Application of “soft canning” heat preservation technique in the superalloy forging process

Baosteel Technical ResearchVolume 5 ,Number 4 ,December 2011 ,Page 21Application of“soft canning”heat preservation technique inthe superalloy forging processWANG Zixing”, CHEN Guosheng' , ZHOU Dianhua?) and WANG Qingzeng21) Special Steel Technology Center, Research Institute, Baoshan Iron & Steel Co, Ltd, Shanghai 200940, China2) Special Steel Business Unit, Baoshan lron & Steel Co, Ltd, Shanghai 200940, ChinaAbstract: The“soft canning ”heat preservation technique is invented by Baoshan Iron & Stee! Co. , Ltd. ( Hereafterreferred to Basteel) ,using the flexible insulation material which can be stuck on the surface of the heated ingot or billetin the superalloy thermal process. This adhesive insulation material can reduce the temperature drop of the ingot or billetduring the transferring or hot working process , and can deform with the billet without dropping. The surface temperaturedrop can be effectively reduced ,so the products can be obtained a good surface quality and the structural uniformity can beimproved. The technique is applied to hard-wrought superalloy forging of cogging，superalloy rods finished forging fire andsuperalloy hot die forging processing , and good results have been achieved.Key words: soft canning; superalloy; heat preservation forgingdoi: 10. 3969/j. issn. 1674 - 3458. 2011.04.005working temperature range of lower than 50C.1 IntroductionCompared with the traditional “ hard canning ，insulation technique, the“ soft canning ”insulation-Superalloy has a strong resistance to deformation ,technique can be simply carried out, has effectivewhereas the temperaturee range of thermal processing isinsulation results, generates significant benefits andnarrow. So the key question of superalloy thermalpossesses other obvious advantages. Compared with theprocessing is if the thermal process of the ingot or thetraditional multiple small deformations forging process,billet under enough deformation can be controlled at anthis technique can increase the degree of a single fireoptimum temperature range. Therefore,it is necessarydeformation, uniformity of macrostructure or micro-to minimize the temperature drop of the billet or thestructure and reduce the energy consumption and so on.ingot because of the transfer and heat absorption ofCurrently, the“soft canning ”insulation technique isforging tools in the forging process ，especially theapplied to the hard-wrought superalloy thermal pro-cesssurface. Some of the effective methods are frequentlyof rapid forging ,radical forging and hot die forging.returming to the furnace ,or taking insulation measures.Traditional“hard canning ”insulation technique hassome insulation effect-conventionally ，the ingot or billet2 Application and results of the “softis wrapped with insulating cotton covered by alloy sheetscanning”heat reservation forging techniqueduring heating and forging. However, the operation israther complicated ( which needs to wrap up and remove2. 1 Application of hard-wrought superalloy coggingthe sheets for each fire), and it is difficult to detectWhen the technique is applied to superalloy coggingforging defects and other issues during the forgingforging ,the cold deformation zone on the surface afterprocess. To solve the problem of forging hard-wroughtforging is significantly reduced due to the reduction ofsuperalloy , Baosteel Special Steel has invented the“softtemperature drop of the surface.canning”heat preservation technique.The macrostructure of IN718-modified alloy φ250 mmThe“soft canning”heat preservation technique isbillts after cogging forging by“soft canning”forgingbased on a flexible adhesive insulation material whichand traditional forging respectively are shown inis invented by Baosteel Special Steel and has goodFig.1. The melting process of the alloy is vacuumlubrication and adhesive properties. The material can beinduction melting ( VIM) + vacuum arc remeltingdirectly stuck onto the surfaces of either cold or hot( VAR) , and the ingot dimension is φ423 mm. Afterbillets for heating or forging. This adhesive insulationhomogenization the VAR ingot was forged into billetsmaterial can reduce the temperature drop of the ingotby hydraulic press, and the amount of deformationor billet during the transferring or hot working process,was the same. There are some suspected remainingand can deform with the billet without dropping. Thecast features中國煤化工by_ traditionalsoft canning technique is suitable for cogging andforging , buti ively uniformforming of some hard-wrought superalloys with hotby“soft cann:MYHCNMHGCorresponding author: WANG Zixing; E-mail: wangzixing@ basteel. com.24Baosteel Technical Research, Vol. 5, No.4, Dec. 2011(4) Compared with the traditional “ hard canning”3 Conclusionstechnique, the“ soft canning ”technique issimple ,economical and effective.(1) When the technique is applied to coggingforging ,the cold deformation zone on the surfaceafterforging is significantly reduced due to the reduction ofsurface temperature drop. The hard-wrought superalloyssuch as GH742 and GH141 can achieve a good surfacequality in the cogging and finished forging process.(2) The technique is applied to GH4169 and GH907superalloy rods finished forging， the degree ofdeformation at a relatively low temperature can beincreased, the cold deformation zone on the surfaceWANG ZixingCHEN Guosheng ZHOU Dianhuaafter forging is significantly reduced, a more uniformedge and center of the finished bar structure can beachieved.(3) The application of the“soft canning”techniquein the hot die forging of superalloy can greatly reducethe working temperature of the hot die arrangement,which makes it much easier to manufacture the hot diearrangement, and high-quality NC19FeNb, GHI05,GH720 superalloy hot die forgings have beenWANG Qingzengdeveloped.中國煤化工MYHCNM HG.