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 Shock Resistant Tool Steel 

Precision Marshall’s SUPER 7 MQ® is a premium shock resistant tool steel which provides a unique combination of machinability, exceptional toughness, ease of heat treatment and minium distortion. Special melting and refining practices are utilitzed to produce a uniform product with high cleanliness and minimum 

segregation. The material is tested to rigorous tool steel standards to ensure uniformity of structure and freedom from defects. Meets ASTM A-681. 


Carbon.48/.55 .50Chromium3.10/3.503.30
Phosphorus.010 max.005Silicon.20/1.00.50
Sulfur.002 max.0005Vanadium.20/.30.25
Copper.25 maxTungsten.30 max
Nickel.40 max


SUPER 7 MQ® is suitable for use in applications requiring high impact strength such as shears, punches, blanking dies and chisels. SUPER 7 MQ®’’s superior cleanliness and soundness makes it suitable for high-hardness plastic molds and zinc die casting dies


Heat slowly and uniformly to 1500/1550°F and hold two hours. Cool slowly (50°F per hour max.) to 1100°F and air cool to room temperature. Hardness 229 BHN maximum. 

Heat Treating

Precision Marshall’s SUPER 7 MQ® is subject to decarburization during heat treatment, so a protective atmosphere furnace or a vacuum furnace should be used. 

After preheating 1200/1250°F, soak material for one half hour per inch of thickness. When material reaches this temperature, heat to 1725°F, then soak material for one half hour per inch of thickness when material is up to this temperature. Air cool or oil quench to hand warm (approximately 150°F) and temper immediately. Note: Sections over two inches thick should be interrupt oil quenched or full oil quenched to attain full hardness. 


Double temper one hour per inch of section thickness to desired harness, two hours minimum per temper. Representative hardness levels after tempering are tabulated below. 

 Oil quenched from 1750°F • Tempered 4 hours (Section Size — 4” x 4”) 

 Tempering Temperature (°F) Rockwell Hardness (RC) Tempering Temperature (°F) Rockwell Hardness (RC) 
400 56/58 900 51/53 
500 54/56 1000 49/52 
600 53/55 1100 46/48 
700 52/54 1200 39/41 
800 52/54


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 SUPER 7 be stress relieved at 50°F below the final tool tempering temperature, after the EDM process, to temper the rehardened layer produced by EDM. 


SUPER 7 MQ® is provided completely decarb free and stress relieved. 


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


Available in standard thickness increments 1/4” thru 8”.