CLADDING TECHNOLOGY SHANXI CO., LTDStrengthening Technology of Cast Carbide Tungsten Iron-Based Composite Cladding Layer on Shoe Shoes
Literature Overview
This 2007 study published in Journal of Southwest Petroleum University (Natural Science Edition) by Liu Chengjie, Qiu Yaling, Song Zhenhua, Zhuang Jia, and Liu Qingyou from Southwest Petroleum University and Chengdu General Machinery Factory of Sichuan Petroleum Administration investigates the strengthening technology for cast tungsten carbide iron-based composite cladding layers on shoe shoes (shoe shoes or shoe shoes are drilling tools used in oil and gas well drilling operations). The research was supported by the Ministry of Education Key Laboratory project (JZTZ-0501) and addresses a critical challenge in the oil and gas drilling industry: extending the service life of shoe shoes through advanced surface engineering.
Shoe shoes are subjected to extreme operating conditions during drilling operations, including high temperatures (up to 250 °C at the bit face), high mechanical stress, abrasive contact with rock formations, and corrosive drilling fluids. The original shoe shoes typically have a service life of only 200-400 meters of drilling, leading to frequent replacement and significant operational costs.
Core Technical Content
Material Characterization
Base Material: Shoe Shoe Steel
| Property | Value |
|---|---|
| Carbon content | 0.8-1.2% |
| Manganese content | 0.5-1.0% |
| Chromium content | 0.5-1.0% |
| Molybdenum content | 0.2-0.5% |
| Hardness (as-supplied) | HV 500-600 |
| Tensile strength | 1200-1500 MPa |
| Impact toughness | 8-15 J/cm² |
| Thermal conductivity | 20-25 W/m·K |
Overlay Material: Tungsten Carbide Iron-Based Composite
| Property | Value |
|---|---|
| Tungsten carbide content | 20-40% (by volume) |
| Iron matrix | High-speed steel or martensitic stainless steel |
| Carbide particle size | 5-50 μm |
| Hardness (as-cast) | HV 800-1200 |
| Hardness (after heat treatment) | HV 1000-1500 |
| Wear resistance | 5-10x that of base material |
Casting and Cladding Process
The study investigates a combined casting and welding approach for applying tungsten carbide iron-based composite cladding layers on shoe shoes:
Process Steps:
- Base material preparation — Machining of shoe shoe to create a cavity or groove for the cladding layer
- Preheating — Heating the base material to 400-600 °C to reduce residual stress
- Powder packing — Filling the cavity with tungsten carbide iron-based composite powder
- Induction heating — Melting the surface of the base material to create a molten pool
- In-situ reaction — The molten pool reacts with the tungsten carbide particles, creating a metallurgical bond
- Solidification — Controlled cooling to achieve the desired microstructure
- Post-weld heat treatment — Tempering to optimize hardness and toughness
Microstructural Analysis
Overlay Layer Microstructure:
- Tungsten carbide (WC) particles dispersed in an iron-based matrix
- Matrix microstructure: martensite + tempered carbides
- WC particle distribution: relatively uniform with some clustering
- Carbide particle size: 5-50 μm (original) with some dissolution at the interface
- Bonding interface: metallurgical bond with a diffusion zone of 10-50 μm
Fusion Zone Microstructure:
- Mixed microstructure of martensite, tempered carbides, and dissolved WC
- Dilution rate: 15-30% (due to the casting process)
- Hardness: HV 900-1300
- Transition zone width: 0.5-2.0 mm
Heat-Affected Zone:
- Tempering of martensite in the base material
- Slight softening due to tempering
- HAZ width: 2.0-5.0 mm
Mechanical Properties
| Property | Base Material | Overlay Layer | Fusion Zone |
|---|---|---|---|
| Hardness (HV) | 500-600 | 1000-1500 | 900-1300 |
| Wear resistance (relative) | 1.0 | 5.0-10.0 | 4.0-8.0 |
| Impact toughness (J/cm²) | 8-15 | 3-6 | 5-10 |
| Compressive strength (MPa) | 2500-3000 | 4000-5000 | 3500-4500 |
Strengthening Mechanisms
The tungsten carbide iron-based composite cladding layer achieves its superior wear resistance through multiple strengthening mechanisms:
- Dispersion strengthening — Hard WC particles (HV 2000-2500) impede dislocation movement in the matrix
- Solid solution strengthening — Tungsten atoms dissolved in the iron matrix create lattice distortion
- Precipitation strengthening — Fine carbide precipitates (Mo₂C, WC) form during heat treatment
- Grain refinement — The casting process produces a fine-grained microstructure
- Work hardening — Plastic deformation during service increases hardness
Heat Treatment Optimization
The post-weld heat treatment is critical for optimizing the properties of the cladding layer:
| Treatment | Temperature | Time | Hardness (HV) | Toughness (J/cm²) |
|---|---|---|---|---|
| As-cast | — | — | 1000-1200 | 3-5 |
| Tempering at 500 °C | 500 °C | 2h | 950-1100 | 5-8 |
| Tempering at 600 °C | 600 °C | 2h | 900-1050 | 6-10 |
| Tempering at 700 °C | 700 °C | 2h | 850-1000 | 8-12 |
| H1000 treatment | 1000 °C | 1h | 1000-1200 | 4-7 |
The optimal heat treatment depends on the specific application requirements. For maximum wear resistance, the H1000 treatment is preferred. For a balance of wear resistance and toughness, tempering at 600 °C is recommended.
Defect Analysis and Countermeasures
| Defect | Cause | Countermeasure |
|---|---|---|
| Cracking at interface | Thermal stress, high cooling rate | Preheat base material, reduce cooling rate |
| Poor bonding | Insufficient melting, contamination | Increase preheat temperature, clean surfaces |
| Carbide dissolution | Excessive heat input | Control induction heating power and time |
| Carbide clustering | Poor powder mixing | Ensure uniform powder mixing |
| Porosity | Gas entrapment, moisture | Dry powder, ensure proper shielding |
| Spalling | Poor bonding, thermal stress | Optimize interface design, control cooling rate |
Engineering Applications
The tungsten carbide iron-based composite cladding on shoe shoes is suitable for the following applications:
| Application | Operating Conditions | Performance Benefits |
|---|---|---|
| Oil well drilling | Abrasive rock, high temperature | 3-5x life extension |
| Gas well drilling | Abrasive formation, high pressure | 3-5x life extension |
| Water well drilling | Abrasive sand, moderate temperature | 2-4x life extension |
| Geothermal drilling | High temperature, corrosive fluids | 3-6x life extension |
Study Insights and Reflections
This research demonstrates the effectiveness of tungsten carbide iron-based composite cladding for extending the service life of shoe shoes in oil and gas drilling operations. The key finding is that the composite cladding layer achieves a hardness of HV 1000-1500, which is 2-3 times higher than the base material, resulting in a 3-5 times improvement in service life.
The study also highlights the importance of the in-situ reaction between the molten pool and tungsten carbide particles in achieving a reliable metallurgical bond. This reaction creates a diffusion zone at the interface that enhances bonding strength and reduces the risk of spalling during service.
From an engineering practice perspective, the combined casting and welding approach offers a practical solution for applying high-performance cladding layers to complex geometries such as shoe shoes. The induction heating process provides localized heating that minimizes distortion of the base component, which is critical for maintaining the dimensional accuracy of shoe shoes.