436L铁素体不锈钢换热板片的成形过程及分析

Forming Process and Analysis of 436L Ferritic Stainless Steel Heat Exchanger Plate

针对436L铁素体不锈钢换热板片冲压成形的开裂问题,通过Dynaform数值模拟分析和冲压成形试验,对两种典型波纹结构换热板片的成形特征进行研究,分析其成形过程中的成形极限和减薄率的演变规律,研究板片厚度和波纹参数(波纹法向节距)对裂纹位置及开裂程度的影响,探讨波纹法向节距对减薄率的影响。结果表明,436L铁素体不锈钢换热板片的开裂和减薄同时受板厚及波纹参数的影响。对于浅波纹换热板片(波纹深度2 mm),易开裂处为波纹的波峰圆角顶部,板厚增加对开裂倾向和减薄率影响显著,每增加0.1 mm板材厚度,波峰圆角处最大减薄率可降低约2.6%,此时,能够安全成形的最大减薄率为18.9%,最小成形板厚为0.6 mm。而对于深波纹换热板片(波纹深度2.6 mm),易开裂处为波纹的波峰圆角两侧和波峰圆角顶部,此时,板厚增加对开裂倾向和减薄率影响较小,每增加0.1 mm板材厚度,波峰圆角处最大减薄率仅降低约1.4%,需通过增大波纹法向节距满足成形质量要求。

In order to resolve the cracking problem of 436L ferritic stainless steel heat exchanger plates during stamping forming,the forming characteristics of two typical corrugated structure heat exchange plate were studied through Dynaform numerical simulation analysis and stamping forming experiments,the evolution of forming limit and thinning rate during the forming process was analyzed,and the influence of plate thickness and corrugation parameters(corrugation pitch)on crack location and degree of cracking was studied.Additionally,the impact of corrugation pitch on thinning rate was also discussed.The results indicate that the cracking and thinning of 436L ferritic stainless steel heat exchanger plates are both affected by plate thickness and corrugation parameters.For shallow corrugated heat exchanger plates(corrugation depth of 2 mm),the vulnerable area for cracking is the top of the corrugation's rounded corner.Increasing the plate thickness significantly affects the tendency for cracking and thinning rate,with a decrease of approximately 2.6%in the maximum thinning rate at the rounded corner for every 0.1 mm increase in plate thickness.At this point,the maximum safe thinning rate for forming is 18.9%,and the minimum forming plate thickness is 0.6 mm.For deep corrugated heat exchanger plates(corrugation depth of 2.6 mm),the vulnerable areas for cracking are the sides of the corrugation's rounded corner and the top of the rounded corner.Increasing the plate thickness has a smaller impact on the tendency for cracking and thinning rate,with only a decrease of approximately 1.4%in the maximum thinning rate at the rounded corner for every 0.1 mm increase in plate thickness.To ensure that the quality requirements for forming are met,it is necessary to increase the normal pitch of the corrugation.