PVP高分子淬火液參數及奈米顆粒添加物對鋼料淬火特性之影響

The Effect of PVP Polymer Quenchant Parameters and Nano-Particle Additives on Quenching Characteristics for Steels

童順晨(Shun-Chen Tong)

指導教授 ： 曾春風

國立虎尾科技大學/工程學院/材料科學與綠色能源工程研究所/碩士(2014年)

摘要

本研究旨在探討PVP 高分子淬火液濃度、流速、溫度及奈米顆粒添加物等參數對數種鋼料淬火特性的影響。藉由改變PVP高分子淬火液參數以及添加蒙脫土奈米顆粒後，以了解這些參數對上述數種鋼料硬度分佈、硬化深度、淬火變形量及淬火組織的影響，並在硬化情況下尋找降低淬火變形量之最佳淬火液參數。最後與傳統油(油溫70°C)油淬火比較其淬火特性及淬火變形量的改善情形，以評估PVP 高分子淬火液取代傳統油淬火介質應用在鋼料淬火的可行性。
實驗結果顯示，淬火液溫度在室溫26°C下、攪拌流速固定，高分子濃度由10%提高至30%，各種鋼種硬度皆會降低。硬化能較好的JIS-SNCM439、JIS-SKD61其硬度下降趨勢並不大；中等硬化能的鋼 JIS-SCM440硬度降低趨勢較顯著；硬化能較差的鋼JIS-S45C硬度也會有顯著的降低。淬火液溫度在室溫26°C下、高分子濃度固定，隨著攪拌流速的增加，各鋼種硬度將隨之增加；對於硬化能較好的鋼JIS-SNCM439、JIS-SKD61硬度增加幅度不大；對於中等硬化能以及硬化能較差的鋼JIS-SCM440、JIS-S45C隨著流速增加可大幅提升其硬化深度。淬火液溫度由室溫26°C上升到40°C時，將造成試棒淬火後的硬度下降，硬化能越差的鋼影響越大；在高分子淬火液中添加蒙脫土奈米顆粒後，對硬化能較好的鋼JIS-SNCM439、JIS-SKD61試樣淬火後硬度略微降低，顯然此蒙脫土奈米顆粒有阻隔熱傳的效果。
淬火液溫度在室溫26°C下、攪拌流速固定，隨著高分子濃度由10%提高至30%，硬化能較好的鋼JIS-SNCM439、JIS-SKD61及硬化能中等的鋼JIS-SCM440試棒單位長度最大偏轉量將會降低，但是濃度增加至20%以後效果則不顯著；對於硬化能較差的鋼JIS-S45C，高分子濃度由10%提高至20%，試棒單位長度最大偏轉量將隨之降低，但是濃度增加至20%時，試棒橫截面硬度無法達到硬化標準。適當的攪拌流速下可降低淬火變形量，對於各鋼種而言，流速在0.3m/sec，可使試棒單位長度最大偏轉量降至最低；淬火液溫度由室溫26°C提升到40°C時，可使試棒單位長度最大偏轉量降低。在高分子淬火液中添加蒙脫土奈米顆粒後，能有效的降低硬化能較好的鋼JIS-SNCM439、JIS-SKD61試棒單位長度最大偏轉量。
本研究中各鋼種在高分子淬火液最佳參數及傳統油淬參數下淬
火得相近的淬火硬度，PVP高分子淬火液適用於JIS-SNCM439、JIS-SKD61，但不適用於JIS-SCM440、JIS-S45C之淬火硬化。本研究中JIS-SNCM439及JIS-SKD61、JIS-SCM440、JIS-S45C等四種鋼料降低淬火變形量之淬火液參數是在室溫下、攪拌流速0.3m/sec，高分子濃度分別為20%(並添加4%蒙脫土奈米顆粒)、20%、15%。

關鍵字

PVP 高分子淬火液 ； 蒙脫土奈米顆粒 ； 濃度 ； 攪拌流速 ； 淬火變形量 ； 單位長度偏轉量

並列摘要

The purpose of this article is to investigate the effect of PVP type polymer quenchant parameters including concentration, fluid agitation velocity, temperature, and nano-particle additives on quenching characteristics for several selected steels. By changing the parameters of PVP polymer quenchant and adding montmorillonite nano-particle additives, we reveal the effect of these parameters on the hardness distribution, hardening depth, quenching distortion and microstructures for several selected steels, and also look for the optimum quenchant parameters to reduce the quenching distortion based on hardenable condition. Finally, a comparison was conducted on the quenching characteristics and the improvement condition of quenching distortion between polymer quenchant quenching and conventional oil (temperature at 70 ° C) quenching in order to estimate the feasibility of PVP polymer quenching media to replace conventional mineral oil on quenching application for steels.
The experimental results show that quenched hardness of all selected steels in this study is decreased as the polymer concentration of quenchant is increased from 10% to 30% with fixed fluid agitation velocity at room temperature (26°C). Hardness decline of JIS-SNCM439 and JIS-SKD61 steels with high hardenability is not large; hardness downward tendency of middle hardenability steel JIS-SCM440 is obvious; and hardness of lower hardenability steel JIS-S45C will be significantly reduced, too. The hardness of all selected steels will increase as fluid agitation velocity of quenchant increases at room temperature (26°C); hardness increment margin is low for high hardenability steels JIS-SNCM439 and JIS-SKD61, and hardening depth of middle hardenability steel JIS-SCM440 and lower hardenability steel JIS-S45C can be significantly enhanced as fluid agitation velocity is increased. Hardness of quenched specimen will be reduced as quenchant temperature was raised from room temperature (26° C) to 40°C; the lower is the steel hardenability, the higher will be the effect result. Hardness of quenched specimens for high hardenability steels JIS-SNCM439 and JIS-SKD61 will decrease slightly as PVP polymer quenchant was added the additives of montmorillonite nano-particle; it is quite obvious that montmorillonite nano-particle has a barrier effect of heat transfer.
When polymer concentration is increased from 10% to 30% and fluid agitation velocity of quenchant is constant at room temperature (26 ° C), the maximum deflections of unit length of high hardenability steels JIS-SNCM439, JIS-SKD61 and middle hardenability steel JIS-SCM440 will reduce; but the effect is not obvious significantly as polymer concentration exceeds about 20%. Maximum deflection of unit length for lower hardenability steel JIS-S45C will decrease as the polymer concentration is increased from 10% to 20%; but cross-section hardness of specimen cannot achieve hardening standards as the concentration is increased to 20%. Proper fluid agitation velocity can reduce quenching distortion of specimen; maximum deflection of unit length for specimen can be reduced to minimum as fluid agitation velocity is at 0.3m/sec for above-mentioned several selected steels. When quenchant temperature was raised from room temperature (26°C) to 40°C, maximum deflection of unit length for specimen will be decreased. Maximum deflection of unit length for high hardenability steels JIS-SNCM439 and JIS-SKD61 can be effectively reduced as montmorillonite nano-particle was added to PVP type polymer quenchant.
The selected steels were quenched by using optimum polymer quenchant parameter and conventional oil quenchant parameter in this study, quenched steels will obtain approximate hardness. PVP type polymer quenchant is applicable to quenching hardening for JIS-SNCM439 and JIS-SKD61, but is not applicable for quenching of JIS-SCM440 and JIS-S45C. In this study, quenchant parameters of reducing quenching distortion for JIS-SNCM439 and JIS-SKD61, JIS-SCM440, JIS-S45C is respectively polymer concentration at 20% (and adding 4% montmorillonite nano- particle), 20%, 15% with fluid agitation velocity 0.3m/sec at room temperature (26 ° C).

並列關鍵字

PVP polymer quenchant ； concentration ； quenching characteristics ； montmorillonite ； quenching distortion ； fluid agitation velocity ； deflection of unit length

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