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Rundstål 25CrMoS4+M (2225M)
2225M/25CrMo4 is a low-alloy (chrome-molybdenum) quenched-and-tempered (QT) steel with relatively low carbon content. Machinability is enhanced through M-treatment. The steel is supplied in a QT-condition rendering further heat treatment unnecessary.
Tibnor has chosen to stock QT-bars which conform to the requirements for hardness and strength in the (discontinued) Swedish standard 2225. The mechanical properties are equivalent to or better than for steel 25CrMo4 in SS-EN ISO 683-2. In concurrence with 25CrMo4, the guaranteed levels for yield strength, tensile strength and hardness decrease as the dimension increases even if the levels are fixed over stipulated diameter intervals. At variance with 25CrMo4 in SS-EN ISO 683-2, the impact strength is guaranteed to 27J better at -20°C. For complete information on the mechanical properties which apply for a given bar dimension, please consult Tibnors Stålvalsguide or the data sheet for 2225M/25CrMo4.
In Tibnor’s stock-standard programme for 2225M, diameters >20 mm are peeled whereas those
10-20 mm are cold drawn. In the latter execution, the relevant standard is SS-EN 10277 - 5 with conditions “+QT” and “+C” (cold-drawn). The cold-drawn diameter tolerance is h10 (ISO 286-2).
The carbon content in 2225M is relatively low so the steel is weldable even if pre-heating is to be recommended unless parts are very small. Machining of QT-steels is generally considered troublesome but there is a pronounced enhancement of machinability thanks to the M-treatment.
If the application requires a wear-resistant surface, 2225M responds well to surface hardening by both induction hardening and nitriding. If needed, the steel can also be case hardened.