Abstract Cr-alloyed PM steels attract great interest in industry, especially in the automotive industry, because, due to the mechanical requirements for the parts, the parts are often subjected to hardening thermal treatments after sintering. In the present work, a sinter-hardening process was carried out in a single stage for pieces based on PM Astaloy CrA steel using concentrated solar energy. The influence of the sintering cycle and atmosphere used, as well as the content of the alloy, were studied. Among the main results obtained, it has been demonstrated that alloys based on Astaloy CrA have been successfully sintered using solar energy. Almost complete densities have been achieved, but these densities are not achieved by conventional techniques, and much shorter sintering times and temperatures (∼ 15 min of holding time at 1070 ± 10 °C) are required compared to those used in the usual processing techniques. In addition, the use of concentrated solar energy in metal treatment leads to high heating and cooling speeds that have encouraged the sinter-hardening process through the formation of bainitic and martensitic phases, which are characterized by being harder and more resistant than ferritic and pearlitic phases. Homogeneous microstructures have been obtained without the need to apply subsequent heat treatments such as tempering that it uses in the processed by conventional techniques. This research work is also intended to promote the use of concentrated solar energy in metallurgical processes that require high temperatures because it is a cheap, nonpolluting and renewable technology. Additionally, high heating and cooling speeds that often result in an improvement of the final properties of the pieces can be obtained without the need to use any external cooling medium.

中文翻译：

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使用集中太阳能对铬 PM 钢进行烧结硬化

摘要 铬合金粉末冶金钢引起了工业特别是汽车工业的极大兴趣，因为由于零件的机械要求，零件在烧结后经常进行硬化热处理。在目前的工作中，使用聚光太阳能对基于 PM Astaloy CrA 钢的工件进行单一阶段的烧结硬化过程。研究了所使用的烧结周期和气氛以及合金含量的影响。在获得的主要结果中，已经证明基于 Astaloy CrA 的合金已成功地使用太阳能进行烧结。已经达到了几乎完全的密度，但这些密度是传统技术无法达到的，与通常的加工技术相比，需要更短的烧结时间和温度（在 1070 ± 10 °C 下保持约 15 分钟的时间）。此外，在金属处理中使用聚光太阳能导致高加热和冷却速度，通过形成贝氏体和马氏体相促进烧结硬化过程，这些相的特点是比铁素体和珠光体相更硬、更耐腐蚀. 已获得均匀的微观结构，而无需应用后续热处理，例如在通过常规技术加工时使用的回火。这项研究工作还旨在促进聚光太阳能在需要高温的冶金过程中的使用，因为它是一种廉价、无污染和可再生的技术。