Structural steel with increased cutting machinability A40G

cutting

Initial data			Machinability Ku
State	HB, MPa	sB, MPa	hard alloy	high speed steel
hot rolled	≤207	590	1,3	1,0

physical characteristics

Temperature	E, GPa	G, GPa	r, kg/m3	l, W/(m °С)	R, NOM m	C, J/(kg °C)	a, 10-6 1/°С
0	212	82	7850	—	—	—	—
20	213	—	7850	515	160	483	—
100	206	80	—	51	221	—	119
200	201	78	—	48	296	—	128
300	192	75	—	46	387	—	135
400	176	68	—	42	493	—	141
500	163	63	—	38	619	—	146
600	151	58	—	34	766	—	149
700	131	50	—	30	932	—	152
800	118	45	—	25	1110	—	125
900	—	—	—	26	1150	—	135
1000	—	—	—	269	1180	—	135
1100	—	—	—	28	1207	—	152
1200	—	—	—	295	1230	—	145

Material A40G – mechanical properties

Assortment	GOST	Dimensions – thickness, diameter	Heat treatment mode	t	KCU	y	d5	sT	sв
		mm		0C	kJ/m2	%	%	MPa	MPa
Rolled hot rolled products.	1414–75	20	14	590
Caldibrovan	Annealing	17	590

Description

Steel 40 is used : for the production of rolled sheets 4−14 mm of category 1−2, intended for cold stamping; crankshafts, connecting rods, ring gears, flywheels, gears, bolts, axles and other parts after improvement; shafts and extensions of hydraulic generator shafts; medium-sized parts that require high surface hardness and increased wear resistance with low deformation (long shafts, rollers, gears) after surface hardening with high-frequency heating; parts of pipeline fittings after hardening and tempering; hot-rolled strip profile with slope for agricultural machines; forged blanks of shafts of compressor machines and gas turbines (made of steel 40A); wire used for making spokes for motorcycles and bicycles.

Note

Degree of deoxidation - sp.

Brand A40G - exact and closest foreign analogues

England	Bulgaria	Hungary	Germany	European Union	Spain	Italy
B.S.	BDS	MSZ	DIN, WNR	EN	UNE	UNI
216M36
226M44
44SMn28

44SMn28

A45

ANS2 44SMn28

45S20

46S20

1.0762

44SMn28

45MnS6 CF44SMn28

China	Poland	Romania	USA	France	Czech
G.B.	PN	STAS	—	AFNOR	CSN
Y40Mn

A35G2

A45

AUT40Mn 1141

1144

C1144

G11410

G11440

G11444

G11460

45MF6 11140

What is steel alloy made of?

In addition to the iron and carbon we already know, steel can contain quite a few important components from the periodic table, which to one degree or another affect its properties, directly affecting the characteristics of knife steel. Those elements that are introduced into the alloy to improve its certain properties are called alloying, and steel is called alloyed. Let's start with the required component, and then according to the degree of prevalence in steel.

1. Carbon. Thanks to its presence, steel can be subjected to a hardening process. The alloy contains no more than 2.14%. If there is more of it, then this alloy is called cast iron, if less, then tin. Its task is to provide the alloy with the required strength and hardness, reducing viscosity and flexibility to the required levels. If it contains more than 0.6%, then the alloy is said to be high-carbon. Mid-priced knives, kitchen options often contain carbon from 0.4% to 0.6%.
2. Chromium. Responsible for resisting aggressive air-liquid environments. In other words, it provides knife steel with corrosion resistance. Its content in the alloy must be at least 11.5%. A high chromium content affects hardness. If it is 14% or higher in the alloy, then this steel is classified as “stainless”.
3. Molybdenum. Prevents the appearance of brittleness and fragility of the knife, allows steel for making knives to be resistant to high temperatures. Affects the uniformity of steel composition, increasing the properties of Chromium and improving all properties of the alloy. If its content is more than 1% in steel, then the alloy can be subjected to “air hardening”.
4. Vanadium. Increases wear resistance and strengthens the strength of steel. Its increased hardness is used to create fine-grained alloys, making it possible to obtain a blade with a blade of a high degree of sharpness. However, sharpening such a knife will not be easy.
5. Tungsten. Increases wear resistance and increases the hardness of steel. This chemical element has a melting point higher than other metals. If the alloy contains chromium or molybdenum, then in tandem with any of them, tungsten improves the cutting ability of the knife.
6. Cobalt. It is added in small quantities to alloys, increasing their hardness and cutting properties. Contained in steel in an amount of approximately 1.6%.
7. Nitrogen. Often acts as a substitute for nickel and carbon. If there is not enough carbon in the alloy, adding even 0.1% nitrogen allows the blade to be hardened. It enhances anti-corrosion properties and increases wear resistance.
8. Nickel. Significantly increases the degree of strength, hardness, toughness and anti-corrosion.
9. Silicon. Affects the hardness of the alloy, increases the anti-corrosion properties and degree of strength of the knife, removing oxygen from the metal. It is introduced into steel at the forging and rolling stage.
10. Sulfur. Its content has a good effect on the ability of the knife to be processed. However, it reduces the knife's strength and corrosion resistance.
11. Manganese. Gives steel a grain structure, increasing strength, hardness and wear. Introduced into steel during rolling and forging.
12. Niobium. Titanium. Rare components. Increases corrosion resistance, enhances wear resistance and strength of steel.
13. Phosphorus. It’s better not to be proud of the steel for knives where it exists. Very harmful to knife metals. Increases fragility and brittleness, reduces the mechanical qualities of the alloy. It shouldn't exist at all.

Now, knowing the content of necessary and harmful components, you can easily understand the composition of the alloy. But these are not all “metal” secrets. Now let's get to the fun part - types or brands of steel for knives.

Legend

Mechanical properties

HRСе	HB	KCU	y	d5	sT	sв
MPa	kJ/m2	%	%	MPa	MPa
Rockwell hardness	Brinell hardness	Impact strength	Relative narrowing	Elongation at break	Yield strength	Short-term strength limit

Ku	s0.2	t-1	s-1
Relative machinability factor	Proof of yield strength with 0.2% tolerance when loaded to plastic strain value	Torsional endurance limit (symmetrical cycle)	Endurance limit under compression-tension (symmetrical cycle)

N	number of deformation/stress cycles sustained by an object under load before fatigue failure/crack appears

Steel 40 structural carbon quality

Substitutes

steel, 40G.

Foreign analogues

Germany DIN(EN)	C40 (1.1186)
USA (AISI, ASTM)	104
France (AFNOR)	XC42H1
UK BS	080M40
Japan JIS	S40C, S43C
Czech Republic (CSN)	12041
Poland (PN/H)	40

Decoding steel 40X

The number 40 means that the average carbon content in steel is 0.4%.

Type of delivery

• Long products, including shaped steel: GOST 1050-88, GOST 2590-88, GOST 2591-88, GOST 2879-88, GOST 8509-93, GOST 8510-86, GOST 8239-89, GOST 8240-89, GOST 10702 -78.
• Calibrated rod GOST 10702-78, GOST 7417-75, GOST 8559-75, GOST 8560-78.
• Polished rod and silver steel GOST 10702-78, GOST 14955-77.
• Thick sheet GOST 1577-93, GOST 19903-74, GOST 4041-71.
• Thin sheet GOST 16523-70. Tape GOST 10234-77, GOST 2284-79.
• Strip GOST 103-76, GOST 82-70, GOST 1577-93.
• Wire 17305-91, GOST 5663-79.
• Forgings and forged blanks GOST 8479-70, GOST 1133-71.

Characteristics and description

Steel 40 refers to structural carbon unalloyed special quality steels. Grade 40 steel is recommended for fasteners.

Chemical composition, % (GOST 1050-88)

WITH	Si	Mn	Cr	S	P	Cu	Ni	As
			no more
0,37-0,45	0,17-0,37	0,50-0,80	0,25	0,04	0,035	0,25	0,25	0,08

Chemical composition, % (GOST 1050-2013)

steel grade	Mass fraction of elements, %
	C	Si	Mn	P	S	Cr	Ni	Cu
				no more
40	0,37-0,45	0,17-0,37	0,50-0,80	0,030	0,035	0,25	0,30	0,30

Application

After surface hardening with high-frequency heating, grade 40 steel is used for the manufacture of medium-sized parts that require high surface hardness and increased wear resistance with low deformation, for example:

• long shafts,
• running rollers,
• gear wheels.

After improvement, steel 40 is used to manufacture the following parts:

• crankshafts,
• connecting rods,
• ring gears,
• flywheels,
• gear wheels,
• bolts,
• axes.

In the oil, petrochemical and gas industries, grade 40 steel is used for the manufacture of:

• sucker rod couplings,
• centrifugal pump shafts,
• compressors,
• rotors,
• mud pump rods,
• barrels and swivel subs,
• subs for working and drill pipes,
• core bit bodies,
• fingers of crossheads of mud pumps,
• preventer rollers,
• bevel gears,
• clamps and keys of drilling rigs,
• sprocket wheels of drilling drawworks,
• pins,
• thrust screws,
• rolling pin pumps,
• trunnions, etc.

The use of steel 40 for the manufacture of spindles and rods (GOST 33260-2015)

steel grade	ND for supply	Working environment temperature, °C	Additional instructions for use
40 GOST 1050	Long products GOST 1050	-40 to 425	It is used after heat treatment (hardening and high tempering) at temperatures below minus 31°C to minus 40°C

Use of steel 40 for the manufacture of fasteners (GOST 32569-2013)

steel grade	Technical requirements	Acceptable operating parameters		Purpose
		Wall temperature, °C	Medium pressure, MPa (kgf/cm2), no more
Steel 40 GOST 1050, GOST 10702	STP 26.260.2043	-40 to 425	10 (100)	Studs, bolts
			16 (160)	Nuts
		-40 to 450	16 (160)	Washers

Limits of application, types of mandatory testing and control of steel 40 for flanges for pressures above 10 MPa (100 kgf/cm2) (GOST 32569-2013)

Steel grade, standard or specification		40 GOST 1050
Technical requirements		GOST 9399
the name of detail		Flanges
Limit parameters	Wall temperature, °C, no more	-40 to +200
	Nominal pressure, MPa (kgf/cm2) no more	32 (320)
Mandatory tests	σ0.2	+
	σв	+
	σ	+
	f	+
	KCU	+
	HB	+
Control	Flaw detection	+
	Non-metallic inclusions	—

Resistance of steel 40 against crevice erosion

Durability group	Point	Erosion resistance against steel 12X18H10T
Unstable	6	0,005-0,05

NOTE The coefficient of erosion resistance of a material is the ratio of the rate of erosive wear of the material to the rate of erosive wear of steel 12Х18Н10Т (taken as 1).

Temperature of critical points, °C

Ac1	Ac3	Ar3	Ar1	Mn
730	790	780	690	340

Heat treatment

Parts made of steel grade 40 are subjected to normalization at a temperature of 860-880 ° C or quenching in water from a temperature of 840-860 ° C followed by tempering; The tempering temperature is set depending on the required mechanical properties. For example, parts of drilling rigs (gears, retainer, keys), preventer (main support plate, rollers) are tempered at a temperature of 550°C, and sprockets of a drill drawworks are tempered at a temperature of 500°C.

Hardness HB for metal products made from steel 40 (GOST 1050-2013)

steel grade	Hardness HB, no more, for metal products
	hot rolled and forged		calibrated and with special surface finishing
	without heat treatment	after annealing or high tempering	hard-worked	after annealing or high tempering
40	217	187	241	197

Mechanical properties of metal products (GOST 1050-2013)

steel grade	no less
	Yield strength σt, N/mm2	Tensile strength σв, N/mm2	Relative elongation δ5, %	Relative narrowing Ψ, %
40	335	570	19	45

Mechanical properties of rolled products

GOST	Delivery status	Section, mm	σ0.2, MPa	δ5(δ4), %	Ψ, %	KCU, J/cm2	Hardness HB, no more
			no less
GOST 1050-88	Hot-rolled steel, forged calibrated steel and silver steel of the 2nd category after normalization	25	570	19	45	59	—
	Calibrated steel, category 5:
	after cold hardening	—	610	6	35	—	—
	after annealing or high tempering	—	510	14	40	—	—
GOST 10702-78	Steel calibrated and calibrated with special finishing after tempering and annealing	—	Up to 590	—	40	—	197
GOST 4041-71 (transverse samples)	Heat-treated sheet of categories 1 and 2	4-14	510-650	21	—	—	167
GOST 1577-93	Normalized or hot rolled sheet	80	560	20	—	—	—
	Annealed or high tempered sheet	80	520	21	—	—	—
	Normalized or hot rolled strip	6-25	570	19	45	—	—
GOST 16523-89 (transverse samples)	Hot rolled sheet	Up to 2	510-660	(16)	—	—	—
		2-3,9		(17)	—	—	—
	Cold rolled sheet	Up to 2	510-600	(17)	—	—	—
		2-3,9		(18)	—	—	—
GOST 2284-79	Cold rolled annealed strip	0,1-4	450-700	(14)	—	—	—
	Cold-worked tape, strength class H2	0,1-4	850-1050	—	—	—	—
GOST 10234-77	Annealed flattened strip	0,1-4	Up to 700	10	—	—	—

Mechanical properties of forgings (GOST 8479-70)

Heat treatment	Section, mm	KP	σ0.2, MPa	σв, MPa	δ5, %	Ψ, %	KCU, J/cm2	Hardness NV, no more
			no less
Normalization	300-500	215	215	430	18	40	44	123-167
	500-800				16	35	39
	100-300	245	245	470	19	42	39	143-179
	300-500				17	35	34
	Up to 100	275	275	530	20	40	44	156-197
	100-300				17	38	34
Quenching+tempering	300-500	275	275	530	15	32	29	156-197
	500-800				13	30	29
	100-300	315	315	570	14	35	34	167-207
	Up to 100	345	345	590	18	45	59	174-217

Mechanical properties after quenching at 850 °C in oil

ttp, °С	σ0.2, MPa	σв, MPa	δ5, %	Ψ, %	KCU, J/cm2	Hardness NV, no more
200	750	930	7	45	29	267
300	710	860	8	51	69	247
400	640	790	10	57	88	225
500	550	730	12	62	127	208
600	450	660	16	66	167	188
700	380	620	17	71	206	170

Mechanical properties at elevated temperatures [81]

tsp, °С	σ0.2, MPa	σв, MPa	δ5, %	Ψ, %
700	99	140	48	85
800	70	110	53	97
900	54	71	55	100
1000	28	58	69	100
1100	24	37	60	100
1200	16	26	87	100
1300	12	18	56	100

NOTE. Sample with a diameter of 6 mm and a length of 80 mm, rolled. Deformation speed 16 mm/min; strain rate 0.009 1/s.

Impact strength KCU [28]

Heat treatment	KCU, J/cm2, at temperature, °C
	+20	-40	-80
Quenching at 850 °C in water; tempering at 400 °C	78	55	51

Endurance Limit [140]

Heat treatment	σ-1, MPa
Annealing at 850 °C, σ0.2 = 275 MPa, σв = 520 MPa	231
Quenching at 845 °C in water; tempering at 550 °C, σ0.2 = 600 MPa, σв = 710 MPa, НВ 209	393
Quenching from 845 °C into oil; tempering at 430 °C, σ0.2 = 415 MPa, σв = 630 MPa	230

NOTE. σ4001/100000 = 100 MPa; σ4501/100000 = 50 MPa; σ5001/100000 = 30 MPa; σ4001/10000 = 260 MPa; σ5001/10000 = 70 MPa; σ4001/100000 = 190 MPa; σ5001/100000 = 44 MPa.

Technological properties [81]

Forging temperature, °C: start 1250, end 800. Cooling of workpieces with a cross-section of up to 400 mm in air.

Weldability - limited weldability. Welding methods: RDS, ADS under submerged arc and gas shield, ESW. Preheating and subsequent heat treatment are recommended. CTS without restrictions.

Cutting ability - Kv tv.spl = 1.2 and Kv b.st = 1.05 in the hot-rolled state at HB 170 and av = 520 MPa.

Flock sensitivity - not sensitive.

Tendency to temper brittleness - not prone.

Hardenability, mm (GOST 1050-88) [51]

The hardenability band of steel 40 after normalization at 850 °C and quenching from 850 °C is shown in the figure below.

Critical diameter d after quenching from 850 °C

Amount of martensite, %	d, mm, after hardening
	in water	In oil
50	15-25	8-15
90	10-15	5-9,5

Density ρ kg/cm3 at test temperature, °C

Steel	20	100	200	300	400	500	600	700	800	900
40	7850	—	—	—	—	—	—	—	—	—

Linear expansion coefficient α*106, K-1

steel grade	α*106, K-1 at test temperature, °C
	20-100	20-200	20-300	20-400	20-500	20-600	20-700	20-800	20-900	20-1000
40	11,9	12,8	13,5	14,1	14,6	14,9	15,2	12,5	13,5	14,5

Thermal conductivity coefficient λ W/(m*K)

Steel grade	λ W/(m*K), at test temperature, °C
	20	100	200	300	400	500	600	700	800	900
40	—	51	48	46	42	38	34	30	25	26

Specific heat capacity c, J/(kg*K)

steel grade	s, J/(kg*K), at test temperature, °C
	20-100	20-200	20-300	20-400	20-500	20-600	20-700	20-800	20-900	20-1000
40	486	497	512	529	550	574	628	674	657	653

Modulus of normal elasticity E, GPa

Steel grade	At test temperature, °C
	20	100	200	300	400	500	600	700	800	900
40	212	206	201	192	176	163	151	131	118	—

Modulus of elasticity in torsional shear G, GPa

steel grade	At test temperature, °C
	20	100	200	300	400	500	600	700	800	900
40	82	80	78	75	68	63	58	50	45	—

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