(1) expand the range of applications of GCr15 steel, general the GCr15 steel M quenching ferrule effective wall thickness 12mm, BL quenching ability of nitrate cooling, stirring, string action, add water, and other measures, the ferrule effective wall thickness can be extended to about 28mm.
(2) hardness, good uniformity BL change is a slow process, generally GCr15 steel need 4h the steel GCr18Mo need 5h ??rings nitrate in for a long time isothermal surface the heart organized by the Ministry of transition almost simultaneously, hardness and stability , good uniformity, ships GCr15 steel the BL after quenching hardness of 59 to 61HRC uniformity ≤ 1HRC, and not like quenching ferrule wall thickness slightly larger low hardness, soft spots, poor uniformity problems.
(3) to reduce quenching, grinding cracks in the railway, rolling mill bearings production, the ferrule size, weight, the oil quenching M organization brittleness, high hardness after quenching the often take strong cooling measures, resulting in quenching the micro cracks; BL quenching BL organization Resilience better organized than M, while the surface up to -400 to 500 MPa of the compressive stress is formed, and greatly reduces the tendency to crack quenching; grinding surface compressive stress offset part of the grinding stress, so that the overall decline in stress levels, greatly reducing the grinding cracks.
(4) bearing service life by rail to withstand large impact loads, rolling mill bearings, quenched by M main failure mode: assembling sets of cracks within the course of the impact of the outer ring wall off the block, the inner ring fragmentation, while the isothermal quenching bearings due to the impact toughness, surface compressive stress, regardless of the assembly sets of cracks within the process of using the jacket wall off the block, within the set of fragmentation tendency is greatly reduced, and the lower edge of roller stress concentration.
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