The influence of temporary hydrogenation on ECAP formability and low cycle fatigue life of CP titanium

It is generally believed that thermo-hydrogen processing has a beneficial effect on tensile ductility and fatigue properties of titanium. This study was concerned with investigating whether this also applies to titanium of commercial purity (CP) with an ultrafine-grained structure obtained by equal-channel angular pressing (ECAP). It was shown that despite the possibility to manipulate the microstructure of titanium the thermo-hydrogen processing offers, temporary hydrogenation was not able to improve ductility and low cycle fatigue life of CP titanium over the levels achievable by straight ECAP.     

ECAP结合热处理工艺改性2224铝合金

研究应用ECAP法与热处理工艺相结合的方法改性2224铝合金的过程,对改性2224铝合金的力学性能及显微组织进行比较分析.结果表明,退火态2224铝合金经ECAP挤压后,进行固溶和时效处理,明显提高了合金的力学性能,细化了合金的晶粒.与通常的变形2224铝合金相比,改性2224铝合金更有实际应用价值.     

等径角挤压法工艺路线影响材料显微组织演化的研究概况

简要介绍了等径角挤压法的工艺特点和基本原理，概述了等径角挤压法的不同工艺路线影响材料显微组织演化的研究情况．     

Three Nb single crystals processed by equal-channel angular pressing—Part II: Mesoscopic bands

Three high-purity Nb single crystals with different orientations are deformed by equal-channel angular pressing (ECAP) at room temperature for one pass. Large misorientation bands (LM-bands) are observed in two single crystals, but with different appearances. An analysis of slip activity is carried out to link the primary slip systems to the observed microstructures. It is found that the LM-bands are parallel to the primary slip systems at the beginning of deformation. Further characterization of the bands shows that their end orientations tend to have a stable configuration with respect to the simple shear plane and the direction. Based on these results and comparison with earlier works, the forming process of the LM-bands during ECAP is proposed.     

Large-scale manufacturing of aluminum alloy plate extruded from subsize billet by new porthole-equal channel angular processing technique

To manufacture plate by the combination of equal channel angular processing (ECAP) and porthole die extrusion techniques, a novel technique, namely portholes-equal channel angular processing (P-ECAP), was studied. Extrusion of AL6005A plate used for the bullet train plate was investigated by finite element method. The relevant porthole dies involving ECAP technique in channels were designed. Dimensional changes in the scrap part of the extrudate obtained after extrusion from the P-ECAP die, with different channel angles, were predicted. Effects of the channel angle and extrusion speed on the maximum temperature of the workpiece and other field variables were evaluated. At the channel angle of 160° of P-ECAP dies, the extrudate exhibited the optimal performance and the least amount of extrudate scrap was obtained. The optimal extrusion speed was 3–5 mm/s. Moreover, with the increase in ram speed from 1 to 9 mm/s, the peak extrusion load increased by about 49% and the maximum temperature was increased by about 70 °C. The effective strain exhibited ascending trend in the corner of the ECAP deformation zone. In the solder seam and the side of die bearing of extrudate, the maximum principal stresses were tensile stress.     

扩展路径低温ECAP及时效热处理对Cu0.6Cr合金的组织和性能影响

采用光学显微镜和X射线衍射仪对Cu0.6Cr合金经低温扩展路径等通道转角挤压（ECAP）后的组织演变规律进行了研究。采用扫描电子显微镜和能谱仪研究了Cu0.6Cr合金经不同时效热处理条件后的晶粒大小、析出相分布规律和断裂特征。并且分别测试了合金经低温ECAP和低温ECAP+时效热处理后的抗拉伸强度、硬度和导电率。结果表明,Cu0.6Cr合金经低温ECAP变形后形成明显细化且相互交割的纤维组织,并且合金在变形中始终保持（111）面的择优取向。时效热处理的合金变形量越大,析出相的数目和尺寸就越大,第二相析出速率也越快。5道次合金经450 ℃时效2 h后的抗拉伸强度为568.1 MPa,维氏硬度为1624.8 MPa,导电率为82%IACS。     

ECAP结合退火工艺制备铜铝双金属复合棒材的界面组织及结合性能

利用室温4道次ECAP挤压结合退火工艺成功制备铜铝双金属复合棒材。采用扫描电镜（SEM）、能谱分析（EDS）、X射线衍射分析（XRD）和电子背散射衍射（EBSD）等方法研究铜铝双金属复合棒材结合界面微观组织,并通过剪切试验测试其界面结合强度。结果表明,在ECAP剧烈剪切作用下,铜铝双金属复合棒材首先通过塑性变形在界面处产生机械结合,后续退火热处理促进了铜铝原子之间相互扩散,在压力、温度和浓度梯度综合作用下,Cu/Al界面处形成了良好的冶金结合,界面层厚度约为1.47 μm,生成的金属间化合物主要为CuAl2;界面层内晶粒细小、均匀,为大角度晶界结构的超细晶组织,无明显的择优取向。铜铝双金属复合棒材平均剪切强度为28.94 MPa,界面结合质量良好,剪切破坏形式主要为脆性断裂。     

The formation of PSB-like shear bands in cyclically deformed ultrafine grained copper processed by ECAP

Cyclic deformation was performed on ultrafine grained copper processed by ECAP. Shear bands (SBs) and adjacent microstructures were investigated using electron channeling contrast in scanning electron microscope. The possible formation mechanism of SB was discussed based on the characteristic distribution of defects introduced by ECAP.     

Fatigue properties of fine grained magnesium alloys after severe plastic deformation

Fine grained AZ31 and AZ61 magnesium alloys produced by equal channel angular pressing (ECAP) were tested for investigating tensile and fatigue properties, including microstructure, monotonic tensile flow, fatigue life and crack growth rate. For the two alloys, the yield stress of the ECAPed sample was lower than that of the unECAPed (=as received) sample, because of the fact that the softening effect due to texture anisotropy overwhelmed the strengthening effect due to grain refinement. Grain refinement of the AZ31 and AZ61 alloys through ECAP was found not to be significantly effective in increasing fatigue strength.     

两种塑性变形加工1060纯铝的组织和性能研究

采用等通道角挤压变形和累积叠轧焊两种大塑性变形方法对1060纯铝进行了加工，研究分析了纯铝在加工后的微观组织和力学性能变化和规律。结果表明：在相同的累积变形条件下，ARB和ECAP都能实现材料的晶粒细化和力学性能改善的目的。但南于两种塑性加工方式细化晶粒的机理和加工工艺不同．所以晶粒细化程度和力学性能的改善程度有所差别。ARB法将晶粒最小可以细化到500nm左右，ECAP法能细化晶粒到大小约为1μm。