CARBURIZED STEEL PART HAVING EXCELLENT LOW CYCLE BENDING FATIGUE STRENGTH
A carburized steel part having excellent low cycle bending fatigue strength which is comprised of a steel material which contains, by mass %, C: 0.1 to 0.6%, Si: 0.01 to 1.5%, Mn: 0.3 to 2.0, P: 0.02% or less, S: 0.001 to 0.15%, N: 0.001 to 0.03%, Al: 0.001 to 0.06%, and O: 0.005% or less and has a balance of substantially iron and unavoidable impurities and which is carburized and quenched, and then tempered, which steel part has a surface hardness of HV550 to HV800 and a core hardness of HV400 to HV500.
1 . A carburized steel part having excellent low cycle bending fatigue strength which is comprised of a steel material which contains, by mass %,
C: 0.1 to 0.6%,
Si: 0.01 to 1.5%,
Mn: 0.3 to 2.0%,
P: 0.02% or less,
S: 0.001 to 0.15%,
N: 0.001 to 0.03%,
Al: 0.001 to 0.06%, and
O: 0.005% or less and has
a balance of substantially iron and unavoidable impurities and
which is carburized and quenched, and then tempered,
said steel part characterized in that
it has a surface hardness of HV550 to HV800 and a core hardness of HV400 to HV500.
2 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said low cycle bending fatigue strength is 20 kN or more.
3 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, B: 0.0002 to 0.005%.
4 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel further contains, by mass %, Cr: 1.20 to 3.0%.
5 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, Ti: 0.01 to 0.2%.
6 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, one or more of Mo: less than 0.1%, Cu: less than 0.1%, and Ni: less than 0.1% as unavoidable ingredients.
7 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, one or more of Mo: 0.1 to 1.5%, Cu: 0.1 to 2.0%, and Ni: 0.1 to 5.0%.
8 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, one or both of Nb: 0.01 to 0.2% and V: 0.03 to 0.2%.
9 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said steel material further contains, by mass %, one or more of Ca: 0.0002 to 0.005%, Zr: 0.0003 to 0.005%, and Mg: 0.0003 to 0.005%.
10 . A carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , characterized in that said carburized steel part is a differential gear or transmission gear.