It is shown that the Persian Kurdistan bulat steel blades (end of the XVIII century) correspond with respect to chemical composition to contemporary high-carbon steel (1.48 and 1.67% C), with a high content of phosphorus impurity (0.192 and 0.236% P). However, contemporary industry carbon tool steels are not used with this carbon and phosphorus content. It is revealed that the main distinguishing feature of ancient bulat steels from modern tool steels is layered heterogeneity with respect to composition, structure, and hardness distribution. Layered carbide heterogeneity develops in the form of patterns after polishing and etching in 3% alcoholic nitric acid solution. It is found that the carbide layers located in a troostite matrix consist of oblong shaped cementite with a 1/3 ratio of axes. The microhardness of carbide layers is determined in the range of values from 820 to 1020 HV . In troostite layers the range of microhardness values is from 390 to 560 HV . The layered distribution of microhardness in the edge of a bulat blade is a micro-saw with teeth from 50 to 100 microns. Tests for cutting edge resistance on cutting felt in a unit with a reciprocating mechanism are carried out. It is revealed that with low cutting forces (up to 40 N) bulat steel withstands a greater number of cuts than carbon tool steel with a uniform structure. With an increase cutting edge force from 6 to 12 kg bulat steel type Ds15P demonstrated 30% fewer cuts than by carbon tool steel type Y15А. It has been established that within the layered structure of bulat steel fatigue crack propagation from the instant of its occurrence to complete destruction occurs in a greater number of cycles than in the homogen eous structure of carbon tool steel. Old blades of bulat steel type Ds15P according to fatigue life indices show twice as long life compared to modern carbon tool steel type Y15А. Loss of cutting capacity is compensated by an increase in blade “viability” with repeated fatigue loads. Thermal tests are conducted for the impact strength of genuine bulat steel type Ds17P. It is shown that in the temperature range from 0 to +40°C impact strength increases by a factor of four. It is established that chemical and structural layering of bulat steel minimizes the negative impact of phosphorus impurities, and impact energy at failure increases by 35%.

中文翻译：

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十八世纪波斯布拉特钢与现代工具钢相比的机械性能

结果表明，波斯库尔德斯坦布拉特钢刀片（十八世纪末）在化学成分方面与当代高碳钢（1.48% 和 1.67% C）相对应，磷杂质含量高（0.192% 和 0.236% P） ）。然而，当代工业碳工具钢不使用这种碳和磷含量。结果表明，古代布拉特钢与现代工具钢的主要区别在于成分、结构和硬度分布方面的层状不均匀性。在 3% 的硝酸酒精溶液中抛光和蚀刻后，层状碳化物异质性以图案的形式发展。发现位于屈氏体基体中的碳化物层由具有1/3轴比的长方形渗碳体组成。碳化物层的显微硬度在 820 到 1020 HV 的范围内确定。在屈氏体层中，显微硬度值的范围为 390 至 560 HV。bulat 刀片边缘显微硬度的分层分布是一种锯齿从 50 到 100 微米的微型锯。在带有往复机构的装置中进行切割毛毡的切割边缘阻力测试。结果表明，在低切削力（高达 40 N）的情况下，bulat 钢比具有均匀结构的碳工具钢能够承受更多的切削次数。随着切削刃力从 6 公斤增加到 12 公斤，Ds15P 型 bulat 钢比 Y15А 碳工具钢减少了 30% 的切削量。已经确定，在 bulat 钢的层状结构中，从其出现的瞬间到完全破坏，疲劳裂纹扩展的循环次数比碳工具钢的均质结构中发生的循环次数多。与现代碳工具钢 Y15А 相比，根据疲劳寿命指数，Blat 钢 Ds15P 型旧刀片的寿命是其两倍。切割能力的损失通过重复疲劳载荷增加刀片“活力”来补偿。对真正的布拉特钢 Ds17P 的冲击强度进行了热测试。结果表明，在 0 到 +40°C 的温度范围内，冲击强度增加了四倍。已确定 bulat 钢的化学和结构分层可最大限度地减少磷杂质的负面影响，