓冷却速率增加碳化物的析出。对球化后超高碳钢进行拉伸力学性能试验，850℃球化后的强度很高（σ0.2=688．71MPa，σb=1005．78MPa），屈强比和伸长率分别为0．69、16．7％。拉伸后的断口形貌分析表明，超高碳钢拉伸过程中裂纹易在大颗粒碳化物处萌生、扩展。     

10Cr9Mo1VNb钢高温时效后的性能及组织研究

对10Cr9MolVNb钢进行了高温时效试验和时效后的室温力学性能、显微组织研究。结果表明：10Cr9MolVNb钢在625℃10000h高温时效后室温下σb为650MPa,与时效前的660MPa相比,仅降低了1．5％左右。透射电镜分析表明,基体析出大量弥散M23C6和MC相是10Cr9MolVNb钢具有优良性能的主要原因。     

冷变形和固溶温度对HR3C钢中σ相析出行为的影响

结合HR3C钢制备工艺,综合研究冷变形和固溶处理工艺对其在时效过程中σ相的析出动力学和相关力学性能的影响。结果表明:冷变形和固溶温度均对该钢中σ相的析出有着较大的影响,变形量的增加会促进σ相的时效析出,升高固溶处理温度有助于抑制HR3C钢中σ相的析出行为,但却在一定程度上增大晶粒尺寸。σ相析出量随时间延长先缓慢增加,后快速析出,最后达到稳态值约5.7%(体积分数)。变形量的增加使HR3C钢时效过程中冲击韧性显著降低,而固溶温度的升高虽然增加了固溶态试样的冲击韧性但降低了时效过程中的冲击韧性。     

球化工艺对热轧超高碳钢组织性能的影响

利用离异共析原理,采用不同的热处理工艺球化热轧超高碳钢。组织观察表明:热轧预处理消除了铸态下晶界网状粗大碳化物,并获得颗粒状碳化物与片状珠光体的混合组织。球化热处理时,奥氏体化温度升高、保温时间延长,碳化物颗粒的间距增大,减缓冷却速率增加碳化物的析出。对球化后超高碳钢进行拉伸力学性能试验,850℃球化后的强度很高(σ0.2=688.71MPa,σb=1005.78MPa),屈强比和伸长率分别为0.69、16.7%。拉伸后的断口形貌分析表明,超高碳钢拉伸过程中裂纹易在大颗粒碳化物处萌生、扩展。     

过时效温度对2024铝合金形变后的再结晶行为和力学性能的影响

采用力学性能检测和透射电镜（TEM）观察，研究了过时效温度对2024铝合金形变后的再结晶行为和合金力学性能的影响。结果表明：过时效温度对合金力学性能的影响较大，在250～350℃的过时效温度范围内，随温度升高，合金强度提高，350℃时效时合金的性能最好，此时σb=580MPa，δ5=9．2％，比传统处理工艺（T62）分别提高32％和84％。其原因是过时效温度间接地影响了合金随后固溶再结晶的晶粒大小。因此，为了达到细化晶粒的目的，必须严格控制过时效温度。     

时效制度对大冷变形2024铝合金力学性能的影响

采用力学性能检测、透射电镜（TEM）观察等手段，研究了时效制度对大冷变形2024铝合金力学性能的影响。结果表明，大冷变形后合金的时效响应速度提高，时效20min时就接近峰值强度，比传统处理工艺（T62）缩短6h；合金的时效强化曲线呈双峰状，时效40min左右出现第一个峰，此时合金的强度最高，抗拉强度σb=580MPa，伸长率δ5=9．2％，时效120min左右出现第二个峰，但两个峰值点的屈强比（σ0.2／σb）差别较大，第二个峰值点的屈强比明显地大于第一个峰值点的屈强比；合金的伸长率δ5值呈阶梯形变化，时效时间≤40min时，δ5≥8％；时效时间≥60min时，δ5≤5％，且随着时效时间的延长，δ5值变化不大，说明大冷变形2024铝合金存在一个临界时效时间。     

预拉伸对Al-Cu-Mg-Ag合金析出相与力学性能的影响

研究时效前预拉伸对Al-Cu-Mg-Ag合金析出相和力学性能的影响。结果表明:165℃时效前的预拉伸可提高合金的峰值硬度及强度,延长峰值时效的时间;合金的主要强化相是Ω相和θ′相,预拉伸引入的位错抑制了Ω相的析出与长大,细化Ω相的尺寸,同时促进θ′相的析出;时效前未经变形时,合金出现峰值的时间是10h,对应的σb为492MPa;时效前经4%预拉伸变形后,合金出现峰值的时间是18h,对应的σb为508MPa。     

固溶温度对Al-Zn-Mg-Cu-Cr合金组织与性能的影响

采用电子拉伸试验机、显微硬度计、洛氏硬度计、扫描电镜(SEM)、能谱分析(EDS)等对不同固溶状态下Al-Zn-Mg-Cu-Cr超高强铝合金的硬度、力学性能及组织等进行了系统的研究.结果表明,随固溶温度的升高,合金的硬度和强度不断升高,在753 K时合金的综合性能最好,σb=577 MPa,σ0.2=521 MPa,δ=11.7%;但当温度高于758 K时,合金的硬度、强度急剧下降.组织观察表明,随固溶温度的升高,时效组织中的析出相数量不断增多,均匀程度也不断提高,密度也不断增大,颗粒也变得细小,但当温度达到763K时,在合金组织内部能观察到明显的过烧现象,组织中出现复熔组织.另外,随固溶温度的升高,合金的应力腐蚀敏感性先不断降低,然后又急剧上升.其中,753K时合金的应力腐蚀敏感性最低,只有17.36%,相对于713 K时的合金抗应力腐蚀性能提高了约51.2%.     

奥氏体化温度对22Mn2SiVBS钢组织和力学性能的影响

用显微组织观察和力学性能测定法研究了Mn-Si系22Mn2SiVBS低碳空冷贝氏体钢在不同奥氏体化温度下的组织与力学性能的关系.结果表明,22Mn2SiVBS钢经1200℃奥氏体化后空冷,可以保证其显微组织以粒状贝氏体为主αK、σb和σa分别达到72.8 J/cm2、978 MPa和870 MPa,布氏硬度可达285 HBW,其综合性能可满足汽车半轴套管的使用要求.     

Fine-grained Mg–1Mn–0.5Al–0.5Ca–0.5Zn alloy with high strength and good ductility fabricated by conventional extrusion

Mg–1Mn–0.5Al–0.5Ca–0.5Zn (wt.%) alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1, followed by aging at 473 K. The microstructure was characterized by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. The mechanical properties were determined by the tensile test. The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7 μm. Area fraction of Al–Ca particles in the alloy increases significantly after peak aging. Meanwhile, both 〈a〉 and 〈c+a〉 dislocations were observed to remain in the alloy after hot extrusion. Thus, the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress, tensile yield stress, and tension fracture elongation of 320 MPa, 314 MPa, and 19.0%, respectively.     

The effect of thermal cycling on the mechanical properties of sic whisker reinforced magnesium alloy-based composites

The effect of thermal cyclings on mechanical properties at room and some elevated temperatures of SiC whisker-reinforced magnesium-matrix composites produced by squeeze casting and hot extrusion are clarified. Subsequent thermal cycling produces internal stress at the matrix/SiC whisker interfaces causing fatigue. The mechanical properties of composites are more influenced by the low thermal cycling of 298 K— 77 K than the high thermal cycling 673 K—298 K. The high thermal cycling of 673 K—298 K has only a slight affect on such mechanical properties as tensile strength and proof stress at temperatures lower than 473 K. However, at 473 K and 573 K, the thermal cyclings there almost no influence on the mechanical properties of SiC whisker reinforced AE42 alloy-matrix composites.     

Microstructure and Mechanical Properties of Mg–3Al–Zn Magnesium Alloy Sheet by Hot Shear Spinning

Hot shear spinning experiments with Mg–3.0 Al–1.0 Zn–0.5 Mn(AZ31 B, wt%) magnesium alloy sheets were conducted at various temperatures, spindle speeds and feed ratios to investigate the effects of these processing parameters on the microstructure, crystallographic texture and mechanical properties. The AZ31 B sheet displayed good shear formability at temperatures from 473 to 673 K, spindle speeds from 300 to 600 rev/min and feed ratios from 0.1 to 0.5 mm/rev. During the dynamic recrystallization process, the grain size and texture were affected by the deformation temperature of the hot shear spinning process. Each of the spun sheets presented a strong basal texture, and the c-axis of most of the grains was parallel to the normal direction. The optimal hot shear spinning parameters were determined to be a temperature of 473 K, a spindle speed of 300 rev/min and a feed ratio of 0.1 mm/rev. The yield strength, ultimate tensile strength and elongation in the rolled direction reached 221 MPa, 288 MPa and 14.1%, and those in the transverse direction reached 205 MPa, 280 MPa and 12.4%, respectively. The improved strength and decreased mechanical anisotropy resulted from the fine grain size and strong basal texture.     

Effect of deformation temperature on microstructures and properties of 7075/6009 alloy

The 7075/6009 aluminum composite ingot with the diameter of 65 mm was prepared by double-stream-pouring continuous casting. The deformation behavior and the mechanical properties of the composite ingot compressed at 543, 573, 623, 673 and 723 K were analyzed. The results show that the gradient distributions of composition and hardness in the transition layer of the composite plates still exist after plastic deformation of the ingots. Meanwhile, the thickness of the transition layer reduces from millimeter order to micrometer order. The mechanical properties of the composite plate increase with the increase in deformation temperature from 543 K to 673 K. The best mechanical properties of the 7075/6009 aluminum composite are: σ_b=381 MPa, σ_0.2=322 MPa and δ=16.6%. The appropriate deformation temperature range is (0.75–0.85)T_M, where T_M is the melting point of 7075 alloy.     

Effect of post equal-channel-angular-pressing aging on the modified 7075 Al alloy containing Sc

The effect of post-ECAP low-temperature aging on mechanical properties of the 7075 Al aluminum alloy containing Sc (7 × 51) after a single pressing was examined. The best aging effect on strengthening was achieved at 373 K after 20–30 h. After the post-ECAP aging treatment, the yield stress and UTS of the 7 × 51 alloy have increased to 680 MPa and 730 MPa, respectively. This achievement is remarkable when compared with the 7075 Al alloy conventionally ECAP processed for three passes exhibiting the YS of 667 MPa and UTS of 677 MPa. The post-ECAP aging was also effective in improving the tensile ductility of the ECAPed alloy. The unECAPed and ECAPed 7 × 51 Al alloys before or after aging at 373 K showed a big difference in strain hardening ability. According to the model assessing the extent to which the hardening and softening mechanisms are active during the plastic deformation of the materials, the low strain hardening rate of the ECAPed alloy could be attributed to a significant contribution to softening by cross slip and a small contribution of precipitation to hardening.     

固溶时效处理对TC6合金组织与性能的影响

采用OM、SEM、XRD、维氏硬度以及力学性能测试等方法,研究了固溶时效处理对TC6合金显微组织、相结构以及力学性能的影响。结果表明：TC6合金经过900 ℃固溶处理后,合金由片层α相、针状马氏体α′相以及β相组成;而经过1000 ℃固溶处理后,合金主要由针状α′马氏体相和β相组成。对不同固溶温度下的合金样品进行时效处理,针状α′马氏体相完全分解为α相和β相。并且随着时效温度升高,β相的相对含量逐渐增大。通过对比,TC6合金经过900 ℃固溶后在500 ℃下进行时效处理后综合力学性能达到最佳,此时的抗压强度和屈服强度为2000 MPa、1061 MPa,硬度值为499 HV0.2。     

Zr和Mn元素微合金化增强耐高温铝铜合金的热稳定性和力学性能

系统研究Al?5％Cu(AC)和Al?5％Cu?0.2％Mn?0.2Zr％(ACMZ)合金在温度为573～673 K的高温热稳定性和力学性能.结果表明,微合金化添加Zr和Mn元素对573 K主要强化相θ′相的稳定起到至关重要的作用.同时,高温拉伸结果表明,573 K热暴露200 h后,ACMZ合金强度为(88.6±8....     

Superplasticity and diffusion bonding of magnesium alloy ZK60

1 INTRODUCTIONRecently , the use of magnesium alloys asstructural materials has significantlyincreased,forits good damping capacity , di mension stability ,machinability and lowcasting costs . But magnesi-umalloys normally exhibit lowductility near roomtemperature because of their HCP structure .Therefore ,it is necessary to i mprove the ductilityof these alloys for their use as structural compo-nents[1 3].In manufacturing,superplastic forming is of-ten combined with diffusion bonding, w…     

时效温度对Ti-5Al-4Zr-10Mo-3Cr钛合金微观组织及力学性能的影响

研究了Ti-5Al-4Zr-10Mo-3Cr合金经过β相区固溶(880 ℃)、不同温度时效(540~620 ℃)处理后次生α相(α_s)析出形貌及其对力学性能的影响。结果表明:随着时效温度由540 ℃升高至620 ℃,合金中析出α_s相片层厚度由0.030 μm增加到0.142 μm,屈服强度由1353 MPa降低至1074 MPa,断后伸长率由2.5%升高至11.4%,即时效析出的微米级片层α_s能够显著调控合金的力学性能。此外,时效温度升高使合金的拉伸断裂由沿晶脆性断裂为主转变为韧窝穿晶为主的韧性断裂方式。Ti-5Al-4Zr-10Mo-3Cr合金时效析出的片层状α_s相的厚度大于0.1 μm,合金的断后伸长率≥6%。当时效温度为600 ℃时,合金的硬度为387 HV10,抗拉强度为1182 MPa,伸长率为8.5%,具有良好的强塑性匹配。     

Influences of aging temperature and time on microstructure and mechanical properties of 6005A aluminum alloy extrusions

The influences of aging time and aging temperature on the microstructure and mechanical properties were investigated on the 6005A aluminum alloy extrusions. Artificial aging was performed on the alloy extrusions. The aging times were 4, 8 and 12 h, and the aging temperatures were 150, 175 and 200 °C. The results show that the morphologies of the coarse Al(Fe,Cr)Si particles formed in the extrusion process are evolved from granular to rod-like particles with the increase of the aging temperature or the aging time. The volume fraction of the submicron precipitates reaches the maximum value at the aging temperature of 175 °C. AlFeSi particles in size of 1-3 μm are precipitated at the grain boundaries at the aging temperature of 200 °C. The room temperature mechanical properties of the extrusions are more sensitive to the aging temperature than to the aging time. The optimum and stable mechanical properties are achieved when the aging procedure 175 °C, 4-8 h has been performed on the extrusions. The tensile strength and the yield strength in the longitudinal direction of the aged extrusions are more than 300 MPa and 270 MPa, respectively.