The influence of thermal hardening on mechanical properties and microstructural evolutions of as-printed carbon steel

热硬化对印刷碳钢机械性能和微观结构演变的影响

• 批准号: 544439-2019
• 负责人: Nuño, Natalia
• 金额: $ 0.91万
• 依托单位: École de technologie supérieure
• 依托单位国家: 加拿大
• 项目类别: Engage Plus Grants Program
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=675290
• 关键词: influence; thermal; hardening; mechanical; properties

Additive Manufacturing (AM) is recent concept in fabrication to produce parts with different metallic materialssuch as steels, titanium alloys, superalloys, biocompatible metals as raw, semi-final, or final products for whichmaterial is added layer by layer instead of being formed by conventional shaping processes. In some industriessuch as biomaterials, aerospace, marine; technology readiness level (TRL) has gained enough to producecertified parts that could be competitive with their conventional versions as the process allows adapting eachpart to the specific need. However, the mechanical properties may not meet the expectations in service due tocomplex microstructure formed during AM processes.In the first step of the project, two different types of steels fabricated by two different process parameters werereceived. The main objective was to investigate the possible microstructural modification obtained fromchanging process parameters during printing. Using electron back scattered phase (EBSP) and localmisorientation maps, our first deliverable (2 first months - by end of January 2019) was to identify the strainheterogeneity formed during printing by interpreting data acquired from EBSD analysis. One of the sampleswas a stainless steel and the other one was a carbon steel.For the continuation of research work developed so far, it is necessary to get involved with mechanicalproperties. In this regard, initial hardness measurements were applied on carbon steels after thermal hardeningtreatment. This alloy is prioritized on request of our partner. It was found that changing process parametersduring printing affects the hardness value in carbon steel samples causing severe macro-cracking duringthermal hardening after printing. This confirms the literature talking about premature fracture for thermallyhardened carbon steels after printing [7]. Therefore, for the next step of our collaboration, it is necessary tocontinue the research work in a way to modify the thermal treatment required after printing in order to identifyoptimum thermal hardening process parameters according to the microstructure obtained during printing.

增材制造（AM）是制造中的最新概念，用于生产具有不同金属材料的部件，例如钢，钛合金，超级合金，生物相容性金属作为原材料，半成品或最终产品，其中材料逐层添加，而不是通过传统的成型工艺形成。在某些行业，如生物材料，航空航天，海洋;技术准备水平（TRL）已经获得了足够的生产认证的部分，可以与传统版本竞争，因为该过程允许调整每个部分的特定需求。然而，由于AM工艺过程中形成的复杂组织，其力学性能可能无法满足使用要求。主要目的是研究在印刷过程中改变工艺参数可能获得的微观结构修改。使用电子背散射相位（EBSP）和局部错误取向图，我们的第一个交付成果（前两个月-到2019年1月底）是通过解释从EBSD分析获得的数据来识别打印过程中形成的应变异质性。其中一个样品是不锈钢，另一个是碳钢。为了继续迄今为止的研究工作，有必要涉及机械性能。在这方面，初始硬度测量应用于热硬化处理后的碳钢。根据我们合作伙伴的要求，优先考虑这种合金。结果发现，印刷过程中改变工艺参数会影响碳钢样品的硬度值，导致印刷后热硬化过程中出现严重的宏观裂纹。这证实了文献中关于打印后热硬化碳钢过早断裂的讨论[7]。因此，对于我们合作的下一步，有必要继续研究工作，以修改印刷后所需的热处理，以便根据印刷过程中获得的微观结构确定最佳的热硬化工艺参数。