9Cr18高压缸套生产工艺研究

Research on the process of high pressure cylinder sleeve 9Cr18

高压缸套需具备耐蚀性及承受高压,工作条件较为恶劣,9Cr18高碳、高铬不锈钢能够满足其使用要求,但该材料热加工性较差,锻造过程中及锻后均易发生开裂,且锻后组织易存在孪晶碳化物,影响其使用寿命及耐蚀性。锻前加热采用低温阶段缓慢升温、高温阶段快速升温,减少δ铁素体的形成,提高锻造塑性;锻造采用镦粗及分散小变形的方式,在上平砧、下V砧上拔长,破碎粗大的铸态组织及碳化物;锻后热处理采用球化退火,严控冷却速度,解决了退火组织中存在大量孪晶碳化物的难题,得到粒状珠光体组织,满足了高压缸套的使用要求。

High pressure cylinder sleeve requires corrosion resistance and can withstand high pressure. Under the extreme terrible working condition,stainless steel 9Cr18 of high carbon and high chromium can meet the demand of high pressure cylinder sleeve. However,its thermal processing performance is poor,and it is easy to crack during or after forging. In addition,it usually has twin carbide in the annealing microstructure that affects corrosion resistance and the service life of high pressure cylinder sleeve. Heating before forging was realized to reduce the formation of delta ferrite and improve the forging plasticity by a slowly heating at low heating stage and a rapid heating at high heating stage. The forging process was conducted by upsetting and small scattered deformation,and stretching was realized on the upper flat and lower V anvils to break cast structure and coarse carbide. By adopting the after forged heat treatment process of spheroidizing annealing and accurately controlling the cooling speed,the twin carbide existing in the annealing microstructure was eliminated. As a result,the granular pearlite was obtained which met the requirements of high pressure cylinder sleeve.