【摘要】：鐵基粉末冶金汽車減震器零部件在使用過程中受到交變載荷的作用,對(duì)包括疲勞強(qiáng)度在內(nèi)的綜合性能要求非常高,而高壓縮性鐵基基粉則是保證該類零部件產(chǎn)品具有優(yōu)良綜合性能的關(guān)鍵。安徽馬鋼粉末冶金有限公司采用現(xiàn)有還原鐵粉生產(chǎn)工藝制備的還原鐵粉的壓縮性一般低于6.80g/cm3,不利于粉末冶金制品的完全致密化燒結(jié),難以得到綜合性能優(yōu)異的粉末冶金汽車減震器結(jié)構(gòu)件。本文針對(duì)這一問題,從影響還原鐵粉壓縮性的一次還原溫度、二次還原溫度與氣氛、合批配料等方面入手,系統(tǒng)研究了上述幾個(gè)因素對(duì)還原鐵粉壓縮性的影響及控制關(guān)鍵,并將研究成果應(yīng)用于粉末冶金汽車減震器活塞。主要結(jié)論如下:1)隧道窯一次還原溫度最高為1160℃,相較于1120℃與1180℃,海綿鐵顆粒致密化程度高,孔隙度較小,分布均勻,化學(xué)成分純凈,且不會(huì)過燒,有利于后序二次還原及壓縮性能的提高;2)采用純氫氣替代氨裂解氣作還原氣氛,可充分脫碳、脫氧,并可防止鐵粉滲氮,提高鐵粉純度,可得到含鐵量高于99.0%的還原鐵粉,從而改善鐵粉壓縮性;3)精還原爐中的二次還原溫度最高為930℃,提高了鐵粉退火軟化效果,改善了鐵粉塑性,提高產(chǎn)品壓縮性能;4)配料比例為顆粒≥105μm約28~32%、≤75μm約50~54%,合批時(shí)間為28~30min時(shí),可以獲得壓縮性≥6.86g/cm3(500MPa壓力下)的高質(zhì)量還原鐵粉;5)以高壓縮性還原鐵粉為基粉,添加0.8%石墨和1.6%的300目銅粉制備的粉末冶金汽車減震器活塞的綜合性能優(yōu)良,主要表現(xiàn)為:成形時(shí)壓制壓力分布平穩(wěn),壓坯密度高達(dá)6.57g/cm3,燒結(jié)坯外徑硬度HRB67-73,外法線硬度HRB45-50,壓潰力9.77-10.40 kN,從而驗(yàn)證了還原鐵粉生產(chǎn)工藝控制的科學(xué)性和有效性。
[Abstract]:Iron base powder metallurgy automobile shock absorber parts are subjected to alternating load during the process of use, which requires very high comprehensive performance, including fatigue strength. High-compressibility iron-base powder is the key to ensure that this kind of parts have good comprehensive properties. The compressibility of the reduced iron powder prepared by Anhui Masteel Powder Metallurgy Co., Ltd. using the existing process of reducing iron powder production is generally less than 6.80g / cm ~ 3, which is not conducive to the complete densification and sintering of powder metallurgy products. It is difficult to obtain powder metallurgy automobile shock absorber structure with excellent comprehensive performance. In order to solve this problem, the effects of the above factors on the compressibility of reduced iron powder are systematically studied from the following aspects: the first reduction temperature, the second reduction temperature and the atmosphere, the batch proportioning and so on, and the key to control the compressibility of the reduced iron powder. The research results are applied to the piston of powder metallurgy automobile shock absorber. The main conclusions are as follows: (1) the highest reduction temperature in the tunnel kiln is 1160 鈩，

本文編號(hào)：2138216