外文翻译--热等静压合并过程的发展和解决铝铸件浸渗的热处理过程的成本效益中文

外文翻译--热等静压合并过程的发展和解决铝铸件浸渗的热处理过程的成本效益中文内容摘要：

of A356, the precipitates are Mg2Si. In order to prevent the Mg2Si particulates from again precipitating out of solution, a rapid quench is employed. Quenching the castings also insures that the homogenization that results from the solutionizing step is maintained. To attain maximum strength in the casting a precipitationhardening or aging heat treatment is employed. Artificial aging takes place at slightly elevated temperatures, 165176。 C, while natural aging occurs at room temperature. The homogenization attained in the previous steps insures a uniform dispersion of the particulates grown in the aging step. Artificial aging to reach maximum strength deems the temper of the casting as T6, where natural aging gives the casting the temper designation T4. Hot isostatic pressing, or HIP, is typically performed before heat treatment and is a means of eliminating the porosity in castings. HIP surrounds the casting with a pressurized gas, which applies a hydrostatic force to the surface of the casting while at elevated temperature to facilitate material flow. The dominant densification mechanism in the casting during the initial stages of the HIP process is plastic flow. As castings spend additional time at maximum temperature and pressure the dominant densification mechanisms change, first to powerlaw creep, then to diffusional creep mechanisms (NabarroHerring, and Coble creep). The overall effect is the welding of isolated porosity within the casting [Atkinson]. Due to the time intensive nature of the HIP process, several variants of the original process have been developed to maximize the returns of the HIP process while minimizing process time and cost for the production of critical aluminum castings. Liquid hot isostatic pressing (LHIP) uses a heated inpressible liquid as the pressurizing media [Chandley]. The guiding principle behind this manufacturing process states that the majority of the time spent in the traditional gas HIP process is spent pressurizing and depressurizing the pressible gas media. In the LHIP process, the castings are immersed in the liquid salt bath and the entire salt bath container is pressurized via a hydraulic ram very quickly. By this method, maximum pressure can be reached in seconds rather then the several hours required in the HIP process. Furthermore, this process could be integrated into a continuous casting process [Chandley]. However, time spent at peak pressure for an A356 casting in the LHIP process is only about thirty seconds [Romano et al.], which does not allow any of the previously mentioned timedependant creep mechanisms to occur. Bodycote PLC has taken another approach to reducing the cost of the HIP process for aluminum castings. The Densal process is a proprietary HIP process that has tailored the HIP process specifications and hardware specifically for aluminum castings. Time spent at temperature and pressure allows diffusional creep mechanisms to take place. It has been estimated that the Densal process reduces the cost of HIP for aluminum castings by as much as seventy percent [Mashl et al.]. However, further gains in Densal process economy may be possible. Due to the similarity of the process temperatures of solution heat treatment and the Densal process, integrating these two processes could yield even further reduction in the cost of HIP and heat treatment for aluminum castings. The purpose of this thesis is to develop and evaluate the feasibility of this bined Densal + solutionizing process. The bulk of the work pleted is included here as two papers to be submitted for publication. Each paper is a standalone work with separate abstract, introduction, procedure, results and discussion, conclusion and reference sections. The first paper included as Chapter 2 presents the experimental results of the process bination of Densal and solution heat treatment on several AlSiMg mercial castings. The second paper, Chapter 3, presents the results of the theoretical energy calculations of the bined process versus the individual processes of Densal f。