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 Prehardened Alloy Steel 

Precision Marshall’s MARSHALLOYTM STD is a prehardened, high-quality, 4140/4142 modified, alloy steel intended for all mechanical uses where improved machinability, uniform hardness and excellent flatness are required. Product hardness range is 262-321 Brinell. 

 Typical Analysis 

Phosphorus.035 maxSilicon.25
Sulfur.040 max


MARSHALLOY STD is a high quality prehardened alloy steel intended for use in a variety of mechanical applications where the combination of good machinability and medium hardness is required. Specific applications include short run tools and dies, prototype dies, guide rails, back up plates and support tooling, jigs and fixtures and holder blocks. MARSHALLOY STD can also be used for molds with less critical cleanliness and polishability requirements. 

Stress Relief

Heat slowly and uniformly to 1000°F and soak one hour per inch of section thickness. Air cool or furnace cool to room temperature. 


It is recommended that MARSHALLOY™ STD be annealed prior to rehardening. Heat slowly and uniformly to 1500/1600° for four hours. Cool slowly (50°F per hour max.) to 1200°F and air cool. 

Heat Treating

MARSHALLOY STD 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.After preheating to 1500°F for one half to one hour, heat to 1750/1800°F and soak one half hour when material is up to temperature. Air cool to hand warm (approximately 150°F) and temper immediately. 


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 Size — 4” x 4”) 

 Tempering Temperature (°F) Hardness (RC) 
400 42 
500 41 
600 40 
700 39 
800 37 
900 36 
1000 34 
1100 29 
1200 25 


Electro-discharge machining is used in the production of various tooling. This process produces recast, rehardened and retempered layers on the EDM surface. It is recommended that MARSHALLOY™ STD be stress relieved at 50°F below the final tool tempering temperature, after the EDM process, to temper the rehardened layer produced by EDM. 


MARSHALLOY STD is provided completely decarb free and stress relieved. 


Ground oversize to typical rms 50/75, maximum 125. 


Available in standard thickness increments 1/4” thru 4”.