Metal Cored Wire Composition for Welding
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Solution Overview
Problem
Metal cored electrodes used in welding larger metal pipes face challenges in achieving a balance between high yield and tensile strengths and fracture toughness, particularly when forming weld beads in narrower grooves, which can result in cracking due to faster cooling rates and reduced impact properties.
Innovation Solution
A metal cored electrode with a unique composition including molybdenum, titanium, and boron, along with other alloying elements like aluminum, carbon, chromium, copper, manganese, nickel, and silicon, is developed to enhance the weld metal's yield and tensile strengths while improving notch toughness, specifically designed for use in electric arc welding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If weld beads are formed in narrower grooves with lower heat input, then welding productivity increases and welding time decreases, but the cooling rate increases causing reduced fracture toughness and increased risk of cracking
Solution Approach 1:
The invention changes the chemical composition parameters of the weld metal by incorporating specific amounts of microalloying elements (titanium: 0.005-0.050%, boron: 0.0005-0.0050%, molybdenum: 0.05-1.50%) to achieve the desired balance between strength and toughness. This compositional parameter change allows the weld metal to maintain adequate toughness even under faster cooling conditions
Solution Approach 2:
The invention creates a composite weld metal composition that combines multiple alloying elements (microalloying elements including titanium, boron, and molybdenum) with base metals (carbon steel, low alloy steel, or stainless steel). This composite material approach leverages the synergistic effects of different elements to achieve both high strength and adequate toughness
2Strength
If the weld metal is designed for high yield and tensile strength, then structural integrity improves, but the impact properties and fracture toughness may be reduced
Solution Approach 1:
The invention optimizes the concentration parameters of microalloying elements to achieve a balance between strength and toughness. Specifically, titanium (0.005-0.050%) and boron (0.0005-0.0050%) are controlled at low levels to prevent excessive hardening that would reduce toughness, while molybdenum (0.05-1.50%) is used to enhance both strength and tempering resistance, achieving a balanced property profile
Solution Approach 2:
The invention applies local quality by using microalloying elements that provide localized strengthening mechanisms (precipitation hardening, grain refinement) without uniformly increasing the overall hardness and brittleness of the weld metal. This allows high strength in critical areas while maintaining adequate toughness in the bulk material
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 electrode produces weld beads with increased yield strengths, tensile strengths, and notch toughness, maintaining these properties even at faster cooling rates, effectively addressing the issue of cracking and enhancing the integrity of welded joints.
Implementation Method 1
The weld metal formed from the metal cored electrode of the present invention includes at least about 0.04 weight percent molybdenum; at least about 0.0002 weight percent boron; at least about 0.001 weight percent titanium and a majority weight percent iron
Implementation Method 2
The weld metal formed by the metal cored electrode of the present invention has improved notch toughness and yield strength
Implementation Method 3
The metal cored electrode according to the invention forms a weld metal on a workpiece having increased yield and tensile strength characteristics. The electrode and weld metal is useful in welding pipe joints
Data Source
AI summary
A metal cored electrode used to form a weld metal on a workpiece having improved yield strength, tensile strength and impact toughness.