结果表明，导致密封圈变形而破裂的原因是选用的ST12钢含碳量太低，应选用含碳量和强度稍高的材料来制造。
The result shows the reason why sealing washer parts destroyed is that carbon content of ST12 steel used is too low. High carbon content and strength material should be used to produce the parts.
含碳量低的钢对淬火处理没有明显的反应。
Steel with low carbon content will not respond appreciably to hardening treatment.
随着钢的含碳量增加到大约0.60%，可能得到的硬度也增加。
As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases.
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