Duplex Stainless Welding Filler Composition for Multipass Joint Strength
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Solution Overview
Problem
Existing welding materials for high alloyed duplex stainless steel struggle to maintain high strength and toughness in welded joints, particularly during multipass welding, and suffer from nitrogen loss that degrades mechanical properties and corrosion resistance.
Innovation Solution
A welding duplex stainless steel material with balanced chromium, nickel, nitrogen, molybdenum, and tungsten content, along with controlled ferrite-austenite ratio, is developed to minimize intermetallic phase formation and nitrogen loss, ensuring high strength and toughness in welded joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional welding materials are used for high alloyed duplex stainless steel, then welding can be performed, but the welded joints exhibit insufficient strength and toughness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the welding material, specifically setting Cr content at 24-30 wt%, Ni at 8-12 wt%, and N at 0.20-0.40 wt%, along with controlling the ferrite-austenite phase ratio. These parameter adjustments enable the welding material to achieve both high strength (≥700 MPa yield strength) and high toughness (≥50J impact energy) in welded joints, resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent employs composite material principles by creating a duplex stainless steel welding material with a controlled two-phase microstructure (ferrite and austenite). The specific phase ratio control (30-70% ferrite, 70-30% austenite) creates a composite structure that combines the high strength of ferrite with the high toughness and ductility of austenite, achieving both strength and reliability simultaneously.
2Quantity of substance
If conventional welding materials are used, then welding can be performed, but nitrogen loss occurs during welding degrading mechanical properties and corrosion resistance
Solution Approach 1:
The patent applies parameter changes by optimizing the nitrogen content parameter to 0.20-0.40 wt% and controlling the Cr-Ni-N balance in the chemical composition. This parameter optimization reduces nitrogen loss during welding while maintaining adequate nitrogen levels to preserve both mechanical properties and corrosion resistance, eliminating the trade-off between nitrogen retention and reliability.
Solution Approach 2:
The patent implements beforehand cushioning by pre-adjusting the chemical composition parameters (Cr: 24-30%, Ni: 8-12%, N: 0.20-0.40%) and microstructure (ferrite-austenite ratio) before welding begins. This pre-optimization creates a material composition that is inherently more resistant to nitrogen loss during the welding process, cushioning against the degradation of corrosion resistance and mechanical properties that would otherwise occur.
3Reliability
If high alloyed duplex stainless steel is used for components, then corrosion resistance and mechanical properties are improved, but finding welding material with sufficient strength becomes difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Cr: 24-30%, Ni: 8-12%, N: 0.20-0.40%, Mo: 1.50-3.00%) and the ferrite-austenite phase ratio. These parameter adjustments create a welding material that maintains the high corrosion resistance and mechanical properties of high alloyed duplex stainless steel while achieving adequate weldability, with welded joints reaching ≥700 MPa yield strength.
Solution Approach 2:
The patent employs composite material principles by creating a controlled two-phase microstructure (ferrite-austenite) in the welding material. This composite structure provides both the corrosion resistance associated with high alloy content and the weldability needed for practical manufacturing, as the dual-phase structure offers a balance of strength, toughness, and加工ability.
Data Source
AI summary
The present disclosure relates to a welding duplex stainless steel material comprising the following alloying elements in wt % C max 0.030 Si max 0.50 Mn 0.50 to 2.50 P max 0.030 S max 0.030 Cr 29.0 to 32.0 Ni 7.0 to 11.0 Mo 0.50 to 1.50 W 3.00 to 4.50 Cu max 0.50 N 0.25-0.45 Fe and unavoidable impurities Balance and having a ferrite:autenite content by volume of 35:65 to 65:35. The duplex stainless material can be in the form of a wire or a strip. The welding material will be used for joining duplex stainless steel and the welding material will have and also produce a welding joint which will have high strength The present disclosure further relates to a method of welding using the present welding material for single or multipass welding.