本文選題：汽車(chē)卷簧 + 脫碳　； 參考：《安徽工業(yè)大學(xué)》2014年碩士論文

【摘要】：彈簧鋼是一種重要的機(jī)械設(shè)備基礎(chǔ)零件制造材料,現(xiàn)已廣泛應(yīng)用于航空航天、汽車(chē)、鐵路等諸多領(lǐng)域。由于彈簧鋼的工作條件十分苛刻,對(duì)彈簧鋼的性能要求就十分嚴(yán)格。其中,抗疲勞和抗彈減性減退是影響彈簧鋼設(shè)計(jì)應(yīng)力的主要因素,與其內(nèi)在質(zhì)量(化學(xué)成分、純凈度)、表面質(zhì)量(裂紋、凹坑、脫碳)以及微觀組織有密切關(guān)系。因此,要求彈簧鋼不僅具有較高的強(qiáng)度、良好的塑韌性,而且還要有一定淬透性、較低的脫碳敏感性和良好的加工性能。本文以常用于生產(chǎn)汽車(chē)安全帶卷簧用彈簧鋼Super6和SK5為研究對(duì)象,首先研究了兩種實(shí)驗(yàn)鋼的表面脫碳規(guī)律,以避免在熱軋過(guò)程中發(fā)生表面脫碳:實(shí)驗(yàn)室模擬兩種彈簧鋼的加熱工藝,分析加熱溫度和保溫時(shí)間對(duì)其脫碳層深度的影響。實(shí)驗(yàn)結(jié)果表明:彈簧鋼Super6的脫碳敏感性要明顯高于彈簧鋼SK5的。對(duì)于彈簧鋼Super6可在700℃以上盡量減少加熱時(shí)間,950℃到1100℃內(nèi)迅速升溫,1100℃以上應(yīng)盡量減少保溫時(shí)間,且熱卷溫度應(yīng)在700℃以下;對(duì)于彈簧鋼SK5可在950℃以上盡量減少加熱時(shí)間,1100℃以上快速升溫,熱卷溫度控制在950℃以下即可。合理制定熱處理工藝,以穩(wěn)定提高兩種實(shí)驗(yàn)鋼的疲勞壽命。利用JMatPro軟件模擬了彈簧鋼Super6和SK5的CCT曲線。根據(jù)JMatPro軟件預(yù)測(cè)結(jié)果,設(shè)計(jì)正交熱處理實(shí)驗(yàn)方案,并運(yùn)用極差分析進(jìn)一步討論不同熱處理工藝對(duì)兩種實(shí)驗(yàn)鋼力學(xué)性能(屈服強(qiáng)度、抗拉強(qiáng)度和延伸率)的影響規(guī)律,以得出兩種彈簧鋼的最佳熱處理工藝。兩種實(shí)驗(yàn)鋼的最佳熱處理工藝為:彈簧鋼Super6在880℃淬火,保溫30 min后油淬,在430℃回火,保溫60 min空冷;彈簧鋼SK5在850℃淬火,保溫30 min后油淬,在400℃回火,保溫40 min后空冷。對(duì)比兩種實(shí)驗(yàn)鋼回火后的微觀組織,分析導(dǎo)致兩種彈簧鋼疲勞壽命存在差異性的原因。通過(guò)對(duì)比發(fā)現(xiàn):熱處理后,兩種實(shí)驗(yàn)鋼的組織均是回火屈氏體,彈簧鋼SK5較彈簧鋼Super6的回火屈氏體更細(xì)小,碳化物分布更彌散,位錯(cuò)密度也更高;彈簧鋼Super6中存在大尺寸的未溶碳氮化物顆粒;彈簧鋼Super6中的形變織構(gòu)和再結(jié)晶織構(gòu)密度均大于彈簧鋼SK5中的,特別是{113}110和{331}110織構(gòu)明顯增強(qiáng)。兩種彈簧鋼微觀組織的不同,最終導(dǎo)致兩者疲勞性能差異很大。結(jié)果表明:經(jīng)過(guò)優(yōu)化熱處理工藝處理過(guò)的兩種彈簧鋼,機(jī)械性能均滿足要求,其中彈簧鋼SK5的疲勞壽命大于40萬(wàn)次,彈簧鋼Super6的疲勞壽命大于10萬(wàn)次,均達(dá)到了高品質(zhì)汽車(chē)安全帶卷簧的疲勞壽命標(biāo)準(zhǔn)。
[Abstract]:Spring steel is an important manufacturing material for basic parts of machinery and equipment, which has been widely used in aerospace, automobile, railway and many other fields. Because the working condition of spring steel is very harsh, the performance requirement of spring steel is very strict. Among them, anti-fatigue and anti-elasticity decrease are the main factors that affect the design stress of spring steel, which is closely related to the internal quality (chemical composition, purity, surface quality (crack, pit, decarburization) and microstructure). Therefore, spring steel not only has high strength, good plastic toughness, but also has certain hardenability, low decarburization sensitivity and good processability. In this paper, the surface decarbonization of two kinds of experimental steels, Super6 and SK5, is studied. In order to avoid surface decarbonization during hot rolling, the heating process of two spring steels was simulated in laboratory, and the effects of heating temperature and holding time on the depth of decarburization layer were analyzed. The experimental results show that the decarburization sensitivity of spring steel Super6 is higher than that of spring steel SK5. For spring steel Super6, the heating time should be reduced as much as possible in the range of 700 鈩，

本文編號(hào)：1945150