Piercing Plug Ni-Cr Alloy Arc-Sprayed Coating Erosion Resistance
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Solution Overview
Problem
Piercing plugs used in the Mannesmann process for manufacturing seamless steel pipes face high deformation and erosion due to contact with heated billets, reducing their usage count and lifespan, especially when made from Fe-based alloys without oxidized scales or adequate coatings.
Innovation Solution
A piercing plug with a Ni—Cr-based alloy plug body, a Ni—Cr layer, and a sprayed coating formed on the surface, where the Ni—Cr layer acts as an adhesive enhancing the shear strength and wear resistance of the coating, and the coating is preferably made from iron and iron oxide, formed by arc-spraying, to prevent deformation and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a Ni—Cr-based alloy is used as the base material of the piercing plug to suppress deformation, then deformation resistance is improved, but the sprayed coating is likely to be peeled off and the lifespan is reduced
Solution Approach 1:
The invention uses a composite material structure consisting of a Ni—Cr-based alloy base material combined with a specific sprayed coating system. The base material contains 20-30% Cr, 30-55% Ni, and specific amounts of C, Si, Mn, Mo, and W to achieve both high deformation resistance and good coating adhesion. This composite approach allows the piercing plug to simultaneously achieve improved strength and extended lifespan.
2Temperature
If the oxidized scale is removed from the surface of the piercing plug, then the temperature of the base material is increased improving heat transfer, but the piercing plug is eroded
Solution Approach 1:
The invention changes the surface condition parameter by applying a sprayed coating instead of relying on oxidized scale. The sprayed coating provides a controlled surface layer that allows appropriate heat transfer while protecting against erosion. The coating acts as a protective barrier that manages the thermal and mechanical interactions between the plug and the billet.
3Object-affected harmful factors
If a sprayed coating is formed on the surface of the base material to prevent erosion, then erosion resistance is improved, but the coating is likely to be peeled off when using Ni—Cr-based alloy
Solution Approach 1:
The invention applies local quality by creating a specific chemical composition gradient in the base material surface layer. The base material contains controlled amounts of Cr (20-30%) and Ni (30-55%) with specific alloying elements (C: 0.005-0.5%, Si: 0.1-1.0%, Mn: 0.2-1.5%, Mo: 0.05-7.0%, W: 0.05-3.0%) that create a surface layer with improved coating adhesion properties while maintaining bulk deformation resistance.
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 provides enhanced deformation resistance and adhesion of the coating, significantly increasing the lifespan and usage count of the piercing plug by suppressing erosion and seizure, while maintaining the ability to manufacture hollow tube stocks of the same size.
Implementation Method 1
a Ni—Cr layer formed on a surface of the plug body... the Ni—Cr layer acts as an adhesive enhancing the shear strength and wear resistance of the coating
Implementation Method 2
a sprayed coating formed on a surface of the Ni—Cr layer... preferably made from iron and iron oxide, formed by arc-spraying
Implementation Method 3
suppressing erosion and seizure... enhanced deformation resistance and adhesion of the coating, significantly increasing the lifespan and usage count
Data Source
AI summary
A piercing plug of the present invention includes: a plug body; a Ni—Cr layer formed on a surface of the plug body; and a sprayed coating formed on a surface of the Ni—Cr layer. The plug body contains, by mass %, 20 to 30% of Cr, 30 to 55% of Ni, 0.005 to 0.5% of C, 0.1 to 1.0% of Si, 0.2 to 1.5% of Mn, and at least one of Mo and W which satisfy a following conditional expression (A), and remainder including Fe and impurities.1.5%≤Mo+0.5W≤8.5% (A)