构建企业技术联盟的强化机制

企业技术联盟是指两个或两个以上的企业互相联合致力于技术开发的行为。企业技术联盟强调技术开发资源的互补或加强。实施企业技术联盟 ,不仅得到了资源互补或加强 ,更重要的是企业之间在合作技术开发过程中相互作用、相互影响、协调运作 ,共同构建了一个新的技术开发系统。企业技术联盟的目的是增加进入市场的机会 ,开发新产品占领市场是企业的刚性需要 ,是不容改变和必须满足的。为达到这一目的 ,满足社会经济发展需要 ,使企业技术联盟系统运行更好 ,必须构建企业技术联盟的强化机制。

Effect of thermo-mechanical treatment on microstructure and mechanical properties of wire-arc additively manufactured Al-Cu alloy

Wire-arc additive manufacture(WAAM)has great potential for manufacturing of Al-Cu components.However,inferior mechanical properties of WAAM deposited material restrict its industrial application.Inter-layer cold rolling and thermo-mechanical heat treatment(T8)with pre-stretching deformation between solution and aging treatment were adopted in this study.Their effects on hardness,mechanical properties and microstructure were analyzed and compared to the conventional heat treatment(T6).The results show that cold rolling increases the hardness and strengths,which further increase with T8 treatment.The ultimate tensile strength(UTS)of 513 MPa and yield stress(YS)of 413 MPa can be obtained in the inter-layer cold-rolled sample with T8 treatment,which is much higher than that in the as-deposited samples.The cold-rolled samples show higher elongation than that of as-deposited ones due to significant elimination of porosity in cold rolling;while both the T6 and T8 treatments decrease the elongation.The cold rolling and pre-stretching deformation both contribute to the formation of dense and dispersive precipitatedθ′phases,which inhibits the dislocation movement and enhances the strengths;as a result,T8 treatment shows better strengthening effect than the T6 treatment.The strengthening mechanism was analyzed and it was mainly related to work hardening and precipitation strengthening.

Low-carbon advanced nanostructured steels:Microstructure, mechanical properties, and applications

Low-carbon advanced nanostructured steels have been developed for various structural engineering applications, including bridges, automobiles, and other strength-critical applications such as the reactor pressure vessels in nuclear power stations. The mechanical performances and applications of these steels are strongly dependent on their microstructural features. By controlling the size,number density, distribution, and types of precipitates, it is possible to produce nanostructured steels with a tensile strength reaching as high as 2 GPa while keeping a decent tensile elongation above 10% and a reduction of area as high as 40%. Besides, through a careful control of strength contributions from multiple strengthening mechanisms, the nanostructured steels with superior strengths and low-temperature impact toughness can be obtained by avoiding the temper embrittlement regime. With appropriate Mn additions, these nanostructured steels can achieve a triple enhancement in ductility(total tensile elongation, TE of ~30%) at no expense of strengths(yield strength, YS of ~1100 to 1300 MPa, ultimate tensile strength, UTS of ~1300 to 1400 MPa). More importantly, these steels demonstrate good fabricability and weldability. In this paper, the microstructure-property relationships of these advanced nanostructured steels are comprehensively reviewed. In addition, the current limitations and future development of these nanostructured steels are carefully discussed and outlined.