Wear Behavior of Impact-Resistant Overlay Material TKCE50 Under Chipping Abrasion

Literature Overview

The study by Liu Zhengjun, Lu Dayong, Yin Yijun, Zeng Xiebo, and Wan Qian from Shenyang University of Technology, published in Journal of Shenyang University of Technology (Vol. 29, No. 1, 2007, pp. 28–31), investigates the wear behavior of a newly developed impact-resistant overlay electrode designated TKCE50. The research focuses on chipping-type impact abrasion, a severe wear mode encountered in mining equipment, earthmoving machinery, and material handling systems where components experience simultaneous impact loading and abrasive sliding.

Core Technical Content

Material Development and Characterization

The TKCE50 electrode was developed through systematic experimentation on weld composition and microstructure. The overlay metal is designed to exhibit high work-hardening capacity, enabling it to resist progressive material removal under cyclic impact-abrasion conditions. Comparative testing was conducted against the commercial D256 electrode, a well-established benchmark in the industry for impact-wear applications.

Test Parameter	TKCE50	D256
Overlay hardness (as-welded)	High	Moderate
Work-hardening rate	Excellent	Good
Chipping abrasion resistance	Superior	Reference
Welding processability	Good	Good

Impact-Abrasion Testing Methodology

Multiple impact abrasion tests were conducted to simulate the progressive wear conditions experienced in service. The test apparatus subjects the overlay surface to repeated impact events combined with sliding contact against abrasive particles, mimicking the chipping wear mechanism observed in bucket teeth, conveyor chutes, and crusher linings.

Hardness Evolution and Wear Mechanism

The key finding is that TKCE50 exhibits a significantly higher work-hardening rate than D256. Under repeated impact loading, the overlay microstructure undergoes progressive dislocation accumulation and strain-induced phase transformation, leading to substantial hardness increase. This strain-hardening mechanism provides a self-reinforcing wear resistance: as the surface is deformed by impact, it becomes harder, thereby resisting subsequent wear events more effectively.

Wear Mechanism Analysis

The study elucidates a three-stage wear progression:

Initial stage: Surface roughening occurs as abrasive particles indent the overlay surface. The microstructure at this stage is relatively equiaxed with moderate dislocation density.
Transition stage: Repeated impact causes localized plastic deformation, generating high dislocation densities and possibly martensitic transformation in susceptible microstructural regions. Hardness increases markedly.
Steady-state stage: A stable hardened layer forms on the surface, providing sustained resistance to further material removal. The wear rate stabilizes at a low value.

The chipping abrasion mechanism differs from pure abrasion or pure impact in that material removal occurs through the combined action of crack initiation at impact sites and crack propagation along sliding paths. The high work-hardening rate of TKCE50 delays crack initiation by increasing the critical stress required for crack nucleation.

Engineering Practice Integration

Application Selection Criteria

For engineers selecting overlay materials for impact-abrasion service, the following considerations apply:

Impact energy level: TKCE50 is particularly suited for applications where individual impact energies are moderate to high (e.g., rock crushers, hammer mills).
Temperature range: The work-hardening mechanism is temperature-dependent; above approximately 300°C, the effectiveness of strain hardening diminishes.
Corrosion environment: The study does not address corrosion-wear synergy; in corrosive-abrasive environments, additional alloying for corrosion resistance may be required.

Comparison with Conventional Approaches

Approach	Mechanism	Limitation
High-carbon martensitic overlay	Intrinsic hardness	Brittle, poor impact tolerance
Cermet overlay	Hard particle resistance	Poor adhesion under impact
TKCE50 work-hardening type	Strain-induced hardening	Limited effectiveness at elevated temperature
D256 (conventional)	Moderate hardening	Lower wear resistance than TKCE50

Critical Reflections

The paper's strength lies in its clear demonstration of the work-hardening mechanism as a viable strategy for impact-abrasion resistance. However, the study could benefit from quantitative wear rate data (e.g., volumetric wear loss in mm³/N·m) to enable direct comparison with other materials in a standardized framework. Additionally, the microstructural evolution during wear — specifically the role of retained austenite transformation and its contribution to hardening — deserves more detailed quantitative metallographic analysis.

Reference Value and Outlook

This work contributes to the design philosophy of overlay materials where toughness and wear resistance must coexist. The TKCE50 concept of leveraging work-hardening as the primary wear resistance mechanism offers an alternative to the traditional approach of relying solely on intrinsic microstructural hardness. For equipment manufacturers in mining and material handling, this material represents a potential upgrade path with extended service life. Future research should address the upper temperature limit of the work-hardening mechanism and the long-term durability under cyclic thermal-mechanical loading.