一、在外部冷却液的急冷条件下(即使是空冷)，表面已奥氏体化的薄层又重新进行第二次悴火，形成高硬度的二次淬火组织，即“磨削白层”。使之形成一层硬度较低的黑色“过回火层”，此时体积收缩，这样在磨削表面层内就产生了较高的温度梯度，从而引起一系列组织变化和力学性能的变化."磨削白层”系处于压应力状态。

二、而“过回火层”则处于Zui大的拉应力状态，因此裂纹核心Zui容易在此萌生，尤其是“磨削白层”与‘过回火层，的交界面上，因为这里是组织变化Zui明显突变处，拉应力Zui集中，强度Zui弱，当残余拉应力值大于材料的抗破断强度时，裂纹就向半径方向扩展，使表层出现断裂，即磨削裂纹。

三、次淬火白层组织的特征：由于白层是一种奥氏体、马氏体和碳化物共存的多相高弥散组织.奥氏体与马氏体之间存在着共格的伪平衡系统以及晶格常数有差异，所以形成马氏体时，二次奥氏体的点阵发生强烈暗变，这就导致了白层组织硬度的增高。又因奥氏体-马氏体界面上的表面能趋于零，在腐蚀剂的作用下，组织上不产生电化学的原电池，故白层难于腐蚀，只不过它是在磨削条件下形成的白层

四、钢材质量和淬回火组织质量对诱发磨削裂纹的影响,淬回火状态时马氏体基体黑白浓度差，较高的宏观硬度值及疏松缺陷等，也是诱发磨削裂纹的一个不可忽视的潜在因素。黑白浓度差的出现表明原始组织中存在严重的带状碳化物，由此引起带上与带间的碳格浓度的偏析，因此淬火后增大了带间的过热倾向和Ms点高低之差别，

五、造成淬火组织和残余应力的分布不均匀性及增加基体脆性，削弱了晶粒与晶粒、晶粒与基体、以及基体与基体之间的接合力.尽管套圈已经过低温油回火，但由于回火不充分或该马氏体基体在该条件下回火，其抗回火性高的原因，以致淬火马氏体回火转变不完全，力士乐叶片泵仍保持高硬度、高内应力的淬火状态。

六、这些因素均有利于磨削应力集中，不易分散，易与基体残余应力叠加，特别是在超级别带状碳化物上伴随有网状、条状碳化物时，则磨削应力Zui易集中，促使零件表面形成剥落及分散分布的条状与残余网络状龟裂。明显的疏松缺陷在成品轴承套圈上是不容许存在的。

七、它会降低套圈的致密度，使内部富集较多的微孔隙，低熔点杂质，气体和非金属夹杂物.它与带状碳化物一样，起到分割基体连续性作用，造成成分偏析，基体致脆，大大降低套圈的综合力学性能，而且磨削时增大摩擦阻力和缺口敏感性，促使磨削应力高度集中，极易诱发磨削裂纹。

德国Rexroth力士乐比例阀

原装，质量保证，部分型号现货 

DBETX-1X/180G24-25NZ4M-36  DBETX-1X/25G24-25NZ4M-36

DBETX-1X/350G24-25NZ4M     DBETX-1X/50G24-8NZ4M

DBETX-1X/250G24-25NZ4M     DBETX-1X/50G24-25NZ4M

DBETX-1X/315G24-25NZ4M     DBETX-1X/180G24-25NZ4M

DBETX-1X/80G24-25NZ4M      DBETX-1X/250G24-8NZ4M-34

DBETX-1X/250G24-8NZ4M-35   DBETX-1X/180G24-8NZ4M-34

DBETX-1X/250G24-25NZ4M-39  DBETFX-1X/80G24-27NZ4M

DBETFX-1X/180G24-27NZ4M    DBETFX-1X/250G24-27NZ4M

DBETFX-1X/315G24-27NZ4M    DBETX-1X/250G24-8NZ4M

DBETX-1X/80G24-8NZ4M       DBETX-1X/315G24-8NZ4M

DBETBX-1X/80G24-16Z4M      DBETBX-1X/230G24-16Z4M

DBETBX-1X/28G24-37Z4M      DBETBX-1X/25G24-16Z4M

DBETBX-1X/80G24-37Z4M-38   DBETBX-1X/315G24-37Z4M-38

DBETBX-1X/315G24-37Z4M     DBETBX-1X/250G24-37Z4M-38

DBETBX-1X/315G24-16Z4M     DBETBX-1X/180G24-16Z4M-37

DBET-6X/420G24K4V          DBET-5X/350G24K4V-1

DBETE-6X/420YG24K31A1V     DBETE-6X/200G24K31A1M

DBET-5X/150G24K4M-32       DBET-6X/100YG24K4V

DBET-6X/315YG24K4V         DBET-6X/350YG24K4V

DBET-6X/50YG24K4V          DBETE-6X/350YG24K31A1V

DBETE-6X/100YG24K31A1V     DBETE-6X/50YG24K31A1V

DBETE-5X/100YG24K31M-1     DBETE-6X/50G24K31A1V=DE

德国Rexroth力士乐比例阀

原装，质量保证，部分型号现货 

DBETE-6X/350G24K31F1V      DBETE-6X/50G24K31F1V

DBETE-6X/250G24K31A1V      DBETE-5X/100G24K31M-1

DBET-6X/350G24K4V          DBET-6X/315G24K4V

DBET-6X/200G24K4V          DBET-6X/100G24K4V

DBET-6X/50G24K4V           DBET-5X/350YG24N9K4V-1

DBET-3X/50YG24K4           DBETE-5X/200G24K31V

DBET-5X/200G24K4M-27       DBET-5X/200G24K4V-21

DBETE-5X/350YG24K31M-1     DBET-5X/200G24N9K4M-1

DBET-5X/315G24K4M-27       DBET-5X/350G24K4M-27

DBETE-5X/315G24K31V-27     DBETE-5X/350G24K31M-27

DBETE-5X/315G24K31M-27     DBET-5X/200G24K4V-27

DBET-5X/200G24NK4V         DBET-5X=315G24K4M=DE

DBETE-5X=50G24K31M=DE      DBETR-1X=80G24K4M=DE

DBETRE-2X=180G24K31A1M=DE  DBETR-1X=180G24K4M=DE

DBET-3X/315YG24K4V         DBETRE-2X/315G24K31A1M

DBETRE-2X/250G24K31A1M     DBETRE-2X/180G24K31A1M

DBET-5X/400G24NK4M-8       DBET-5X/50G24K4M-1

DBETE-5X/200YG24K31M-1     DBETRE-2X/80G24K31A1M

DBETE-5X/315G24N9K31M-1    DBET-3X/315G24K4V

DBET-3X/50G24K4            DBETE-5X/200G24K31M-1

DBET-5X/400G24N9K4M-8      DBET-5X/100G24K4M-1

DBET-5X/315G24NK4V-1       DBETE-5X/350G24NK31M

DBET-3X/315G24K4           DBET-5X/200YG24N9K4M-1

德国Rexroth力士乐比例阀

原装，质量保证，部分型号现货 

DBET-3X/50G24NK4-271       DBET-5X/100G24NK4M-1

DBET-5X/350YG24NK4M-1      DBET-5X/50G24K4V

DBET-5X/50G24NK4V          DBETE-5X/350G24K31M

DBETR-1X/30G24K4M          DBETE-5X/200G24NK31M-1

DBET-5X/350G24N9K4M        DBET-5X/100YG24K4M-1

DBET-5X/100G24K4M          DBET-5X/315G24N9K4M

DBET-5X/350G24NK4V         DBETE-5X/100G24NK31M-1

DBETE-5X/315YG24NK31M-1    DBETE-5X/350G24K31V

DBET-5X/315G24K4V          DBET-5X/400YG24NK4M-14

DBETE-5X/200G24K31M        DBETE-5X/315G24NK31M

DBET-5X/350G24K4M-1        DBET-5X/400YG24N9K4M-8

DBETE-5X/350G24NK31M-1     DBET-5X/350G24NK4M-1

DBET-5X/315G24NK4M-1       DBET-5X/400YG24K4M-8

DBET-5X/350YG24N9K4M-1     DBET-5X/350YG24K4M-1

DBET-5X/315G24K4V-1        DBETE-5X/315G24K31M

DBET-3X/315G24K4-152       DBETE-5X/315G24K31M-20

DBET-5X/200G12K4M-1        DBET-5X/315G12K4M-1

DBET-5X/100YG24NK4M-1      DBET-5X/350G24K4M

DBET-5X/315G24NK4M         DBET-5X/100G24NK4V

DBET-5X/50G24NK4M          DBET-5X/200G24NK4M

DBET-5X/350G24NK4M         DBET-5X/400G24K4M-8

DBETR-1X/350G24K4M-437     DBET-5X/315YG24NK4M-1

DBET-5X/315G24N9K4M-1      DBETE-5X/200G24NK31M

德国Rexroth力士乐比例阀

原装，质量保证，部分型号现货 

DBET-5X/200G24K4M-1        DBET-5X/200G24N9K4M

DBET-5X/100G24NK4M         DBET-5X/200G24K4M

DBET-5X/50G24K4M           DBETE-5X/350G24K31M-1

DBETR-1X/230G24K4M-677     DBET-5X/315YG24NK4V-1

DBETRE-2X/30G24K31A1M      DBET-5X/200G24K4V

DBETE-5X/315G24K31V        DBETRE-2X/350G24K31A1M

DBET-5X/100G24K4M-27       DBET-5X/400YG24K4M-14

DBETE-5X/100YG24NK31M-1    DBETE-5X/200YG24NK31M-1

DBET-5X/50YG24K4M-1        DBET-5X/200G24K4V-22

DBETR-1X/315G24K4M-437     DBETR-1X/315G24K4V-409

DBETR-1X/180G24K4M-437     DBETR-1X/230G24K4M

DBETR-1X/315G24K4M-409     DBETR-1X/180G24K4M-409

DBETR-1X/315G24K4M-381     DBETR-1X/350G24K4M

DBETB-1X/80G24K4M          DBETB-1X/230G24K4M

DBETR-1X/180G24K4V         DBETR-1X/80G24K4M

DBETR-1X/315G24K4V         DBET-3X/200G24K4

DBETR-1X/350G24K4V-437     DBETRE-2X=180G24K31A1M-1=DE

德国Rexroth力士乐比例阀

原装，质量保证，部分型号现货 

DBEME20-5X/50YG24K31M    订货号：R900954711

DBEME20-5X/350YG24K31V   订货号：R900937596

DBEME20-5X/350YG24K31M   订货号：R900954710

DBEME20-5X/315YG24K31M   订货号：R900536813

DBEME20-5X/315XYG24K31M  订货号：R900901375

DBEME20-5X/200YG24K31M   订货号：R900954709

DBEME20-5X/100YG24K31M   订货号：R900937307

DBEME20-5X/100XYG24K31M  订货号：R900717759

DBEM20-5X/50YG24NK4M     订货号：R900922698

DBEM20-5X/50YG24K4M      订货号：R901114837

DBEM20-5X/350YG24K4V     订货号：R900709844

DBEM20-5X/350YG24K4M     订货号：R900578827

DBEM20-5X/315YG24K4M-1   订货号：R900916130

DBEM20-5X/315YG24K4M     订货号：R900923241

DBEM20-5X/315XYG24K4M-1  订货号：R900962811

DBEM20-5X/315XYG24K4M    订货号：R900727879

DBEM20-5X/200YG24NK4M    订货号：R900916129

DBEM20-5X/200YG24K4V-1   订货号：R900941260

DBEM20-5X/200YG24K4M-1   订货号：R900579947

DBEM20-5X/200YG24K4M     订货号：R900923239

DBEM20-5X/200XYG24K4M-1  订货号：R900941302

DBEM20-5X/100YG24K4M     订货号：R900916127