Application of a Novel Nickel-Based Superalloy Overlay Welding Electrode on Fixed-Width Press Modules

Literature Overview

This topic, authored by Wang Guanghuan (Shanghai Jiao Tong University), Jiang Guangbiao (Baosteel Hot Rolling Plant), and Jiang Guangjian (Baosteel Equipment Maintenance Co., Ltd.), published in 2009, addresses the application of a novel nickel-based superalloy overlay welding electrode on fixed-width press modules in hot rolling mill service. The collaboration between an academic institution, a major steel producer, and an equipment maintenance company reflects the practical, industry-driven nature of this research. Fixed-width press modules are critical components in hot strip mills, subjected to extreme thermal cycling, mechanical loading, and abrasive wear from scale and hot metal contact.

Service Environment and Failure Analysis

Fixed-width press modules in hot rolling mills operate under the following severe conditions:

Temperature: Surface temperatures can reach 600 °C to 800 °C during rolling operations
Mechanical loading: Contact pressures of 500 MPa to 1500 MPa during rolling passes
Thermal cycling: Rapid heating and cooling cycles during continuous rolling operations
Abrasive wear: Contact with hot scale (iron oxide) and mill scale fragments
Oxidation: Exposure to reducing and oxidizing atmospheres in the rolling mill

The typical failure modes of unclad press modules include:

Failure Mode	Mechanism	Typical Location
Surface abrasion	Scale and hot metal abrasion	Working faces
Thermal fatigue cracking	Thermal cycling stress	Surface and subsurface
Galling and seizure	Adhesive wear under high contact pressure	Contact surfaces
Oxidation scaling	High-temperature oxidation	Exposed surfaces
Plastic deformation	Overload under elevated temperature	Load-bearing areas

Nickel-Based Superalloy Overlay Electrode Selection

The selection of nickel-based superalloy overlay electrodes for this application is driven by the following material properties:

High-temperature strength: Nickel-based alloys retain significant strength at temperatures up to 800 °C to 1000 °C
Oxidation resistance: Chromium and aluminum additions form protective oxide scales
Thermal shock resistance: Low thermal expansion coefficient and high toughness
Galling resistance: Nickel-based alloys exhibit low adhesion to steel substrates

Common nickel-based superalloy overlay electrode compositions include:

Electrode Type	Ni (%)	Cr (%)	Mo (%)	Fe (%)	Key Characteristics
Ni-Cr-Mo type	55-65	20-30	5-10	Bal.	High-temperature strength, oxidation resistance
Ni-Fe-Cr-Mo type	30-45	15-25	3-8	25-40	Good weldability, moderate high-T strength
Ni-Cr-W-Mo type	50-60	15-25	5-10	Bal.	Enhanced thermal fatigue resistance

Overlay Process and Quality Control

The overlay welding process for fixed-width press modules typically follows these steps:

Surface preparation: Grinding or shot blasting to remove oxidation and contamination; ensuring a clean, sound base surface
Preheat: Application of 200 °C to 300 °C preheat to reduce cracking susceptibility in the base material
Overlay welding: Multiple passes of the nickel-based superalloy electrode, typically using SMAW or FCAW processes
Post-weld treatment: Controlled cooling or post-weld heat treatment to relieve residual stresses
Machining: Precision machining to achieve final dimensional tolerances
Inspection: Non-destructive testing (MT or PT) to verify overlay integrity

FMEA Analysis of Overlay Process

Process Step	Potential Failure	Effect	Severity	Detection Method	Countermeasure
Surface prep	Incomplete cleaning	Poor bond, overlay spalling	High	Visual + MT	Implement strict cleaning protocol
Preheat	Insufficient preheat	Cracking in base metal	High	UT/MT	Use calibrated preheat equipment
Welding	Excessive dilution	Loss of overlay properties	Medium	Hardness test, XRF	Control travel speed and electrode angle
Post-weld	Rapid cooling	Residual stress, cracking	High	MT/PT	Implement controlled cooling
Machining	Inadequate depth	Insufficient overlay remaining	Medium	Thickness measurement	Allow adequate machining allowance

Engineering Practice and Performance Results

In hot rolling mill applications, the application of nickel-based superalloy overlay electrodes on fixed-width press modules has demonstrated significant improvements in service life. Typical performance improvements include:

Service life extension: 2 to 5 times the life of unclad modules
Surface hardness: 350 HV to 500 HV after overlay (compared to 200 HV to 250 HV for base material)
Thermal fatigue resistance: Improved crack resistance under thermal cycling
Oxidation resistance: Reduced scale formation at elevated temperatures

The key to successful application lies in matching the overlay electrode composition to the specific service conditions. For example, modules operating at higher temperatures may require higher chromium and aluminum content for enhanced oxidation resistance, while modules subjected to higher mechanical loads may benefit from higher molybdenum content for improved creep resistance.

Study Insights

The collaboration between academia, industry, and maintenance services in this study exemplifies the effective pathway for translating research into industrial practice. The development of a novel nickel-based superalloy overlay electrode specifically tailored for hot rolling mill press modules demonstrates that purpose-designed consumables can significantly outperform generic overlay solutions. Engineers should note that the success of overlay applications in high-temperature, high-stress environments depends not only on the overlay material properties but also on careful process control, proper joint design, and comprehensive quality assurance.