Zhuojin Pipe Fitting Co., LtdStudy Note on 3Cr13 Stainless Steel Overlay on Q235 Carbon Steel
Literature Overview
This paper by Wu Zhisheng, Yun Hui, Liu Cuirong, Li Ke, and Quan Wanglin from Taiyuan University of Science and Technology was published in Welding Technology in 2014 (Vol. 43, No. 3, pp. 13-15). Supported by Shanxi Provincial Science and Technology Project (20100321084), Taiyuan City Science and Technology Program (2011075), and Taiyuan University Innovation Fund (20121016), the study investigates the microstructure and hardness of 3Cr13 stainless steel overlay layers deposited on Q235 carbon steel plates using submerged arc welding.
Core Technical Findings
The study demonstrates that when the overlay layer count reaches three passes, the hardness of the overlay alloy becomes essentially independent of the base metal dilution rate. The average surface hardness of the three-pass overlay layer reaches HRC 45.9, with a microstructure consisting of needle-like martensite and retained austenite.
Multi-Pass Overlay Strategy
| Overlay Passes | Approximate Hardness (HRC) | Dilution Influence | Microstructure Character |
|---|---|---|---|
| 1 | Lower, significant dilution effect | High | Mixed structure with base metal influence |
| 2 | Intermediate | Moderate | Transitioning to martensitic |
| 3 | HRC 45.9 | Negligible | Needle martensite + retained austenite |
| 4+ | Marginal improvement | None | Stable martensitic structure |
Microstructural Analysis
The needle-like martensite structure formed in the 3Cr13 overlay is characteristic of the high carbon and chromium content combined with the rapid cooling rates typical of overlay welding. The retained austenite fraction provides beneficial toughness to the overlay layer, preventing the brittleness that would otherwise result from a fully martensitic microstructure. The three-pass approach effectively dilutes the influence of the Q235 base metal, ensuring that the overlay composition approaches the nominal 3Cr13 specification.
Practical Engineering Considerations
- For pipeline repair and hardfacing applications where carbon steel piping requires corrosion-resistant or wear-resistant surface layers, the three-pass minimum rule provides a reliable design criterion.
- Submerged arc welding offers excellent deposition rates and consistent quality for large-area overlay applications on pipe surfaces, making it suitable for pipeline repair operations.
- The HRC 45.9 hardness level provides adequate wear resistance for moderate abrasion environments while maintaining sufficient toughness for impact loading.
- Dilution control is critical: the first pass typically shows significant compositional deviation from the intended overlay alloy, and this must be accounted for in qualification testing.
Integration with Pipeline Engineering
In pipeline maintenance operations, carbon steel piping frequently requires localized overlay repair at erosion-prone locations such as elbows, tees, and pump discharge sections. This research provides a clear process guideline: three passes of 3Cr13 overlay by submerged arc welding achieves a stable, dilution-independent microstructure with adequate hardness. However, engineers must also consider the carbon content of the overlay and the risk of hydrogen-induced cracking in the heat-affected zone of the Q235 base metal, which may require preheating and post-weld heat treatment depending on the plate thickness and service conditions.