Gas-Shielded Arc Welding Nozzle Geometry and Sulfur Additive

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Solution Overview

Problem

Existing gas-shielded arc welding methods fail to effectively suppress oxidation reactions on weld bead surfaces and convex bead shape formation due to atmospheric air entrainment, particularly during high-speed welding, as the shielding region is limited by small-diameter nozzles and does not account for high-temperature reactions.

Innovation Solution

A gas-shielded arc welding method using a nozzle with an inner diameter of 15 mm or more and a nozzle-base material distance of 22 mm or less, combined with a shielding gas flow rate of 18 L/min or less and a consumable electrode containing 0.015% sulfur, which preferentially adsorbs on molten pool surfaces to suppress oxidation reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a small-diameter nozzle is used to improve gas flow control, then gas flow uniformity is improved, but the shielding region is limited and oxidation reaction suppression is insufficient

Engineering Contradiction:

Improvegas flow uniformityVSAvoidshielding region

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The patent changes the key parameter of nozzle inner diameter from conventional small sizes to 15mm or more, fundamentally altering the shielding gas flow characteristics and expanding the shielding region to effectively cover high-temperature molten metal areas during high-speed welding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a new dimensional relationship by specifying the ratio of nozzle inner diameter to nozzle-to-base-material distance (0.7-1.9), creating an optimized spatial configuration that expands shielding coverage while maintaining flow control

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If a small-diameter nozzle is used to improve gas flow control, then gas flow uniformity is improved, but oxidation reaction suppression on molten metal is insufficient

Engineering Contradiction:

Improvegas flow uniformityVSAvoidoxidation reaction

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful oxidation reaction into a beneficial process by adding sulfur (0.01-0.05 mass%) to the consumable electrode, which reacts with oxygen to form sulfur oxides that protect the weld metal from oxidation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If atmospheric air shielding is increased to suppress oxidation, then oxidation suppression is improved, but nitrogen entrainment increases causing pits or blow holes

Engineering Contradiction:

Improveoxidation suppressionVSAvoidnitrogen entrainment

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent applies different protective mechanisms to different harmful elements: using physical shielding gas expansion for oxygen suppression and chemical deoxidization with sulfur for nitrogen management, allowing selective control of different harmful factors

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful nitrogen entrainment into a manageable process by adding sulfur to the consumable electrode, which forms nitrides and prevents nitrogen from causing pits or blow holes

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach effectively reduces the entrainment of atmospheric air, minimizing the formation of blow holes, convex bead shapes, and excessive slag on weld surfaces by maintaining low oxygen and nitrogen levels in the molten metal and enhancing the shielding effect.

Implementation Method 1

General role of a shielding gas in a gas-shielded arc welding is to shield arc, a molten metal and a consumable electrode from the atmospheric air and prevent a welded part from nitration and oxidation

Methodology Applied

Scientific EffectShielding gas effect:

Implementation Method 2

consumable electrode containing 0.015% sulfur, which preferentially adsorbs on molten pool surfaces to suppress oxidation reactions

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

gas-shielded arc welding method

Methodology Applied

Scientific EffectElectric arc heating: Electric Arc

Implementation Method 4

performing welding while flowing a shielding gas

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10864594B2Gas-shielded arc welding method

Publication Date: 2020.12.15 KOBE STEEL LTD

AI summary

A gas-shielded arc welding method includes feeding a consumable electrode via a welding torch and performing welding while flowing a shielding gas. The welding torch includes a nozzle. An inner diameter of the nozzle is 15 mm or more. A nozzle-base material distance between a tip of the nozzle and a material to be welded is 22 mm or less. A ratio expressed by (the inner diameter of the nozzle/the nozzle-base material distance) is 0.7 or more and 1.9 or less.