回火参数对NiCrMoV转子钢焊缝时效韧性的影响

为了揭示回火参数对耐热钢焊缝时效韧性的影响机理,针对采用不同回火参数处理的超临界汽轮机低压转子模拟件焊缝进行了时效韧性的研究。研究发现当回火温度利于碳化物析出聚集时,经过350℃×3 000 h时效后室温冲击韧性明显下降。通过对金相试样进行扫描电镜观察发现,时效后试样中的析出物较时效前显著增加。透射电镜观察发现析出物聚集长大后基体内的位错密度明显下降,因此热强性退化。若适当提高回火温度,经过相同的时效处理后仍然能够保持较高的冲击韧性,且析出物没有明显变化。由此证明,回火参数对碳化物析出行为的作用是其影响时效韧性的主要途径。本研究可为回火参数的优化提供一定参考。

浅析20g时效冲击韧性偏低原因

针对检验中出现的时效冲击值偏低的情况,统计了近3年济钢中板厂20g钢板的性能情况,对成分和性能进行回归分析,并且检验了夹杂物、金相组织和氧氮含量。结果表明,影响时效冲击韧性的主要因素是碳、硫和钛含量以及夹杂物等。建议通过严格控制碳硫含量,提高钛含量和钢水纯净度,以提高钢板的时效冲击韧性。

提高16Mng钢板时效冲击韧性工艺控制研究

分析了影响16Mng钢板的时效冲击韧性的主要因素，讨论了16Mng钢板生产的工艺控制要点，提出了一套优化的工艺参数，并对控制效果作了分析。

Q370q桥梁钢横向和纵向低温时效冲击韧性对比分析

对高等级桥梁钢Q 370q的横、纵向低温时效冲击軔性进行了试验,并对试验数据进行了分析.结果表明 - 4 0 ~ 0 ℃横、纵向低温时效冲击钿性的比值在0 .4 ~ 0.55 之间,可以采用横向时效冲击试验替代纵向时效冲击试验,减少钢板在轧制方向上的取样长度,达到提高成材率的目的.

薄规格高韧性船板轧钢工艺探讨

针对韶关钢铁集团公司在用常规热轧工艺开发薄规格D级船板时出现应变时效不合问题进行了研究和工业试验。通过对钢板的成分设计和4种不同工艺方案的比较,得出采用Al、Nb/V微合金化,并采用两阶段控轧+轧后控冷工艺,可生产出合格的薄规格D级船板。

时效温度对马氏体沉淀硬化不锈钢0Cr15Ni5WMoVNb力学性能的影响

0Cr15Ni5WMoVNb钢(%:0.068C、14.54Cr、5.32Ni、0.88W、0.92Mo、0.20V、0.10Nb)经5 t中频感应炉+2 t真空电渣重熔炉冶炼,经锻造、热轧成Φ45 mm棒材,试样经1 000℃30 min固溶空冷+-70℃2 h冷处理后进行400～600℃4 h时效空冷。试验结果表明,在450℃时效0Cr15Ni5WMoVNb钢的强度最大,以准解理断裂为主,冲击功低为40 J,随时效温度上升,冲击功显著上升,强度下降,在510℃时效该钢有良好的强韧性,抗拉强度R_m 1300 MPa,屈服强度R_(p0.2)1100 MPa,冲击能A_(KV) 100 J。

Microstructure and mechanical properties of alloy 617B

The microstructure and mechanical properties of alloy 617 B in the process of 5000 h aging at 750 °C were systematically investigated by means of SEM, TEM and mechanical analysis. M23C6 particles were dispersed inside grains and distributed discontinuously along grain boundaries and γ′ phases were situated at intragranular sites in the process of aging. The size of precipitates increased with increasing aging time. Inter- and intra-granular carbide and γ′ phase particles inside grains resulted in the precipitation strengthening of this aged alloy, enhancing the strength and hardness. The aged alloy possessed good stabilities of hardness and strength during aging. An obvious decrease of the toughness of this aged alloy was due to γ′ phase particles limiting plastic deformation to the area nearby grain boundaries, resulting in the occurrence of crack along grain boundaries. Additionally, the intergranular cracks apparently led to a decrease in the toughness for this aged alloy due to carbide particles at grain boundaries. The toughness of this aged alloy was fairly stable possibly due to the unchanged distribution of the precipitates during aging.

Effect of heat treatment on microstructure and mechanical property of extruded 7090/SiC_p composite

The ultra high strength SiC particles （SiCp） reinforced Al-10%Zn-3.6%Mg-1.8%Cu-0.36%Zr-0.15% Ni composite was prepared by spray co-deposition. Microstructures of the extruded and different heat-treated bars were analyzed by transmission electron microscopy （TEM） and energy dispersive spectrometry （EDS）. Grain size of the composites prepared by two-stage solution is smaller than that by single-stage solution. After single-stage solution aging treatment, fine precipitates of both η and AlZnMgCu-rich phase can be found both intragranularly and intergranularly. While after the two-stage solution, an amorphous Si-Cu-Al-O （5 nm） layer appears at the interface. The addition of Ni and Zr modified the influence of the two-stage solution and inhibited the growth of the 7090/SiCp composite grain size. Heat treatments can significantly improve the fracture toughness of the composite. The fracture toughness first decreases then increases with the elongation of the aging time.

Properties of AA7075 aluminum alloy in aging and retrogression and reaging process

A retrogression process was applied to AA7075alloy at180,240and320°C for1,30,50,70,90and120min.After the retrogression,aging treatment was reapplied with T6conditions(120°C,24h).The mechanical properties of aged samples were determined by V-Charpy and hardness tests and also,physical properties of samples were determined by electrical conductivity tests.Moreover,microstructural properties were characterized by light microscope and transmission electron microscope.The results show that the effects of the temperature and the duration of the retrogression and reagent on the impact toughness and hardness are related to the precipitates at the grain boundary.

Influence of aging on microstructure,mechanical properties and stress corrosion cracking of 7136 aluminum alloy

The microstructure,mechanical properties and stress corrosion cracking(SCC)of 7136 aluminum alloy under T 6,T 79 and T 74 aging treatments were studied and the effects of microstructure on the mechanical properties and SCC were discussed.The results show that the ultimate tensile strength and yield strength of the aging 7136 alloys follow this sequence from high to low:T 6>T 79>pre-aging>T 74.For 7136 Al alloy after T 6 aging,the average diameter of the precipitates was(5.7±1.7)nm,and the diameter of 60.7%(number fraction)precipitates was 2−6 nm,leading to a good precipitation strengthening.The K_(IC)of T 74-aging alloy is 38.2 MPa·m^(1/2),which is 26.1%more than that of T 6-aging alloy and 17.5%more than that of T 79-aging alloy.The improved fracture toughness in T 74-aging alloy is mainly due to the reduction of the strength difference between intragranular and grain boundary.The SCC resistance of the aging 7136 alloys follows this sequence from high to low:T 79>T 74>T 6.After T 79 aging,the discontinuous grain boundary precipitates and narrow precipitate free zones were obtained in 7136 alloy,which was beneficial to SCC resistance.

复合材料出口导向叶片RTM成型流场仿真模拟研究

针对航空发动机复合材料出口导向叶片RTM(Resin Transfer Molding,树脂传递模塑)成型工艺,开展了高韧性短时效树脂基体的工艺特性及低渗透率铺层结构预制体的渗透特性研究,并结合PAM-RTM软件对其RTM成型工艺方案进行了研究,获得了适用于高韧性短时效树脂/低渗透率铺层结构复合材料出口导向叶片的快速RTM成型工艺方法。

低碳结构钢脆性断口的光镜观察

本文介绍了应用光学显微镜、对低碳结构钢在进行冲击韧性测试后的脆性断口进行观察、拍照的方法和所取得的成果。列出了对20g和16MnR钢板冲击试样脆性断口观察后所拍照的断口形貌图片。揭示了这些断口属于解理和准解理断裂,断裂时裂纹核产生于钢中的氮、碳化钛和沿晶析出的三次渗碳体,穿晶断裂的形貌具有典型的扇形和河流状花样的解理阶。并且还提供了16MnR钢板具有大量粒状贝茵体的基体组织时的断口光镜形貌。从而、为提高20g和16MnR钢板的质量提供了可靠信息。