AISI/SAE H21 Tool Steel /1.2581/SKD5/3Cr2W8V

• Customization: Available
• Type: Round
• Standard: AISI, ASTM, DIN, JIS, GB, BS
• Model NO.: round bar
• Composition: Stainless Steel Scrap
• Technique: Hot Rolled
• Shape: Bar
• Surface Treatment: Polished
• Special Use: High-strength Steel Plate, Wear Resistant Steel, Silicon Steel, Cold Heading Steel, Free Cutting Steel, Mold Steel
• Application: Die Steel Bar
• Transport Package: Wooden
• Specification: 6-400mm
• Trademark: Smooth
• Origin: China
• HS Code: 7214100000
• Production Capacity: 5000 Ton/Year

Product Description

AISI/SAE H21/1.2581/SKD5/3Cr2W8V
Brief Description
H21 Tool Steel is a kind of hot die steel with air cooling hardening, and is one of the most widely used steel in all hot die steel. Compared with H11 steel, H21 has higher thermal strength and hardness. It has good toughness,thermal fatigue properties and certain wear resistance under the condition of medium temperature. Air quenching in low austenitic temperature,heat treatment deformation is small. The tendency to produce oxidized iron sheet during air quenching is small, and H21 can resist erosion of molten aluminum.
1.Size Range for H21 Tool Steel
H21 Steel Round Bar: diameter 80mm~330mm
H21 Steel Plate: thickness 25mm~400mm x width 200mm~800mm
Delivery Condition:
Tured Round Bar,Milling Plate,Black,requiremts for customers.
Spheroidizing Annealing,ESR material.
2.H21 Tool Steel Equivalent Grades

Country	USA	German		Japan	China
Standard	ASTM A681	W-nr.	DIN	JISG4404	GB/T1299-2000
Grades	H21	1.2581	X30WCrV93	SKD5	3Cr2W8V

3.H21Tool Steel Chemical Composition

Grades	C%	Si%	Mn%	P%	S%	Cr%	W%	V%
H21	0.26~0.36	0.15~0.50	0.15~0.40	≤0.030	≤0.030	3.00~3.75	8.50~10.0	0.30~0.60
1.2581	0.25~0.35	0.15~0.30	0.20~0.40	≤0.035	≤0.035	2.50~2.80	8.00~9.00	0.30~0.40
SKD5	0.25~0.35	0.10~0.40	0.15~0.45	≤0.030	≤0.020	2.50~3.20	8.50~9.50	0.30~0.50

4.H21 Tool Steel Physical Properties
H21 Critical temperature

Critical point	Ac1	Ac3	Ar1
Temp.(approx.)	1508~1526°F(820~830°C)	2012°F(1100°C)	1454°F(790°C)

Coefficient of linear thermal expansion

Temp./ °C	100	200	300	400	500	600	700	800
Coefficient/°C^-1(x10^-6)	14.3	14.7	15.6	16.3	16.1	15.2	15.0	28.0

Specific heat at constant pressure

Temp. /°C	100	200	500	800	900
Cp/J •(kg•K)^-1	468.2	525.5	685.5	1262.4	660.4

Thermal conductivity of H21

Temp. /°C	100	200	700	900
λ/W•(m•K)^-1	20.1	22.2	24.3	23.0

Resistivity of H21

Temp./ °C	20	200	500	700	900
ρ/Ω•m	0.5 x10^-6	0.6 x10^-6	0.8 x10^-6	1.0 x10^-6	1.19 x10^-6

5.Forging of H21 Tool Steel
H21 hot working technology

Items	Heating temperature	Starting forging temperature	Final forging temperature	Cooling
Ingot	2102~2192°F (1150~1200°C)	2012~2102°F (1100~1150°C)	1562~1652°F (850~900°C)	Cooling in the air, then in hole or sand
Billet	2066~21202°F (1130~1160°C)	1976~2048°F (1080~1120°C)	1562~1652°F (850~900°C)	Cooling in the air, then in hole or sand

After forging,it shall be cooled in the air below the temperature of A_c1(abou 700°C) and then slowly cooled(sand cooling or furnace cooling).If conditions permit,hot charging annealing can be carried out directly.
6.Heat treatment of H21 Tool Steel
  Annealing
Heat slowly to 1600~1650 °F(870~900°C), hold until the entire mass is heated through, and cool slowly in the furnace (40°F per hour) to about 1000°F(538°C), after which the cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.
Stress Relieving
  When desirable to relieve the stress of machining, heat slowly to 1050~1250°F(565~677°C), allow to equalize, cool in still air.
  Preheat for Hardening
  Warm slightly before charging into the furnace, which should be operating at 1500~1550°F(815~843°C).
  Hardening
  After thorough preheating, transfer to hardening furnace operating at 2050~2200°F(1121~1204°C), depending upon the degree of hardening required for the application, and the size of the tool, a salt bath or controlled atmosphere furnace is desirable. If these are not available, pack hardening in spent pitch coke is suggested. Long soaking times at the hardening temperature are not recommended because of the danger of grain growth.
  Quenching
Cool in air, oil or a molten salt bath operating at 1000-1100°F(537~593°C). In the case of oil quenching, it is usually good practice to interrupt the quench by removing the tool after it has reached about 1000°F(537°C), and allow the cooling to continue in still air. The tool should be allowed to cool to 150°F(65°C), or to where it can be held in the bare hand, and then tempered immediately.
Tempering
Tempering practice may vary with size and application,but is usually performed in the range of maximum secondary hardness or higher. Double tempering is recommended. The following chart may be used as a guide to the hardness that may be expected after tempering.

Double tempered	Oil quenched from 2150°F(1176°C)
950°F(510°C)	52.0RC
1000°F(537°C)	53.0RC
1050°F(565°C)	52.2RC
1100°F(593°C)	51.5RC
1150°F(621°C)	50.0RC
1200°F(648°C)	45.0RC
1250°F(677°C)	39.0RC

7.Applications of H21 Tool Steel
H21 is particularly useful for hot forging and blanking dies and punches for making nuts, bolts and other similar small components. Dies, cores, inserts, pins, etc for the die casting of copper base alloys are also prime applications for this steel. Other uses include forming dies, shear blades, hot extrusion dies, mandrels, punches, die holders, ejector discs and extrusion liners.