Stainless-Steel Welding Wire Composition for Cryogenic LNG Tank Joints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing welding materials for LNG tanks are limited in their application to specific types of structural steel, leading to confusion and economic disadvantages in the welding process, and they do not provide excellent cryogenic toughness.
Innovation Solution
A stainless-steel welding wire with a composition that includes 6.0 to 15.0 wt% Ni, 13.0 to 25.0 wt% Cr, 1.0 to 10.0 wt% Mn, 5.0 wt% or less Mo, and 0.05 to 1.0 wt% Si, which satisfies specific relational expressions to ensure excellent cryogenic toughness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional welding materials are used for different structural steels, then the strength and impact resistance requirements can be met, but the application is limited to specific materials and causes confusion and economic disadvantages
Solution Approach 1:
The patent develops a universal welding wire composition that can be applied to multiple types of structural steel (9% nickel steel, high manganese steel, and stainless steel) without requiring material-specific formulations. The controlled composition ranges of Ni (6.0-15.0 wt%), Cr (13.0-25.0 wt%), Mn (1.0-10.0 wt%), Mo (≤5.0 wt%), and Si (0.05-1.0 wt%) enable this wire to satisfy strength and impact resistance requirements across all three steel types, eliminating the need for multiple specialized welding materials and simplifying the work process
2Strength
If nickel content is increased to improve strength and toughness, then cryogenic performance improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the nickel content parameter to a specific range (6.0-15.0 wt%) that provides sufficient cryogenic toughness while controlling costs. Additionally, the patent balances nickel with other alloying elements (Cr: 13.0-25.0 wt%, Mn: 1.0-10.0 wt%, Mo: ≤5.0 wt%, Si: 0.05-1.0 wt%) and enforces the relational expression {Cr+Mo}/{Ni+Mn+30(C+N)}>1 to achieve cost-effective cryogenic performance through synergistic alloy interactions rather than relying solely on high nickel content
3Reliability
If alloy composition is optimized for excellent cryogenic toughness, then weld metal quality improves, but the composition becomes more complex to control
Solution Approach 1:
The patent defines specific composition ranges for each alloying element (Ni: 6.0-15.0 wt%, Cr: 13.0-25.0 wt%, Mn: 1.0-10.0 wt%, Mo: ≤5.0 wt%, Si: 0.05-1.0 wt%) and implements the relational expression {Cr+Mo}/{Ni+Mn+30(C+N)}>1 as a control criterion. These parameter specifications and the relational expression provide clear, quantifiable guidelines for composition control that balance cryogenic toughness requirements with manufacturing feasibility, avoiding overly complex control requirements
Data Source
AI summary
A stainless-steel welding wire for use in manufacture of an LNG tank is described. From the welding wire, it is possible to obtain a weld metal having excellent tensile strength and impact value because the contents of Ni, Mn, Mo, and Cr in the welding wire are adjusted. The welding wire can be applied to welding of all of 9% nickel steel, high manganese steel, and stainless-steel materials by adjusting the content relationship of Ni, Mn, Mo, and Cr, and has the effect of obtaining a weld metal with excellent ultra-low temperature toughness in the weld zone.