Why does the brake drum fail in operation?
- Categories:Industry Information
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- Time of issue:2019-08-21 08:41
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(Summary description)Intheuseofautomobilebrakedrum,ifthefailureofbrakedrumoccurs,itwillbringusdanger.Whatcausesthefailureofbrakedruminoperation?Nowlet'sgettoknowitwithXiaobian.Samplingandanalysisoffailurebrakedrum(includinglongitudinalcracking,creepcrackingandhardspotbrakedrum),theworkingenvironmentofbrakedrumisrelativelybad,undertheimpactthermalstresscausedbyfrequentbraking(sentencebrakingisequivalenttoimpactthermalstress),inonecase,therateofheatingorcoolingisgreaterthan93ortherateofheatingandcoolingisfastandHeatingissmallanduniform,andheatshockoccurswhentemperaturecrossesover102incastings.Becausethebrakedrumheatdissipationconditionsaresmall,leadingtotemperaturerise.Whenthetemperaturereachesabout730C,ifthestabilityofpearliteissmall,itwilldecompose,volumewillexpandandcausephasechangestress.Ifthepeakvalueofthesuperpositionofthediurnalstressandthermalstressexceedsthethermalfatiguestress,thermalfatiguecrackingwilloccur.Similarly,ifthethermalfatiguestressexceedsthethermalfatiguestress,thermalfatiguecrackingwilloccur.Atthistime,theenvironmentalhistoryisbadorthethermalconditionispoor,andthetemperaturerisesabovetheeutectoidtransformationtemperaturetoformaustenite.Understrongcoldconditions,suchaswatercoolingorstrongwindcooling,hardeningphasessuchasmartensite,bainiteorsorbitewillbeformed.Thisiswhythefailurebrakedrumcracksandformshardspotsonthesurfaceatthesametime.Because.
Why does the brake drum fail in operation?
(Summary description)Intheuseofautomobilebrakedrum,ifthefailureofbrakedrumoccurs,itwillbringusdanger.Whatcausesthefailureofbrakedruminoperation?Nowlet'sgettoknowitwithXiaobian.Samplingandanalysisoffailurebrakedrum(includinglongitudinalcracking,creepcrackingandhardspotbrakedrum),theworkingenvironmentofbrakedrumisrelativelybad,undertheimpactthermalstresscausedbyfrequentbraking(sentencebrakingisequivalenttoimpactthermalstress),inonecase,therateofheatingorcoolingisgreaterthan93ortherateofheatingandcoolingisfastandHeatingissmallanduniform,andheatshockoccurswhentemperaturecrossesover102incastings.Becausethebrakedrumheatdissipationconditionsaresmall,leadingtotemperaturerise.Whenthetemperaturereachesabout730C,ifthestabilityofpearliteissmall,itwilldecompose,volumewillexpandandcausephasechangestress.Ifthepeakvalueofthesuperpositionofthediurnalstressandthermalstressexceedsthethermalfatiguestress,thermalfatiguecrackingwilloccur.Similarly,ifthethermalfatiguestressexceedsthethermalfatiguestress,thermalfatiguecrackingwilloccur.Atthistime,theenvironmentalhistoryisbadorthethermalconditionispoor,andthetemperaturerisesabovetheeutectoidtransformationtemperaturetoformaustenite.Understrongcoldconditions,suchaswatercoolingorstrongwindcooling,hardeningphasessuchasmartensite,bainiteorsorbitewillbeformed.Thisiswhythefailurebrakedrumcracksandformshardspotsonthesurfaceatthesametime.Because.
- Categories:Industry Information
- Author:
- Origin:
- Time of issue:2019-08-21 08:41
- Views:
In the use of automobile brake drum, if the failure of brake drum occurs, it will bring us danger. What causes the failure of brake drum in operation? Now let's get to know it with Xiaobian. Sampling and analysis of failure brake drum (including longitudinal cracking, creep cracking and hard spot brake drum), the working environment of brake drum is relatively bad, under the impact thermal stress caused by frequent braking (sentence braking is equivalent to impact thermal stress), in one case, the rate of heating or cooling is greater than 93 or the rate of heating and cooling is fast and Heating is small and uniform, and heat shock occurs when temperature crosses over 102 in castings. Because the brake drum heat dissipation conditions are small, leading to temperature rise. When the temperature reaches about 730 C, if the stability of pearlite is small, it will decompose, volume will expand and cause phase change stress. If the peak value of the superposition of the diurnal stress and thermal stress exceeds the thermal fatigue stress, thermal fatigue cracking will occur. Similarly, if the thermal fatigue stress exceeds the thermal fatigue stress, thermal fatigue cracking will occur. At this time, the environmental history is bad or the thermal condition is poor, and the temperature rises above the eutectoid transformation temperature to form austenite. Under strong cold conditions, such as water cooling or strong wind cooling, hardening phases such as martensite, bainite or sorbite will be formed. This is why the failure brake drum cracks and forms hard spots on the surface at the same time. Because.
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