热处理工艺对304不锈钢管胀管性能的影响

Effect of heat treatment on expanding of 304 stainless steel tube

研究304不锈钢管胀管过程中热处理工艺对焊缝的表面裂纹、显微组织及弯曲力学性能的影响。结果表明,304不锈钢焊管最佳热处理工艺为:850℃保温预热1 h,升温到1050℃保温2 h出炉水冷,340℃回火1 h空冷,经过热处理的不锈钢管胀管开裂率降低到了3%;增加预热处理有利于焊缝组织的充分转变,热处理后焊缝的显微组织为柱状奥氏体和完全奥氏体化的母材,焊缝与母材熔合区组织不均匀已经消除;热处理态的不锈钢管胀管表面的裂纹短而浅。

The effect of heat treatment process on surface crack, microstructure and bending mechanical properties of welding seam of 304 stainless steel tubes was studied during expanding process. The results show that the optimal heat treatment process is preheating at 850 ℃ for 1 h, rising to 1050 ℃ and holding for 2 h, cooled by water, followed by tempering at 340 ℃ for 1 h and cooled by air. Crack rate of expanded tubes treated by this heat treatment process decreases to 3%. The preheating is helpful for the full transformation of the welding seam microstructure which is fully austenitic of columnar austenite and substrate. Structure inhomogeneity of the welded joints between welding seam and substrate is disappeared. After heat treatment, crack of expand tubes surface is shallow and short.