S32750无缝钢管冷轧开裂原因分析及控制

Investigation of Causes for Cracking of S32750 Seamless Steel Tube during Cold-rolling Process and Relevant Control Measures

通过工艺分析和理化检验,探讨了S32750无缝钢管冷轧开裂产生的具体原因,排除了冷轧工艺及夹杂物对开裂现象的影响,提出了金属间相是造成开裂的主要原因。金属间相是在热挤压过程中产生的,且在热挤压过程中无法避免,需通过后续的固溶工序消除。不同工艺的固溶试验结果表明:S32750无缝钢管热处理最佳固溶温度为1 100℃,保温时间为(壁厚×2)min;此时,既可以保证析出相全部溶解,同时钢管也可以顺利冷轧,并具备优异的组织性能。

Investigated are the specific causes for cracking of the S32750 seamless steel tube during cold-rolling process by means of relevant process analysis and physiochemical tests. Accordingly, it is concluded that the cold- rolling process itself and the inclusions produce no influences on the cracking, whereas the intermetallic phase plays a major role in developing the cracking. The intermetallic phase is formed during the hot-extrusion process, and it is by no means avoided, and can only be eliminated by the subsequent solid solution process. The results from the solid solution tests of different processes demonstrate that the best solid solution temperature for the S32750 seamless steel tube is 1 100 ℃, and the holding time is （W.T.×2）min. In this case, it is ensured that the precipitated phases are completely dissolved, while the tube can be cold-rolled smoothly, and finally possesses excellent micro structure.