Rundstål 42CrMoS4+M/2244M

2244M/42CrMo4 is a low-alloy (chrome-molybdenum) quenched-and-tempered (QT) steel with medium carbon content. Machinability is enhanced through M-treatment. In comparison with 2225M/25CrMo4, the strength level for a given dimension is higher for 2244M/42CrMo4 at the same time as an acceptable combination of strength and toughness is achievable to larger diameters.

Tibnor has chosen to stock QT-bars which conform to the requirements for hardness and strength in the (discontinued) Swedish standard 2244. The mechanical properties are equivalent to or better than for steel 42CrMo4 in SS-EN ISO 683-2. In concurrence with 42CrMo4, 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 42CrMo4 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 2244M/42CrMo4.

In Tibnor’s stock-standard programme for 2244M, diameters >20 mm are for the most part peeled but some heavier bars are as-hot-rolled. Dimensions 10-20 mm are cold drawn and the relevant standard is then SS-EN 10277 - 5 with conditions “+QT” and “+C” (cold-drawn). The cold-drawn diameter tolerance is h10 (ISO 286-2).

Welding of 2244M is not to be recommended. The steel is weldable but must be pre-heated to a high temperature and parts should preferably be quenched-and-tempered again after welding. 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, 2244M responds well to surface hardening by both induction hardening and nitriding.