低碳微合金容器钢经调质处理后的组织与性能

本文研究了含碳0.09%的低碳微合金容器钢的组织与性能。结果表明该钢经调质处理(960℃×1.5 h+630℃×1.5 h)后,获得的性能为:0σ.2=641 MPa,σb=742 MPa,δ=20%,ψ=75%,AKV=321 J,HB=204。室温组织为铁素体及弥散的析出物。     

自动化机械用Si-Mn系超高强度淬火钢焊接接头的微观组织和力学性能

采用不同点焊工艺对Si-Mn系超高强度淬火钢与普通低碳钢进行焊接,研究焊接接头的微观组织和力学性能。结果表明,焊接接头处抗剪强度随焊接电流增大和焊接时间的延长而逐渐增大,且焊接电流的影响较为明显。但是,焊接电流过大或焊接时间过长,均会引起飞溅,导致抗剪强度降低。     

回火工艺对在线淬火12MnNiVR钢组织和性能的影响

利用SEM、TEM等分析方法及性能检测研究了回火工艺参数对在线淬火12MnNiVR钢组织及性能的影响。结果表明,在线淬火后的12MnNiVR钢板淬火组织为淬火马氏体加少量淬火贝氏体的复合组织;经(625～655)℃×60min回火可以获得均匀的回火贝氏体组织,其综合力学性能均超过要求。抗拉强度可达到628MPa以上,屈服强度可达562MPa以上,伸长率达21%以上,-20℃冲击功达到220J以上。     

Influence of Direct Quenching on Microstructure and Mechanical Properties of Steel Plate for Large Oil Storage Tanks

The influence of direct quenching on microstructure and mechanical properties of high performance steel plates for large oil storage tanks was studied. The direct quenched and tempered (DQ&T) steel plates were rolled at different finish rolling temperatures (1113 and 1173 K), and their microstructures and mechanical properties were compared with those of reheat quenched and tempered (RQ&T) steel plate. The optical microscopy of the DQ steel shows deformed grains elongated along the rolling direction, while complete equiaxed grains are visible in RQ steel. Transmission electron microscopy (TEM) of the DQ steel shows refined lath martensite with high density of dislocations, which acts as preferred precipitation sites for NbC or Nb(C,N) particles during tempering. In all the plates, strength decreases with increasing tempering temperature. The strength of RQ steel increased significantly compared with that of DQ steel at the higher tempering temperature, which leads to better tempering resistance in DQ steels. The optimum combination of strength and toughness (yield strength (YS) reaches 585 MPa, tensile strength (TS) 667 MPa, and Charpy impact energy at 253 K of 291 J) in the DQ steels is achieved by quenching at 1113 K and tempering at 923 K.     

初始组织对低合金调质高强钢热处理后力学性能的影响

本文以开发屈服强度为960Mpa级工程机械用调质高强钢为目的,分析了不同的轧制及轧后冷却工艺对实验钢热处理后力学性能的影响。结果表明,不同的轧制及轧后冷却工艺决定了实验钢热处理前的初始显微组织,进而影响其热处理后的力学性能。实验钢经控制轧制并层冷至600℃后空冷,得到的初始组织为粒状贝氏体及少量的马氏体,其中M/A组元更多地呈条状分布在基体上'经调质处理后,实验钢获得了较高的强韧性,R_el各项为1033Mpa,Rm为1053Mpa,Akv（-40℃）指标均达到相关标准要求。     

热处理对钽板组织和力学性能的影响

借助于力学性能试验、金相显微镜和扫描电镜等分析了热处理对纯钽再结晶组织和力学性能的影响.结果表明:对于预变形10％的1 mm厚和预变形20％的1.6 mm厚的薄板试样,900℃保温15、30、45 min退火处理后,晶粒尺寸细化效果不明显;预变形和退火处理使两者硬度和抗拉强度显著提高,伸长率则大幅降低.随保温时间延长,1 mm厚试样的抗拉强度和屈服强度逐渐提高,而1.6 mm厚试样的抗拉强度先降低后升高,伸长率均依次降低.断口形貌的分析与力学性能结果一致.     

Microstructure and Mechanical Properties in Friction Stir Welded Thick Al–Zn–Mg–Cu Alloy Plate

In this work, 20-mm-thick aluminum-alloy plates were joined via friction stir welding. The temperature gradient was reduced by reducing the surface welding heat input to achieve uniformity of the mechanical properties across the thick plate joints. The welding temperature was measured using thermocouples. The microstructures were observed via electron backscatter diff raction and transmission electron microscopy. The tensile properties of the samples sliced along the thickness direction of the j...     

热处理对Ti-5331合金板材组织及力学性能的影响

研究了核反应堆壳体用Ti-5331合金热轧板材在不同退火温度下的显微组织与力学性能。结果表明:Ti-5331合金板材在相变点以下随着退火温度的升高,初生α相含量逐渐减少,β转变相含量明显增加。当退火温度为700℃时,开始发生静态再结晶,800℃时为等轴组织,900℃时为双态组织,950℃时为网篮组织。随着退火温度的升高,合金板材的抗拉强度先下降后上升,屈服强度呈下降趋势,屈强比逐渐减小;当退火温度在相变点以下时,板材冲击韧性随退火温度升高呈上升趋势,当超过相变点后冲击韧性急剧下降;退火温度对塑性影响较小。经900℃×1 h/AC退火处理的Ti-5331合金板材有着较好的综合性能,抗拉强度为920 MPa,延伸率为15%,V型缺口冲击韧性达到93 J/cm~2。     

热处理对AH36船板钢微观组织和力学性能的影响

研究了正火对AH36船板钢微观组织和力学性能的影响。结果表明,AH36船板钢随正火温度的升高,屈服强度和抗拉强度降低,断后伸长率和冲击韧度先升后降,力学性能的变化与位错密度和晶粒尺寸密切相关。AH36船板钢的最佳正火温度为900℃,经900℃正火后,钢板晶粒细小均匀,异常偏析带完全被珠光体替代,断口分层现象消失,塑韧性显著改善。     

热轧历程对MGH754合金板材组织与性能的影响

通过扫描电镜成像系统与光学显微镜分析研究了不同热轧历程对MGH754合金板材组织衍变和性能的影响.研究表明:MGH754合金板材动态再结晶的晶粒大小随着热轧温度的升高而增加;低温后,MGH754合金板材显微硬度很高,说明合金内部仍旧存在高的位错密度.初轧温度为1150℃,终轧温度为1050℃时,合金退火未发生完全的二次再结晶.     

Study on Microstructure and Mechanical Properties of Friction Stir Welded Aluminium Alloy Thick Plate

对14 mm厚板铝合金搅拌摩擦焊(FSW)接头焊核区微观组织、整体和分层切片力学性能进行了研究。结果表明, 当旋转速度为400 r/min, 焊接速度为60-100 mm/min时, 接头抗拉强度σ　b、屈服强度σ0.2和延伸率δ随焊速的升高而降低。焊缝分层切片的σ b, σ　0.2和δ上部最高, 分别达到了186.7 MPa, 100.3 MPa和14.1%;下部最低, 分别为157.5 MPa, 80.2 MPa和10.1%。微观断口中存在大量的网状韧窝, 切片上部韧窝最深, 焊缝根部可见沿晶界的二次裂纹和浅韧窝。显微硬度分布为焊缝上部高于下部, 沿焊缝中心呈不对称分布. 焊核区上部等轴再结晶晶粒尺寸大于焊缝下部. 焊核区上部的第二相粒子相对下部更均匀和细小, 强化作用增强.     

贝氏体-马氏体钢板的组织与性能

研究了贝氏体-马氏体耐磨钢板的组织及力学性能。结果表明，在低碳贝氏体钢基础上，通过加入一定量的硅元素，利用其在贝氏体组织转变过程中抑制碳化物析出的作用，得到由非等轴铁素体加马氏体和残留奥氏体(M-A)岛或由板条状铁素体及其板条间残留奥氏体(Ar)膜组成的贝氏体一马氏体组织，因此其性能既具有高强度、高硬度，又具有较高的低温冲击韧度。     

A Comparison of Fatigue Properties of Austempered Versus Quenched and Tempered 4340 Steel

This study was conducted to determine if austempered 4340 steel had different fatigue resistance compared to quench and tempered (Q&T) 4340 steel with an identical hardness of nominally 45 HRC and an identical yield strength of nominally 1340?MPa (194?ksi). Strain-life and stress-life fatigue testing was conducted at room temperature under identical test conditions. The standard array of strain-life and stress-life regression constants was obtained. The two heat treatments produced virtually identical total strain-life curves and fatigue limits at 5 million cycles. However, the two materials exhibited different trends in the elastic and plastic strain regimes. The austempered steel exhibited greater high cycle fatigue (finite) lives than the Q&T samples at comparable elastic strain amplitudes in strain-life fatigue testing and at comparable stress amplitudes in stress-life fatigue testing. However, the Q&T samples exhibited greater low cycle fatigue lives than the austempered samples at comparable plastic strain amplitudes in strain-life testing. Although both materials generally exhibited similar fatigue fracture characteristics, the overload regions of the Q&T samples were composed entirely of dimple rupture, whereas the austempered samples exhibited both dimple rupture and quasicleavage.     

冷却工艺对微合金化高强度钢板组织与力学性能的影响

以550MPa级微合金化高强度钢为研究对象,研究了冷却模式和卷取温度对钢板力学性能与显微组织的影响。结果表明,冷却方式对钢板的组织与性能影响较小。卷取温度为605℃时,抗拉强度达到702 MPa,-20℃冲击功为63.4 J。     

R60702/TA2爆炸焊接复合板微观组织及力学性能研究

通过爆炸焊接的方法实现了R60702板与TA2板的结合。利用光学显微镜、扫描电镜、能谱仪、显微硬度计对热处理前后锆-钛结合界面的微观组织、元素扩散、显微硬度进行了分析;并研究了热处理前后复合板的力学性能和断口形貌。结果表明：爆炸焊接后,锆-钛结合界面呈波状,界面附近产生塑性变形和轻微的元素扩散,随着塑性变形的减弱界面两侧显微硬度也逐渐减小。热处理后,界面元素扩散明显,组织发生再结晶,显微硬度、抗拉强度、剪切强度较热处理前降低,而复合板的塑韧性得到提高。热处理后的复合板弯曲性能良好。     

The Effect of Direct and Cross-Rolling on Mechanical Properties and Microstructure of Severely Deformed Aluminum

Severely deformed commercial pure aluminum sheets by constrained groove pressing are direct and cross-rolled. The grain size evolution and dislocation density during rolling are studied using Williamson-Hall analysis on x-ray diffraction patterns of the deformed samples. These results and optical microscopy observations show that subsequent direct or cross-rolling of constrained groove pressed aluminum can produce elongated fine grains. The minimum crystallite size is achieved after cross rolling of constrained groove pressed samples. By direct rolling or cross-rolling of annealed sheet, the maximum intensity in x-ray diffraction patterns remains on (200) like annealed aluminum but direct rolling or cross-rolling of constrained groove pressed sheets changes the maximum intensity from (111) for constrained groove pressed sheets to (220). Also, mechanical properties are studied using tensile test and hardness measurement. The results show that cross rolling on constrained groove pressed samples is more effective than direct rolling in mechanical properties improvement.     

25MnV钢"零保温"淬火组织与性能的研究

采用正交组合回归设计试验方法,研究了“零保温”淬火工艺对25MnV钢组织和性能的影响,分析了“零保温”淬火条件下奥氏体转变的特征。结果表明,在830—930℃“零保温”淬火时,随着加热温度的升高,25MnV钢的强度、硬度升高,经930℃“零保温”淬火后该钢具有较高的强度和硬度。“零保温”淬火后可获得细小的板条状马氏体组织。25MnV钢“零保温”淬火工艺可以代替传统的保温淬火热处理工艺。     

变形量和回火工艺对高强钢厚板组织性能的影响

研究了轧制变形量和回火工艺对高强钢厚板微观组织和力学性能的影响。结果表明,第Ⅰ、Ⅱ阶段变形量从0.64/0.50变为0.52/0.62,比降低30℃终轧温度对提高钢板屈服强度和抗拉强度的贡献更大。回火后,钢板的强度由位错密度降低导致的位错强化减弱和细小析出物析出导致的析出强化增强交互影响决定,钢板强度降低。     

Influence of Asymmetric Rolling Parameters on the Microstructure and Mechanical Properties of Titanium Explosive Clad Plate

对钛钢爆炸复合板进行轧制处理,可以得到较薄较宽的复合板。利用光学显微镜、扫描电子显微镜、透射电子显微镜、X射线衍射仪、拉剪实验研究了不同的轧制参数对钛-钢爆炸轧制复合板界面组织特征和性能的影响。结果表明:降低轧前热处理温度或开轧温度,都会提高复合板的界面结合强度。在轧前热处理过程中,由于铁、碳元素的扩散,在界面上形成Ti C和Ti-Fe金属间化合物,使复合板剪切强度下降。然而,在轧制的过程中,这些界面化合物在轧制压力的作用下被压碎,呈弥散分布,阻止界面裂纹的扩展,界面结合强度有所提高,因此,增加轧制压下量可以提高界面的结合性能。