深冲用SPHC钢开裂原因分析及改进措施

针对某厂生产的SPHC热轧酸洗卷在制作压缩机壳体过程中出现了制耳甚至开裂的现象，对其产生原因进行了研究。结果表明，SPHC低碳钢的Ar3温度较高，而终轧温度偏低，导致其在两相区轧制且带钢长度和宽度方向温度不均，使SPHC带钢产生混晶或粗晶组织，这是产生深冲开裂和制耳的主要原因。为此，提出了工艺改进措施，如提高加热温度、减少除鳞水；增加中间坯厚度、提高穿带和轧制速度、加盖保温罩、采用热卷取箱等，以保证薄规格SPHC带钢的终轧温度不小于910 ℃且改善带钢温度均匀性。生产实践表明，采用改进措施后，显著提高了薄规格SPHC带钢深冲性能，开裂率由30%降低至3‰。

Causes analysis and improvement measures of cracking of SPHC strip for deep drawing

Aiming at the problems of appearing ears and crack of the SPHC hot rolled and pickled coils produced by a factory during the process of making the compressor shell,the causes were studied.The results show that SPHC low carbon steel strip is rolled in two phase zone because of its high Ar3 temperature and low finishing rolling temperature, and the temperatures of length and width direction of strip are not uniform,which caused mixed grain or coarse grain microstructure and lead to the defects.Therefore,some improvement measures were put forward,such as increasing the heating temperature and reducing descaling water,increasing the thickness of the intermediate slab,increasing the threading and rolling speed,covering the heat insulation cover,using a hot coiling box,etc.,to ensure finishing rolling temperature was not less than 910 ℃ of thin gauge SPHC strip,and the temperature uniformity of the strip was improved.Production practice shows that the deep drawing performance of thin gauge SPHC strip is significantly improved,and the cracking rate is reduced from 30% to 3‰ after adopting the improvement measures.