The optimization of martensitic stainless steel composition to reduce hot tearing after laser powder bed fusion

• Published in: Materials & design 2022-11, Vol.223, p.111221, Article 111221
• Main Authors: Wu, Lingzhi, Zhang, Cong, Xu, Bin, Zhang, Liu, Yin, Haiqing, Zhang, Ruijie, Jiang, Xue, Wang, Yongwei, Su, Jie, Liu, Geng, Khan, Dil Faraz, Qu, Xuanhui
• Format: Article
• Language: English
• Subjects: Composition optimization; High throughput calculation; Hot tearing; Laser-based powder bed fusion; Martensitic stainless steel
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.111221

By calculating the crack susceptibility of different alloys, it is found that the Fe11Cr8Ni5Co3Mo martensitic stainless steel has the highest crack Solidification Cracking Susceptive index (SCS), which also means that it is the most susceptible to cracking. The alloy composition of Fe11Cr8Ni5Co3Mo martensitic stainless steel was optimised by expanding the range of elements in the national standard and by high throughput calculations, resulting in a reduction in the susceptibility to hot cracking from 6841 to 1861, and a significant reduction in cracking and a significant increase in all aspects of performance, as verified by selected laser melting experiments. [Display omitted] •Effective integration of thermodynamic calculations with the Python language to achieve high throughput calculations.•Combining the coefficient of solidification shrinkage with the Scheil phase diagram to consider Hot tearing sensitivity.•Based on the examination over an area of 105060 μm2, the total crack size was from 1231.84 μm to 648.02 μm. The area is reduced from 6861.85 μm2 to 2414.89 μm2.•The values of yield strength ranged from 644.7 MPa to 713.8 MPa, tensile strength increased from 884.24 MPa to 945.8 MPa, and elongation increased from 12.1 % to 13.9 % respectively. Ultra-high strength martensitic stainless steel plays an essential role in aerospace, nuclear and other fields. This paper addresses laser-based powder bed fusion of martensitic stainless steel, based on thermodynamic software and computer languages for high-throughput calculation in combination with the hot tear sensitivity index criterion, Optimization of the alloy composed of Fe11Cr8Ni5Co3Mo martensitic stainless steel for resistance to hot tearing. The martensitic stainless steel composition with the lowest crack sensitivity was selected from hundreds of millions of data sets, reducing the hot tearing sensitivity index from 6841 to 1861. The alloy with the lowest hot tearing sensitivity was Fe11.3Cr8.18Ni2.0Mo2.8Co0.24Mn0.02V0.02Si0.01C0.17Mg. The hot tearing sensitivity has been experimentally verified in conjunction with additive manufacturing, and a comparative study of the building state organization and mechanical properties has been made.