Electroslag Welding Wire Composition for 9% Ni Steel Joints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing welding methods for 9% Ni steel, such as coated arc welding and TIG welding, result in weld metals with lower strength and cryogenic toughness compared to the base metal, necessitating thicker designs and higher heat input, while also posing challenges in working environment and mechanical performance.
Innovation Solution
Development of an electroslag welding wire and flux combination with specific chemical compositions, including 6.0-15.0% Ni, C, Si, Mn, and Fe, along with optional elements like Cu, Cr, Mo, W, Nb, V, and B, and a slag forming agent, to achieve high heat input welding with improved mechanical properties and reduced atmospheric interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding methods (coated arc welding, TIG welding) are used for 9% Ni steel, then cryogenic toughness is improved, but strength decreases and design plate thickness must be increased
Solution Approach 1:
The invention changes the chemical composition parameters of the weld material by specifying precise ranges for C (0.005-0.10%), Si (0.01-0.50%), Mn (0.01-1.00%), Ni (6.0-15.0%), and other alloying elements, along with their interactions (e.g., Ni×C≥0.006, (Ni+Cr+Mo)×C≥0.008). These parameter changes enable the weld metal to simultaneously achieve high strength and excellent cryogenic toughness, resolving the contradiction between strength and reliability.
2Reliability
If conventional welding methods are used, then cryogenic toughness is maintained, but heat input increases and working environment deteriorates
Solution Approach 1:
The invention replaces conventional arc welding methods with electroslag welding, substituting the arc heating mechanism with resistive heating through molten flux. This substitution reduces heat input (to 10 kJ/mm or more, which is lower than conventional methods for achieving similar results) and improves working conditions by eliminating arc radiation and spatter, while the controlled composition ensures cryogenic toughness is maintained.
3Reliability
If Ni-based weld material is used to improve cryogenic toughness, then toughness is enhanced, but strength decreases and productivity is reduced
Solution Approach 1:
The invention optimizes the Ni content parameter to 6.0-15.0% and establishes specific interaction parameters (Ni×C≥0.006, (Ni+Cr+Mo)×C≥0.008) that enable lower Ni usage compared to conventional Ni-based weld materials. This parameter optimization achieves the required cryogenic toughness while reducing material cost and improving welding productivity through the electroslag process.
4Use of energy by moving object
If electroslag welding is used to reduce heat input, then energy efficiency is improved, but achieving high strength and toughness simultaneously becomes difficult
Solution Approach 1:
The invention creates a composite chemical composition system combining multiple alloying elements (C, Si, Mn, Ni, Cr, Mo, B, etc.) with specific interaction relationships. This composite material approach, applied to the electroslag welding process, enables the weld metal to achieve high strength (comparable to base metal) and excellent toughness simultaneously, while maintaining the energy efficiency benefits of electroslag welding with controlled heat input of 10 kJ/mm or more.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables weld joints with enhanced strength and cryogenic toughness, even at high heat inputs of 10 kJ/mm or more, improving working conditions and mechanical performance by reducing arc radiation and spatter, and eliminating the need for shielding gas.
Implementation Method 1
electroslag welding
Implementation Method 2
a molten flux barrier that shields the weld pool from atmospheric contamination, eliminating the need for external shielding gas
Implementation Method 3
reduces heat input and improves energy efficiency compared to conventional arc welding methods
Data Source
Figure 1
AI summary
The present invention relates to a wire for electroslag welding, which is characterized by containing, in mass% relative to the total mass of the wire, more than 0% but 0.07% or less of C, more than 0% but 0.50% or less of Si, more than 0% but 1.0% or less of Mn, from 6.0% to 15.0% of Ni and 79% or more of Fe, while satisfying formula (1). The present invention also relates to: a flux for electroslag welding, which is used in electroslag welding together with the wire for electroslag welding; and a welded joint which is produced by electroslag welding that uses the wire for electroslag welding and the flux for electroslag welding. 0.150 ≤ C + Si/30 + Mn/20 + Ni/60 ≤ 0.300 (1)