# Effect of Interlayers on Microstructure and Corrosion Resistance of 304/45 Stainless Steel Cladding Plate

## TL;DR

This study shows that adding NiP or NiCuP interlayers to stainless steel cladding plates reduces carbon diffusion and improves corrosion resistance, especially in the 304/NiCuP/45 specimen.

## Contribution

The novel use of NiCuP interlayers significantly enhances corrosion resistance by blocking carbon diffusion and forming a dense passive film.

## Key findings

- 304/45 specimens showed severe carbon diffusion and poor corrosion resistance.
- The 304/NiCuP/45 specimen had the lowest intergranular corrosion susceptibility (0.25%) and highest pitting potential (0.336 V).
- The 304/NiCuP/45 specimen formed the densest passive film with the lowest carrier density (3.02 × 10¹⁸ cm⁻³).

## Abstract

During the high-temperature preparation of stainless steel cladding plate, carbon atoms from carbon steel diffused into stainless steel. When temperatures were within 450–850 °C, carbides precipitated at grain boundaries, which initiated intergranular sensitization and thereby reduced the corrosion resistance of stainless steel. This study designed NiP and NiCuP interlayer alloys to effectively block carbon diffusion in stainless steel cladding plates. The effect of adding interlayers on the microstructure of stainless steel cladding plate was studied by using optical microscopy and scanning electron microscopy. Electrochemical tests were subsequently conducted to evaluate the impact of interlayer incorporation on the corrosion resistance of stainless steel cladding. The results demonstrated that 304/45 specimens exhibited severe carbon diffusion, resulting in the poorest corrosion resistance. The addition of interlayers improved the corrosion resistance of stainless steel cladding to varying degrees. Among these, the 304/NiCuP/45 specimen showed the best performance. It had an intergranular corrosion susceptibility of only 0.25% and pitting potential as high as 0.336 V, which indicated its superior corrosion resistance. The passive film of stainless steel cladding exhibited n-type semiconductor characteristics. And 304/NiCuP/45 specimen demonstrated the lowest carrier density of 3.02 × 1018 cm−3, which indicated the formation of the densest passive film.