Research & Development
G410
Alloy Description:
Grade G410+ is a carbon/manganese steel with and excellent combination of strength and ductility suitable for low temperature application and is a product of Goodwin’s internal material development. The material is supplied in the quench and tempered condition to ensure optimal through section mechanical strength and has controlled CE and PCM, which ensures excellent weldability.
With 6A-G material, sigma phase precipitation can be eliminated or significantly reduced leading to dramatic improvements in both low temperature impact properties and pitting corrosion resistance, with no reduction in through section tensile strength.
Application:
Used for casting applications where a yield strength of >410N/mm2 is required, with superior low temperature impact strength, and exceptional weldability characteristics.
| Element | Symbol | Typical |
|---|---|---|
| Carbon | C | 0.12 |
| Silicon | Si | 0.30 |
| Manganese | Mn | 1.50 |
| Sulphur | S | <0.005 |
| Phosphorus | P | <0.010 |
| Nickel | Ni | <0.75 |
| Chromium | Cr | 0.20 |
| Molybdenum | Mo | 0.10 |
Melting Route:
Grade 410+ is produced by electric arc or induction primary melting, followed by secondary AOD refinement. The AOD refinement has major chemistry benefits with regards to ultra low sulphur and deleterious residual elements, along with low residual nitrogen and hydrogen gas content. By reducing these elements enhanced mechanical properties are obtained.
Carbon Equivalent (CE) and Parameter Crack Measurement (PCM):
| Process | Unit | Max |
|---|---|---|
| Carbon Equivalent | (%) | 0.48 |
| Parameter Crack Measurement | (%) | 0.28* |
*when not specified is taken as a target maximum
Grain Size:
Table 5: Typical cast grain size
| Grain Size (ASTM E112) |
|---|
| Section size =100mm to 360mm |
| Range 12 (or finer) to 7.5 |
Fig 1:Typical Microstructure , 50mm
Cleanliness to ASTM E45 Method A, specimen polished to 1 micron and examined unetched. Type A – Thin – 1/2, Type D – Thin 1.
Mag X500:
Showing fine tempered acicular ferrite and pearlite
Heat Treatment Requirements:
Table 3: Typical Heat Treatment Cycle
| Process | Unit | Max |
|---|---|---|
| Homogenisation | °C | 930 |
| Austenitise +Quench | °C | 930 |
| Quench Media | Recirculated Water | |
| Temper | °C | 610 – 680 |
Typical Mechanical Properties:
Tempering performed at 610°C
Table 4: Typical Centre Section Properties
| Section size ≤50mm (t=1/2) | ||
|---|---|---|
| Property | Unit | Typical |
| Tensile Strength | N/mm2 | 600 |
| Yield (0.2% proof) | N/mm2 | 460 |
| Elongation | % | 25 |
| Reduction in Area | % | 72 |
| Avg Impact Strength | J | 105 |
| Section size = 100mm (t=1/2) | ||
| Property | Unit | Typical |
| Tensile Strength | N/mm2 | 580 |
| Yield (0.2% proof) | N/mm2 | 440 |
| Elongation | % | 20 |
| Reduction in Area | % | 55 |
| Avg Impact @ -20°C | J | 94 |
| Avg Impact @ -40°C | J | 83 |
| Avg Impact @ -60°C | J | 40 |
| Section size = 360mm (t=1/2) | ||
| Property | Unit | Typical |
| Tensile Strength | N/mm2 | 535 |
| Yield (0.2% proof) | N/mm2 | 350 |
| Elongation | % | 21 |
| Reduction in Area | % | 45 |
| Avg Impact @ -20°C | J | 91 |
| Avg Impact @ -40°C | J | 81 |
| Avg Impact @ -60°C | J | 21 |
Fabrication Welding:
Goodwin alloy G410+ has enhanced weldability characteristics due to controlled CE and PCM values.
Filler Materials:
Weld Repair is carried out using fillers with matching strength and low temperature impact strength:
1% Ni fillers (AWS designation E8018-C3) can be used and give all filler metal proof stress values of typically 470-550N/mm2, and impact strength of 65Joules at -60°C ” as welded “.
Ni content is limited to 1% to meet the requirements of NACE MR0175. It is possible using this filler to carryout minor repairs without PWHT when supported with a conforming weld qualification and procedure.
Alternatively, Mn/Mo filler can be used (AWS designation E9018-D1). The chemistry of this filler is a low carbon steel alloyed with Mn and Mo which enhances hardenability. However, these fillers require PWHT and should not be used in the “as welded” condition giving typical all filler metal proof stress values of 550–600N/mm2 and impacts of 30 to 55 Joules at -50’C. (weld metal hardness hardness typically 210HV)
When yield strength of >410MPa is not required, standard carbon steel fillers can be used for weld repair such as E7018 with typical yield strength after PWHT of 350 to 400MPa.
Post Weld Heat Treatment:
Casting repairs require post weld heat treatment (PWHT) typically 585°C to 630°C. However, PWHT shall always be at least 15’C less than the final tempering temperature.
Machinability
Grade G410+ has good machinability and compares well to conventional carbon steel.
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