Influence of heat input on bead geometry, microstructure and hardness characteristics of dissimilar 410 martensitic stainless steel weld deposits on 304L substrate

Abstract

ABSTRACT Examining the impact of heat-input (QHI) on the characteristics of dissimilar welds of 410 and 304L is essential for improving the structural integrity, longevity, and functionality of bimetallic welds and components produced through additive manufacturing. The study delved into key variables influencing deposited bead and fusion zone (FZ) characteristics. An increase in QHI from 170J/mm to 530J/mm caused an exponential bead width (W) rise, expanding the weld bead width from 5mm to 13mm. Despite this, both bead height and penetration depth rose, resulting in a reduction of aspect ratios at higher QHI values. Aspect ratios remained low within the range of 300-480J/mm. Furthermore, the research demonstrated that an increased QHI value caused a reduction in the Cr-Ni equivalent ratio from 1.91 to 1.77, promoting the γ-phase in the FZ. The γ-phase further transformed into α’-martensite upon cooling. The lowest QHI increased the γ-phase metastability, fostering the formation of α’ and γ-FeNi in the FZs, gradually elevating the deposition hardness up to 13.9 % compared to the highest QHI. Various linear and non-linear models were developed to anticipate the correlations for predicting crucial parameters such as Ms temperature, Mεs temperature, SFE, α’-martensite volume fraction, γ-FeNi volume fraction, and hardness.