T1 type high speed steel was developed at the beginning of this century. This steel, 18-4l, is the predecessor of modern high speed steel. T1 grade has maintained its position for many years and is still used to some extent. By adding about 5-10% CO and increasing the content of C and V at the same time, the wear resistance is increased. The common denominator of all 18-4 litre steels is their high hardening temperature, i.e. 1260 ° C to 1280 ° C, so it is impossible to use a hardening temperature of 1280 ° C to cause any danger of overheating of the steel.
As in the case of hot-rolled steel, Mo can be used instead of W of T1 grade, which leads to the development of M2 type (6-5-4-2), which can replace T1 for most purposes.
Another variant is M7, which has a higher Mo content but less w than m2. For some applications, M7 is said to have greater toughness and wear resistance than m2. Like T1, both m2 and M7 can be alloyed with CO to improve thermal wear resistance. This variant of M7 is named M42, and the suitable hardening temperature for m steel is 1200-1220 ℃; sometimes 1230 ° C is the high hardening temperature, which should not be exceeded in any case.
On 2018-08-08 11:45:46
