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"Gateway
S7 MQ " |
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| Cold
Work |
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| Tool
Steel |
Gateway
S7 MQ |
is a shock resistant alloy tool
steel which provides a unique |
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combination
of machinability, exceptional toughness, ease of heat treatment and
minimum |
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distortion. Special melting and refining practices are
utilized to produce a uniform product with |
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high
cleanliness and minimum segregation.
The material is tested to rigorous tool steel |
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standards to ensure uniformity of
structure and freedom from defects.
Meets ASTM A-681. |
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| Typical
Chemistry |
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Carbon |
.48/.55 |
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Manganese |
.60/.80 |
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Phosphorus |
.010 max |
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Sulfur |
.002 max |
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Silicon |
.20/1.00 |
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Chromium |
3.10/3.50 |
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Vanadium |
.20/.30 |
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Molybdenum |
1.30/1.55 max |
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Oxygen |
20 ppm max. |
Hydrogen |
2 ppm max. |
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| Applications |
Gateway
S7 MQ is suitable for use in applications requiring high impact strength such
as |
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| shears, punches, blanking dies and
chisels. The grade is also used for
high-hardness plastic |
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molds and zinc die casting dies. |
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| Annealing |
Heat slowly and uniformly to
1500/1550 F and hold two hours. Cool
slowly (50 F per hour max) |
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to 1100 F, hold six hours and air
cool. Hardness 210 BHN maximum. |
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| Heat
Treating |
Gateway
S7 MQ is subject to decarburization during heat treatment, so a protective |
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| atmosphere furnace or vacuum furnace
should be used. |
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After preheating to 1200/1250 F,soak
material for one half hour per inch of thickness. |
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When material reaches this
temperature, heat to 1725 F, then soak material for one half hour |
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per inch of thickness when material
is up to this temperature. Air cool
or oil quench to hand |
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warm
(approximately 150 F), and temper immediately. Note sections over two inches thick |
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should be interrupt oil quenched to
attain full hardness. |
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| Tempering |
Double temper one hour per inch of
section thickness to desired hardness at a heating rate of |
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the two tempers. Representative |
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hardness levels after tempering are
tabulated below. |
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Oil Quenched from 1725 F - Tempered
4 Hours |
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(Section Size - 4" x 4") |
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Tempering |
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Tempering |
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Temperature (F) |
Hardness (HRC) |
Temperature (F) |
Hardness (HRC) |
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400 |
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56/58 |
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900 |
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51/53 |
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500 |
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54/56 |
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1000 |
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49/52 |
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600 |
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53/55 |
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1100 |
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46/48 |
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700 |
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52/54 |
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1200 |
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39/41 |
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800 |
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52/54 |
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Note: |
Variations in section size, heating
rate, soak time, quench rate and tempering will |
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cause
deviations from the above values.
Gateway Metals should be consulted for specific |
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applications. The tempering range from 600/800 F should
be avoided due to drop in impact |
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strength. Recommended working hardness ranges are 56/58 or 50/52 HRC. |
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| EDM |
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Electro-discharge machining is
widely used in the production of plastic molds and other tooling. |
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However, this operation produces
recast, rehardened, and retempered layers on the die surface. |
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It
is recommended that Gateway S7 MQ be stress relieved at 50 F below the final
tool |
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tempering
temperature after electro-discharge machining to temper the rehardened layer |
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produced by EDM. |
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