锻后余热代替正火对 S355 锻材组织和性能的影响

Effect of Residual Heat Replacing Normalizing after Forging on Microstructure and Properties of S355 Forging Materials

为节约S355锻材生产成本、提高生产效率,根据客户提出的S355正火锻材组织和力学性能要求,提出一种用锻后余热代替正火,研究空冷、风冷、水冷工艺对组织、力学性能的影响,利用光学显微镜对不同热处理工艺下试验钢的显微组织进行观察,并且利用拉伸和冲击试验机对试验钢的力学性能进行了测定。结果表明,余热+空冷或风冷热处理工艺组织为铁素体+珠光体;余热+水冷热处理工艺组织为铁素体+贝氏体+少量珠光体,组织不合;三种热处理制度下力学性能都能满足客户需求,φ450mm锻材80mm处屈服可达≥300MPa以上,低温冲击达97J以上。

In order to save the production cost and improve the production efficiency of S355 forging steel bars,according to the customer's requirements on the microstructure and mechanical properties of S355 normalized forging bars,a new method of using waste heat after forging instead of normalizing was proposed.The effects of air cooling,forced air cooling and water cooling processes on the microstructure and mechanical properties of the test-ed steel were studied.The microstructure of the tested steel under different heat treatment processes was observed by optical microscope.The mechanical properties of the tested steel bars were measured by tensile and impact testing machines.The results show that the microstructure of waste heat+air cooling or forced air cooling heat treatment process are ferrite+pearlite;the microstructure of waste heat+water cooling heat treatment process are ferrite+bainite+a small amount of pearlite,and the microstructure is unqualified;the mechanical properties of the three heat treatment systems can meet the needs of customers,the yield at 80mm ofφ450mm forging bars can reach more than 295MPa,and the low temperature impact can reach more than 97J.