Jun 20 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Forging
Annealing
Stress Relieving
Hardening
Quenching
Tempering
Applications
Introduction
Tool steels are high-quality steels that have good hardness, abrasion resistance and good machinability. They are generally used in a heat-treated state. Tool steels are used for special applications such as injection molding, plastic molding, die casting, extrusion and forging.
AISI H43 tool steels are high vanadium-moly chrome premium hot working steel having excellent abrasion and heat resistance. The following section will provide an overview of the grade H43 tool steels.
Chemical Composition
The chemical composition of H43 tool steels is outlined in the following table.
|
Element |
Content (%) |
|
Molybdenum, Mo |
7.75-8.5 |
|
Chromium, Cr |
3.75-4.5 |
|
Vanadium, V |
1.8-2.2 |
|
Carbon, C |
0.5-0.65 |
|
Silicon, Si |
0.2-0.45 |
|
Manganese, Mn |
0.15-0.4 |
|
Phosphorus, P |
0.03 |
|
Sulfur, S |
0.03 |
Physical Properties
The following table shows the physical properties of H43 tool steels.
|
Properties |
Metric |
Imperial |
|
Density |
7.7 g/cm3 |
0.278 lb/in3 |
|
Melting point |
1450-1510°C |
2642-2750°F |
Mechanical Properties
The mechanical properties of H43 tool steels are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
650-880 MPa |
167.95 ksi |
|
Elongation |
8-25% |
15% |
|
Modulus of elasticity |
190-210 GPa |
27557- 30457 ksi |
|
Poisson’s ratio |
0.27-0.3 |
0.27-0.3 |
Thermal Properties
The thermal properties of H43 tool steels are given in the following table
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient |
10 µm/m°C |
5.5 µin/in°F |
|
Thermal conductivity |
25 W/mK |
173 BTU.in/hrft².°F |
Fabrication and Heat Treatment
Forging
H43 tool steels are forged slowly and uniformly at 3092 - 3272°C (1700-1800°F). The material is cooled slowly in lime, mica or dry ashes when dried.
Annealing
H43 tools steels are annealed slowly at 2732 - 2822°C (1500-1550°F) followed by slow cooling to about 1832°C (1000°F).
Stress Relieving
The annealed materials are then stress relieved by heating at 2102 - 2282°C (1150-1250°F), allowed to equalize and cooled in still air.
Hardening
The materials are transferred to the hardening furnace operating at 3902 - 3992°C (2150-2200°F) based on the degree of hardening required for specific applications.
Quenching
H43 tool steels are quenched in air, oil or molten salt bath at 1832 - 2012°C (1000-1100°F).
Tempering
Tempering is usually carried out at 1832 - 2012°C (1000-1100°F), but the temperature can be varied according to the desired hardness.
Applications
H43 tool steels are mainly used for severe hot work applications such as forming rolls, dies and punches where abrasion and wash resistance is required.