Understanding and Controlling Transformations in the HAZ of 3G AHSS

了解和控制 3G AHSS 的 HAZ 变换

• 批准号: 539602-2019
• 负责人: Biro, ElliotEJ
• 金额: $ 3.28万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760330
• 关键词: Understanding; Controlling; Transformations; HAZ; 3G

The Intergovernmental Panel on Climate Change reported that greenhouse gas (GHG) emissions must decrease to net-zero by 2055 to limit global warming to 1.5°C above pre-industrial levels. Automakers plan to decrease the GHG emissions of their vehicles by using ultra high strength steels (UHSS), with ultimate tensile strength (UTS) greater than 1 GPa, in their vehicles. UHSS allows thinner steels to be used for parts, reducing part weight, while retaining part strength. However, when UHSS are resistance spot welded (RSW), their complex composition and microstructure can lead to hardness peaks, softening, and liquid metal embrittlement (LME) cracks near the weld. These phenomena are not fully understood, but, it is known that thermal history will affect both weld hardness and LME.The proposed CRD project will better understand transformations and LME formation occurring during RSW of UHSS. This knowledge will be used to modify the RSW process to maximize joint performance and minimize LME cracking. To facilitate this, the weldability steels with UTS of 980 MPa and 1180 MPa. In-use steels with dual-phase (DP) microstructure and state-of-the-art Quench & Partition (QP) steels will be compared, enabling an understanding of how base material strength and microstructure affect transformations during welding and LME. The project will characterize transformations in the heat affected zone (HAZ) through changes in observed structures and mechanical properties. LME sensitivity in these steels will also be characterized. LME sensitivity will be mapped as with respect to welding parameters and in-situ observations of crack formation will be made. Understanding how thermal history affects HAZ transformations and LME will be used to optimize the welding process to maximize post-weld quality, informing a model to predict post-weld properties and cracking severity. These results will benefit Canada by increasing adoption of new UHSS steels into vehicles, creating a demand for Canadian steelmakers to make these high value steels, that will be used in Canadian automotive production.

政府间气候变化的面板报告说，到2055年，温室气体（GHG）的排放必须减少到净净数量，以将全球变暖限制为高于工业前水平的1.5°C。汽车制造商计划通过使用超高强度钢（UHSS）来减少车辆的温室气体排放，并在其车辆中使用大于1 GPA的最终拉伸强度（UTS）。 UHSS允许将较薄的钢用于零件，减轻零件的重量，同时保持零件强度。但是，当UHSS是电阻点焊接（RSW）时，它们的复杂组成和微观结构会导致硬度峰，软化和液态金属含量（LME）裂缝（LME）裂纹附近。这些现象尚未完全了解，但是，众所周知，热史将影响焊接硬度和LME。拟议的CRD项目将更好地理解UHSS RSW期间发生的转换和LME形成。这些知识将用于修改RSW过程，以最大程度地提高关节性能并最大程度地减少LME开裂。为了促进这一点，具有980 MPa和1180 MPa的UTS的焊接性钢。将比较具有双相（DP）微观结构和最新的淬灭与分区（QP）钢的钢钢，从而了解基础材料强度和微观结构如何影响焊接和LME期间的转换。该项目将通过观察到的结构和机械性能的变化来表征热影响区（HAZ）中的转化。这些钢中的LME灵敏度也将被表征。 LME灵敏度将与焊接参数一样映射，并将对裂纹形成的原位观察结果进行映射。了解热历史如何影响HAZ变换和LME将用于优化焊接过程以最大化焊接后质量，从而告知模型以预测焊接后特性和破裂的严重性。这些结果将通过增加新的UHSS钢的采用来使加拿大受益，从而对加拿大钢铁制造商制造这些高价值钢的需求，这些钢将用于加拿大汽车生产。