Introduction:
M42 high speed steel is a premium cobalt high speed steel with a chemical composition designed for high hardness and superior hot hardness. These properties make the steel an excellent choice for machining high-strength and pre-hardened steels, high-hardness alloys, and the difficult-to-machine, nonferrous super alloys used in the aerospace, oil, and power generation industries.
M42 high speed steel exhibits excellent wear resistance by virtue of high heat-treated hardness (68 to 70 HRC), and the high cobalt content imparts the hot hardness. As such, the cutting edges on tools made from M42 high speed steel stay sharp and hard in heavy-duty and high-production cutting applications.
Applications:
M42high speed steel can be used in conditions where the demand for hot hardness is important. Commonly used for cutting tools including twist drills, taps, broaches tools, milling cutters, reamers, end mills, bandsaw blades, cold work tools, and thread rolling dies.
PROPERTIES:
M42 high speed steel is highly Cobalt alloyed. The composition of M42 speed steel makes for a good combination of toughness and hardness. By virtue of these well-balanced properties M42 high speed steelhas come into wide use for all cutting tools.
Characteristics:
· All-round applicability
· Good machine-ability
· Good performance
· Good hot hardness
· Good wear resistance
Size available:
· Round Bar: Dia2mm-Dia200mm
· Flat: thickness, width, contracted.
Quality Standard:
ASTM A600 Standard Specification for High Speed Steel.
All Grades Comparison:
AISI |
DIN |
AFNOR |
JIS |
UNS |
| M42 |
DIN 1.3247 |
07-05-04-04-02 |
SKH59 |
T11342 |
Chemical Composition(%)
C |
Si |
Mn |
P |
S |
Cr |
Ni |
Mo |
V |
W |
Co |
Cu |
| 1.05-1.15 |
0.15-0.65 |
0.15-0.40 |
0.030 max |
0.030 max |
3.50-4.25 |
0.3 max |
9.00-10.00 |
0.95-1.35 |
1.15-1.85 |
7.75-8.75 |
0.25 max |
METHODS OF MAKING TOOLS:
M42 high speed steel can be worked in the same way as other high-speed steels by plastic forming, machining, grinding, electrical discharge machining, welding and polishing. In grinding, local heating of the surface, which might alter the temper, must be avoided. Grinding wheel makers can furnish advice on the choice of grinding wheels. Machining is carried out using carbide or high speed steel tools.
Final Grinding
Select the correct grade of wheel in consultation with the grinding wheel manufacturer. Ensure the grinding wheel is in good condition by means of a suitable dressing tool. Wet grinding is a preferable option using a copious supply of coolant. If dry grinding is resorted to then use a very soft wheel.
HEAT TREATMENT:
Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each M42 high speed steel component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities.
Forging:Pre heat the M42 high speed steel slowly and uniformly to 650-760°C and equalise. Then increase more quickly to the forging temperature of 1010-1150°C and equalise prior to forging. Do not allow the forging temperature to drop below 980°C, if this occurs re heating will be necessary. Always cool the high speed steel very slowly after forging.
Annealing:Annealing of M42 high speed steel is recommended after hot working and before rehardening. Heat the M42 high speed steel to 850°C at a rate of no more than 220°C per hour. Always hold at temperature for one hour per 25mm of thickness (with two hours being minimum). Furnace cool slowly. The M42 high speed steel annealed hardness achieved should be 269 Brinell or lower.
Stress Relieving:If tools produced from M42 high speed steel are heavily machined or ground it is recommended to stress relieve after machining and prior to hardening to minimise the possibility of distortion. To stress relieve heat the component to 600-650°C and soak well (approximately two hours) Cool slowly in the furnace. The M42 high speed steel tools can be finish machined before heat treatment.
Hardening:For best results harden in a vacuum or controlled furnace, or in a properly rectified salt bath. Pre heat thoroughly in two steps to 450-500°C, then to 820-870°C, transfer to the high temperature salt bath or furnace. The exact hardening temperature to use for M35 will depend on the type of work being treated, but in general components should be hardened from the range of 1050-1250°C.
Tempering:For best results harden the M42 high speed steel in a vacuum or controlled furnace, or in a properly rectified salt bath. Pre-heat the steel thoroughly to 820-870°C then transfer to the high temperature salt bath or furnace. The exact hardening temperature to use for M42 high speed steel will depend on the type of work being treated, but in general components should be hardened from the range of 1160-1180°C in salt, or 1180-1190°C in atmosphere or vacuum furnaces. After a short hold at the hardening temperature, quench the component without further soaking into salt at 540-595°C or warm oil. If salt quenched allow the component to equalise at the bath temperature and then complete the quench in still air.
Temperature [°C] 500 550 600
Hardness [HRc] 67 69 63
Mill's test certificate:
EN 10204/3.1 with all relevant data reg. chem. composition, mech. properties and results of testing.
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