Marshalloy MQ®/FM
Prehardened Alloy Steel
MARSHALLOY MQ®/FM, exclusively by Precision Marshall Steel, is a mold quality steel supplied in the prehardened condition. Special melting and refining practices are utilized to produce a uniform product with exceptional cleanliness. These characteristics allow MARSHALLOY MQ®/FM to be polished to an extremely high finish required for plastic molding. The material is tested to rigorous standards to ensure uniformity of structure and exceptionally low inclusion levels.
MARSHALLOY MQ®/FM is supplied prehardened to 280/321 BHN. The balanced composition ensures uniform cross-sectional hardness and is guaranteed to maintain the specified hardness throughout the plate. Maximum variation within any plate is 30 BHN.
MARSHALLOY MQ®/FM provides superior machinability while demonstrating outstanding cleanliness and soundness. It may be successfully substituted for P20 for plastic injection mold applications in addition to its usefulness in a wide range of mechanical applications, including short run tools and dies.
Attributes
EDM
Electro-discharge machining is used in the production of various tooling. This process produces recast, rehardened and retempered layers An the EDM surface. It is recommended that MARSHALLOY MQ®/FM be stress relieved at 50°F below the final tool tempering temperature, after the EDM process, to temper the rehardened layer produced by EDM.Condition
MARSHALLOY MQ®/FM is provided completely decarb free and stress relieved.Finish
Oversize to typical rms 50/75, maximum 125.Sizing
Available in standard thickness increments 1/2″ through 4″. Note: MARSHALLOY MQ®/FM sizes above 4″ may have milled finish.Chemistry
| ELEMENT | RANGE | AIM |
|---|---|---|
| Carbon | .36/.42 | (.40) |
| Manganese | 1.10/1.30 | (1.20) |
| Phosphorus | .010 max | – |
| Sulfur | .010/.022 | (.015) |
| Chromium | 1.00/1.20 | (1.10) |
| Molybdenum | .15/.35 | (.25) |
| Silicon | .35/.45 | (.40) |
| Nickel | .25/.50 | (.35) |
| Copper | .30 max | – |
Additional Information
Stress Relief
Heat slowly and uniformly to 800/900°F and soak one hour per inch of section thickness. Air cool or furnace cool to room temperature.Annealing
It is recommended that MARSHALLOY MQ®/FM be annealed prior to rehardening.Heat slowly and uniformly to 1500/1600°F for four hours. Cool slowly (50°F per hour max.) to 1200°F and air cool.Heat Treating
MARSHALLOY MQ®/FM may be heat treated to higher levels of hardness for higher strength. Preheat to 1250°F and hold for one hour. Heat to 1550/1600°F and soak one half hour when material is up to temperature. Oil quench or air cool to hand warm (approximately 150°F) and temper immediately.Tempering
Temper one hour per inch of section thickness to desired hardness. Representative hardness levels after tempering are tabulated below.
Oil quenched from 1600°F • Tempered 4 hours • Section 4″×4″
| TEMPERING TEMPERATURE (°F) | ROCKWELL HARDNESS (RC) |
|---|---|
| 400 | 42 |
| 500 | 41 |
| 600 | 40 |
| 700 | 39 |
| 800 | 37 |
| 900 | 36 |
| 1000 | 34 |
| 1100 | 29 |
| 1200 | 25 |
