Submerged Arc Welding Wire Composition for Hot Cracking Prevention
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Solution Overview
Problem
Submerged arc welding with high-Cr CSEF steel is prone to hot cracking due to high welding heat input, and existing methods either compromise creep strength or welding workability, with insufficient investigation into the interaction between wire and flux components.
Innovation Solution
A wire composition optimized for submerged arc welding, with controlled levels of C, Cr, Mo, V, Nb, N, and Ni, combined with a flux containing specific metal fluorides and carbonates, to prevent hot cracking while maintaining creep strength and toughness, by reducing low-melting-point compounds and stabilizing carbonitrides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high welding heat input is used for submerged arc welding with high-Cr CSEF steel, then welding efficiency is improved, but hot cracking occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the welding wire, specifically controlling C content at 0.03-0.12%, Cr at 8-13%, and adding specific amounts of Nb (0.01-0.15%) and V (0.03-0.40%) to modify the solidification characteristics and reduce hot cracking susceptibility while maintaining welding efficiency
Solution Approach 2:
The invention creates a composite alloy system in the welding wire that combines high-Cr CSEF steel base metal with microalloying elements (Nb, V) to achieve both high-temperature strength and improved crack resistance, effectively resolving the contradiction between welding efficiency and hot cracking resistance
2Reliability
If C content is reduced to prevent hot cracking, then hot cracking resistance is improved, but creep strength is lowered
Solution Approach 1:
The invention optimizes the C content within a specific range (0.03-0.12%) rather than simply reducing it, and compensates for creep strength by precisely controlling Cr (8-13%), Nb (0.01-0.15%), and V (0.03-0.40%) contents to ensure both hot cracking resistance and adequate creep strength are achieved
Solution Approach 2:
The invention develops a composite alloy system where multiple elements (Cr, Nb, V) work synergistically to provide both hot cracking resistance and creep strength, replacing the simplistic approach of merely reducing C content
3Strength
If wire composition is optimized for creep strength, then creep performance is improved, but welding workability deteriorates
Solution Approach 1:
The invention carefully balances multiple compositional parameters including C (0.03-0.12%), Si (0.03% or less), Mn (0.3-1.5%), Cr (8-13%), Nb (0.01-0.15%), V (0.03-0.40%), and N (0.01-0.08%) to achieve both excellent creep strength and superior welding workability, avoiding the trade-off between these properties
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 wire and flux combination achieves excellent creep performance, toughness, and welding workability, preventing hot cracking and ensuring stable carbonitride precipitation, even under long-term post-weld heat treatment.
Implementation Method 1
stabilizing carbonitrides
Data Source
Figure 1~2
Figure 3~4A
Figure 4B
AI summary
A wire for submerged arc welding used in combination with flux, wherein the wire contains, as components, a specific amount of each of C, Si, Mn, Cr, Mo, V, Nb and N and a specific amount or less of each of Ni, P, S, Cu, Al, B, and O, the total amount of Mn and Ni is 0.5-1.75% by mass, the ratio of Mn to S (Mn/S) is 87 or higher, and the remainder is Fe and inevitable impurities.