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U9A steel

U9A steel

Steel U9A: Handbook of steels and alloys. Below is systematized information on the purpose, chemical composition, types of supply, substitutes, critical point temperatures, physical, mechanical, technological and foundry properties for the grade — Steel U9A.

General information on steel U9A

Substitute for the grade
Of steel grade: У7А, У7, У8А, У8.
Type of delivery
Sections, including shaped: GOST 1435−74, GOST 2590−71, GOST 2591−71, GOST 2879−69. Calibrated rod GOST 1435−74, GOST 7417−75, GOST 8559−75, GOST 8560−78. Grinded rod and silversilver GOST 1435−74, GOST 14955−77. Tape GOST 2283−79, GOST 10234−77. Tape GOST 103−76, GOST 4405−75. Forgings and forged blanks GOST 1435−74, GOST 4405−75, GOST 1133−71.
Application
The tools working in the conditions which do not cause heating of the edge: a tool for woodworking, welding and assembly tools, the calibers of the simple form and the lowered classes of accuracy.

Chemical composition of U9A steel

Chemical element %
Silicon (Si) 0.17−0.33
Manganese (Mn) 0.17−0.28
Copper (Cu), not more 0.20
Nickel (Ni), not more than 0.20
Sulfur (S), not more than 0.018
Carbon (C) 0.86−0.93
Phosphorus (P), not more than 0.025
Chromium (Cr), not more than 0.20

Mechanical properties of U9A steel

Mechanical properties

Heat treatment, delivery condition σB, MPa δ5, %
Rolled section 0,1−4,0 mm.
Cold rolled annealed strip 750 10
Cold-rolled annealed strip 750−1200  
Cold-rolled flat steel strip, strength class H1 750−900  
Cold-rolled flat steel strip, strength class H2 900−1050  
Cold-rolled flat steel strip, strength class H3 1050−1200  
Strip annealed of the highest quality category. 700 15

Technological properties of U9A steel

Forging temperature
Beginning 1125, end 750.
Weldability
Not applicable for welded structures.
Tendency to tempering ability
is not prone to
Flockability
is not sensitive

U9A steel critical point temperature

Critical point °С
Ac1 740
Ac3 760
Ar1 700
Mn 190

U9A steel hardness

Delivery condition, heat treatment regime HRCe surface HB
750−770 C annealing.   192
Tempering 760−780 C, water. 63  
Springs. Isothermal hardening 770 C, cooling in an alkaline bath at 340−360 C. Tempering for 10−15 minutes. Tempering at 170 C. 45−50  
Tempering at 800 °C with water. Tempering at 200 C. 61  
Hardening 800 C, water. Tempering at 300 °C. 52  

Hardenability of U9A steel

Hardening at 760 °C.

Distance from end face, mm / HRCe
1.5 3 4.5 6 9 12 15 18 30 42
63 61 58 53,5 48 46 45,5 45,5 44,5 42,5
Crit. dia. in water, mm Crit. dia. in oil, mm
15−20 4−6

Physical properties of U9A steel

Test temperature, °С 20 100 200 300 400 500 600 700 800 900
Modulus of normal elasticity, E, GPa 207                  
Torsional shear modulus of elasticity G, GPa 79                  
Steel density, pn, kg/m3 7745 7726 7717 7690 7686 7655 7622 7586 7568 7523
Thermal conductivity coefficient W/(m — °C)   49 48 46 43 40 37 33    
Electrical resistivity (p, nominal value — m)   253 329 418 525 646 789 943 1155 1198
Test temperature,°C 20−100 20−200 20−300 20−400 20−500 20−600 20−700 20−800 20−900 20−1000
Coefficient of linear expansion (a, 10−6 1/°C) 11.3 12.1 12.9 13.6 14.2 14.7 15.2 14.0