A564-B24 Alloy Steel Bolting for Special

A564-B24 Alloy Steel Bolting for Special
STEELMAX Steel Story

A564 Standard Specification for
Alloy Steel Bolting for Special Applications 규정입니다.

Ni+Cr+Mo 합금강으로
얼핏 보면 JIS/KS의 SNCM439 같아 보이지만

다른 강재임에
유의해야 합니다.

※ Alloy steel
A Carbon steel to which is added a definite amount of one or more
elements other than carbon, in order to impart special properties
to the steel so that it can be used for specific purposes.

강의 성질을 향상 시키기 위해, 또는 소정의 성질을 구비 시키기 위해
합금 원소를 1종 또는 2종 이상을 합금 시킨 강.

※ Steel (강 : 鋼)
Iron, malleable in at least one range of temperature below its melting
point without special heat treatment, substantially free from slag, and
containing carbon more than about 0.05% and less than about 2.00%.
Other alloying elements may be present in significant quantities, but
all steels contain at least small amounts of manganese and silicon,
and usually as undesirable constituents, also sulfur and phosphorus.

Steel can be classified on the base of :
– Composition (carbon steel, low alloy steel, high alloy steel, etc.)
– Finishing method (hot rolled steel, cold rolled steel, PM steel, cast steel, etc.)
– Production form (plate, sheet, strip, bar, h-beam, rail, etc.)
– Type of application (construction steel, shipbuilding steel, tool steel, etc.)

Identification Symbol/Grade		ASTM A540 B24 Cl.3 / 4340 Mod
Chemical Composition (%)	Carbon (C)	0.37~0.44
	Manganese (Mn)	0.70~0.90
	Phosphorus (P)	0.025 max
	Sulfur (S)	0.025 max
	Silicon (Si)	0.15~0.35
	Chromium (Cr)	0.70~0.95
	Nickel 9Ni)	1.65~2.00
	Molybdenum (Mo)	0.30~0.40
Yield strength	Class 3	130 ksi (895 MPa) min
Tensile strength	Class 3	145 ksi (1000 MPa) min
Elongation (%)	Class 3	12
Hardness (BHN)	t＜75	293~363
Hardness (BHN)	t≤75＜200	302~388