4140 Alloy - Also called "chrome-moly" steel. Ideal for forging and heat treating, 4140 alloy is tough, ductile, and wear resistant. Max_ attainable Rockwell hardness is C20-C25. Melting point is 2750째 F. Yield strength is 60,000-105,000 psi. 4140 ASTM A193 Grade B7 Alloy - Similar to 4140 alloy, but it's already quenched, tempered, and stress relieved. Rockwell hardness is C35 max_
8630 Alloy This alloy is tough yet ductile. It responds well to heat treating, exhibits superb core characteristics, and has good weldability and machining properties. Max. attainable Rockwell hardness is B85-B97. Melting point is 2800째 F. Yield strength is 55,000-90,000 psi. One of the more common alloys is 1144, a carbon steel in which alloying elements enhance machining.
1144 stress-proof, a product of LaSalle Steel, is an example of an alloy with good machining and hardenability features that possesses high strength and can be through hardened. Chrome alloy steels, such as 4130, 4140, and 4340 are so named because chromium content is high (around 1%), and is the primary alloying element. As one can see, chrome alloy steels begin with "40" prefix and end in two numbers that account for the nominal percentage of carbon. For example, 4140 has 0.40% of carbon and 0.1 % chromium. Nickel alloy steels substitute nickel in place of roughly half of standard chromium contents for chrome alloys. For example, whereas 4140 has 0.0% nickel and 0.1 % chromium, 8630 has 0.60% nickel and 0.50% chromium. These alloys are normally prefixed with "80" numbers. 8630 compare to 4140 as follows: C Mn Si P S Cr Ni Mo Other 8630 0.25-0.35 0.65-0.85 0.70 0.04 0.04 0.40-0.70 0.40-0.70 0.20-0.30 4140 0.38-0.43 0.75-1.00 0.035 0.04 0.15-0.35 0.8-1.10
It is difficult to make mechanical comparisons between chrome alloys and nickel alloys as they are similar but unique to a grade. Generally nickel alloys can be drawn to a more precise finish size and therefore are more common in end use steels such as keystock.
Bright Steels Because of the relevance of these grades to the G.L. Huyett product line, we are giving separate coverage here. Bright steels typically refer to a class of cold finished square and rectangle bars that are drawn to more exacting tolerances; they possess sharp corners, perpendicular and parallel sides, and my be bead blasted to make them "bright." Bright steels are also known as keystock. Keystock squares and rectangles are more difficult to draw than rounds because of the 90째 angled corners. Bars must be straight and true and the width must be in a perpendicular plane with the height. The surface finish of keystock must be free of pits and stresses so that installation is smooth and efficient. Most customers prefer sharp corners for increased keyway contact (and minimal rocking), but edges must be sufficiently deburred for ease of use.
Perpendicular Planes
Straight
Sharp Corners
Bright Finish
90'
on
The definition of keystock has been elusive because no single standard exists. Most technicians refer to
"barstock" or "key barstock" as cold finished material drawn from market-ready grades to marketready tolerances. "Keystock" refers to barstock carefully drawn to ANSI Class 2 fits.
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