低合金冷作模具鋼中組織缺陷主要有:網狀碳化物、碳化物呈帶狀偏析、碳化物液析。下面來詳細講講相關內容吧。

The main structural defects in low alloy cold working die steel are network carbide, band segregation of carbide and liquid segregation of carbide. Let's talk about the relevant contents in detail.

1.現現網狀碳化物，是由于鋼材在軋制或鍛造成形時，停軋或停鍛溫度較高而冷卻速度過緩，二次碳化物沿奧氏體晶界呈網狀析出，有時還會出現魏氏組織的碳化物，呈針狀伸入晶內。

1. The present network carbides are due to the slow cooling rate due to the high stop rolling or stop forging temperature when the steel is rolled or forged. The secondary carbides are precipitated in a network along the austenite grain boundary, and sometimes the carbides of Widmanstatten structure may appear, which extend into the crystal in a needle shape.

2.碳化物呈帶狀偏析，是由于鋼錠冷卻時，微觀結晶出現偏析，在樹枝晶之間的后凝固區域，富集著碳和鉻等溶質元素，凝固后析出聚集著大量碳化物，在鍛軋過程中它逐步沿熱加工方向延伸成帶狀。

2. The carbide is banded segregation, which is due to the segregation of the micro crystal during the cooling of the ingot. In the post solidification area between the dendrites, solute elements such as carbon and chromium are enriched. After solidification, a large number of carbides are precipitated and accumulated. During the forging and rolling process, it gradually extends into a band along the hot processing direction.

3.碳化物液析，是由于鑄錠在冷卻時會出現元素偏析，在后凝固區溶質含量高，形成碳及合金元素的富集區，當在晶界附近成分達到共晶成分時，凝固后會出現共晶萊氏體。這種亞穩定的共晶萊氏體在緩慢冷卻的過程中，或在軋制加熱時會形成離異共晶，離異出來的碳化物，經軋制后，呈白色多角狀碎塊沿軋制方向分布成鏈狀或帶狀，常出現于鋼材的中心地帶。

3. Carbide liquidus is due to element segregation of ingot during cooling, high solute content in post solidification zone, forming enrichment zone of carbon and alloy elements. When the composition near the grain boundary reaches eutectic composition, eutectic ledeburite will appear after solidification. This metastable eutectic ledeburite will form divorced eutectic in the process of slow cooling or during rolling heating. After rolling, the separated carbides will be white polygonal fragments distributed in chains or bands along the rolling direction and often appear in the center of the steel.

此外低合金冷作模具鋼中組織出現網狀碳化物、碳化物呈帶狀偏析、碳化物液析等缺陷，導致模具在服役時出現工作面剝落、崩刃或開裂。也給模具的熱處理帶來不利的影響，往往會造成模具在淬火時出現淬裂。

In addition, the structure of low alloy cold working die steel has defects such as network carbide, band segregation of carbide and liquid segregation of carbide, which lead to the working surface peeling, edge collapse or cracking of the die during service. It also has an adverse effect on the heat treatment of the mold, often causing the mold to crack during quenching.

1.網狀碳化物的方法，是采用正火處理

1. The method of eliminating network carbide is normalizing

2.碳化物呈帶狀偏析的方法，是對鋼材重新進行合理鍛造，鍛造后控制冷卻或鍛造后淬火處理，熱處理時再采用固溶雙細化處理工藝。也可以根據偏析程度，直接采用固溶雙細化處理工藝。

2. The method to eliminate the banded segregation of carbides is to re forge the steel reasonably, control the cooling after forging or quench after forging, and then adopt the solid solution double refining process during heat treatment. According to the degree of segregation, the solid solution double refining process can also be directly adopted.

3.碳化物液析的方法，是采用擴散退火處理，或固溶+急冷處理，或鍛造后利用余熱進行淬火處理。

3. The method to eliminate carbide precipitation is diffusion annealing treatment, solid solution + quenching treatment, or quenching treatment with residual heat after forging.

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