ERW Clad Steel Pipe Weld Geometry to Prevent Base Metal Exposure
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Solution Overview
Problem
Conventional methods for producing electric resistance welded clad steel pipes or tubes face challenges in reducing weld width to suppress property degradation and preventing base metal exposure, which impairs corrosion resistance and mechanical properties.
Innovation Solution
The method involves indenting both transverse ends of a clad steel strip to form a specific Y-groove shape before welding and using shielding gas to reduce oxygen concentration, thereby preventing base metal exposure and minimizing solidification microstructure in the weld area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of upset by squeeze rolls is increased to discharge oxidized melts and prevent penetrators, then weld quality improves, but base metal is exposed at the cladding metal-side surface causing decreased corrosion resistance
Solution Approach 1:
The patent applies preliminary action by forming a groove (bevel) at the transverse ends of the clad steel strip before welding. This groove has a specific shape with the clad interface turning from the cladding metal side toward the thickness center, creating a geometric structure that prevents base metal exposure during welding while maintaining weld quality. The groove is formed in advance so that when upset occurs during welding, the base metal remains covered by cladding metal at the inner surface.
Solution Approach 2:
The patent applies parameter changes by specifying precise geometric parameters of the groove: bevel angle θ1 on the cladding metal side is 10° to 50°, groove depth d1 is 10% to 45% of total thickness, and projection clad ratio R1 is 25% to 50%. These parameter changes create optimal conditions where the groove shape controls metal flow during welding, preventing base metal exposure while ensuring proper weld quality without requiring excessive upset.
2Object-affected harmful factors
If post-treatment such as weld overlaying or melting and solidification is performed to prevent base metal exposure, then corrosion resistance improves, but manufacturing complexity and productivity decrease
Solution Approach 1:
The patent eliminates the need for post-treatment by applying preliminary action - forming the groove structure before welding. This pre-formed groove geometry inherently prevents base metal exposure during the welding process itself, making subsequent overlaying or melting operations unnecessary. The solution is built into the pre-weld preparation stage rather than requiring additional post-weld steps.
Solution Approach 2:
The patent applies taking out by removing the need for complex post-treatment processes (weld overlaying, melting and solidification) that were previously required. By using the groove shape to prevent base metal exposure inherently, the patent extracts or eliminates these additional manufacturing steps, simplifying the overall process while maintaining corrosion resistance.
3Strength
If the weld width is reduced to suppress property degradation, then mechanical properties improve, but preventing base metal exposure becomes more difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the groove geometry parameters (bevel angle 10°-50%, groove depth 10%-45% of thickness, projection clad ratio 25%-50%) to achieve a balance where weld width is minimized for improved mechanical properties while the groove shape simultaneously ensures base metal coverage. The specific parameter ranges create optimal metal flow characteristics during welding.
Solution Approach 2:
The patent applies local quality by creating a localized groove structure at the weld zone with specific geometric properties. The groove shape concentrates the prevention function at the critical weld area where base metal exposure would occur, while the rest of the cladding metal maintains its protective function. The local geometric modification at the groove region enables both narrow weld and base metal coverage.
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 results in an electric resistance welded clad steel pipe or tube with improved corrosion resistance and mechanical properties, specifically enhanced toughness, without the need for post-treatment such as weld overlaying or melting and solidification.
Implementation Method 1
butt pressing and welding both transverse ends of the steel strip heated and molten by high-frequency current
Implementation Method 2
using shielding gas to reduce oxygen concentration, thereby preventing base metal exposure
Data Source
AI summary
Provided is an electric resistance welded clad steel pipe or tube in which a region where solidification microstructure is formed, i.e. a region in a weld particularly having significant influence on properties, is reduced without impairing its function as a clad pipe or tube. An electric resistance welded clad steel pipe or tube comprises: a first layer made of carbon steel or low-alloy steel as base metal; and a second layer placed on one surface of the first layer, and made of stainless steel or a nickel-containing alloy as cladding metal, wherein the base metal is not exposed at a cladding metal-side surface of the electric resistance welded clad steel pipe or tube in a weld, and no solidification microstructure is contained in each of circular sections of 0.1 mm in radius respectively centered at specific three positions in a plane perpendicular to a pipe or tube longitudinal direction.