CLADDING TECHNOLOGY SHANXI CO., LTDCladding Repair of High-Manganese Wear-Resistant Steel Lining Plates
Overview and Background
High-manganese wear-resistant steel, commonly known as Hadfield steel (typically containing 11 to 14 percent manganese and 1 to 1.5 percent carbon), is widely used in applications subject to severe impact and abrasive wear, such as crusher liners, ball mill liners, and conveyor chutes. The unique property of Hadfield steel is its ability to work-harden dramatically under impact loading, transforming from a relatively soft austenitic structure (approximately 200 HV) to a very hard structure (exceeding 500 HV) through strain-induced martensitic transformation. However, when these lining plates are damaged or worn beyond acceptable limits, repair becomes challenging due to the inherent weldability issues of high-manganese steels. This study by Bi Dongxun and Yang Wenhui from Shanxi Guan Aluminum Co., Ltd. documents a successful cladding repair approach for high-manganese wear-resistant steel lining plates in an electrolytic aluminum production facility.
Weldability Challenges of High-Manganese Steel
High-manganese steels present several welding challenges that must be addressed in any repair or cladding operation. The primary challenges include:
- Hot cracking susceptibility: The wide austenite formation temperature range and the presence of low-melting-point eutectics at grain boundaries create a high susceptibility to hot cracking during solidification.
- Cold cracking: Although less severe than in high-carbon steels, cold cracking can occur in the heat-affected zone (HAZ) due to the formation of hard martensite during rapid cooling.
- Excessive hardness in HAZ: The rapid cooling rates typical of welding can cause martensitic transformation in the HAZ of high-manganese steel, leading to hardness values exceeding 600 HV and creating a brittle, crack-prone region.
- Weld shrinkage distortion: The high thermal conductivity of manganese and the large thermal expansion coefficient of the austenitic matrix contribute to significant welding distortion.
Welding Challenges and Countermeasures
| Challenge | Root Cause | Consequence | Countermeasure |
|---|---|---|---|
| Hot cracking | Low-melting-point eutectics, wide solidification range | Transverse cracks in weld metal | Use high-silicon consumables to eliminate eutectics |
| HAZ hardening | Rapid cooling, martensitic transformation | Brittle HAZ, reduced toughness | Preheat to 300-400°C, low heat input |
| Weld shrinkage | High thermal conductivity, large thermal expansion | Distortion, residual stresses | Backing bars, clamping, intermittent welding |
| Dilution issues | High manganese content dilutes filler metal | Loss of wear resistance in weld | Use high-carbon high-manganese filler |
| Residual stress | Thermal gradients, phase transformations | Stress cracking, distortion | Post-weld stress relief at 600-650°C |
Cladding Repair Approach
The researchers developed a cladding repair approach that involved depositing a wear-resistant overlay layer on the damaged areas of the lining plate rather than attempting to weld the high-manganese steel directly. This approach avoids the welding challenges associated with the base material by using a consumable that is compatible with the high-manganese steel while providing superior wear resistance.
Cladding Process Parameters
| Parameter | Value | Rationale |
|---|---|---|
| Consumable type | High-carbon high-manganese hardfacing wire (C-2.0%, Mn-20%) | Compatible with base metal, high hardness |
| Wire diameter | 4.0 mm | High deposition rate |
| Welding process | Submerged arc welding (SAW) | Deep penetration, high deposition rate |
| Flux type | Rutile-basic mixed flux | Good wettability, low hydrogen |
| Current | 500-600 A | DCEN polarity |
| Voltage | 30-35 V | Arc stability |
| Travel speed | 250-350 mm/min | Single pass |
| Preheat temperature | 300-400°C | Reduce HAZ hardness, prevent cracking |
| Interpass temperature | 300-400°C | Maintain thermal balance |
| Post-weld treatment | Stress relief at 600-650°C for 2 hours | Reduce residual stresses |
The cladding layer was deposited in two passes to achieve a total thickness of 3 to 4 mm above the original surface. The first pass served as a transition layer to ensure good metallurgical bonding with the base material, and the second pass provided the wear-resistant surface layer. The dilution between the base metal and the cladding layer was controlled at approximately 25 to 35 percent, which was sufficient to maintain a sound bond while preserving the wear-resistant properties of the overlay.
Microstructural Analysis of Cladding Layer
| Region | Microstructure | Hardness (HV) | Phase Composition |
|---|---|---|---|
| Base metal (Hadfield steel) | Austenite + minor martensite | 200-250 | Austenite ( |