The Grade B7M Alloy-Steel and Stainless-Steel Bolting Materials for High Temperature or High Pressure Service and Other Special Purpose Applications

This Grade B7M is heavily utilized in petroleum, Sewage, Water treatment and chemical construction applications. The ASTM standard covers alloy steel and stainless steel bolting materials for high temperature or high-pressure service. This specification includes fasteners intended for use in pressure vessels, valves, flanges, and fittings. Although, this material is often available in national coarse (UNC) thread pitches, if being used in traditional applications, threads are specified 8 threads per inch (tpi) for diameters above one inch.

B7M

Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines

Property class	Chemical composition
	C.	Mn.	Si.	P.	S.	Cr.	Ni.	Mo.	V.	Ti.
B7M	0.37---0.49	0.65---1.10	0.15---0.35	0.035 max.	0.04 max.	0.75---1.20	---	0.15---0.25	---	---

Class	Diameter, [Inch]	Minimum Tempering Temperature, °C	Tensile Strength, min, MPa	Yield Strength, min, 0.2 % offset, MPa	Elongation in 4D, min, %	Reduction of Area, min, %	Hardness, max
B7MA Chromium-molybdenum	4 and under	1150	100	80	18	50	235 HB or 99 HRB
	over 4 to 7	1150	100	75	18	50	235 HB or 99 HRB

Class	Diameter, [mm]	Minimum Tempering Temperature, °C	Tensile Strength, min, MPa	Yield Strength, min, 0.2 % offset, MPa	Elongation in 4D, min, %	Reduction of Area, min, %	Hardness, max
B7MA Chromium-molybdenum	M100 and under	620	690	550	18	50	235 HB or 99 HRB
	over M100 to M180	620	690	515	18	50	235 HB or 99 HRB