A Study Of Mechanical Properties And Microstructure About Quenched And Tempered Steels And Non-quenched And Tempered Steels

Quenched and tempered steels are applied well in machine manufacture industry, because of their fine overall mechnical properties, namely, fine cooperate of intension and toughness, it is a structure steel material with abroad application. Quenched ang tempered steels are classified carbon quenched and tempered steels and alloy quenched and tempered steels.Quench and temper heat treatment is also quench and high temperature temper, attaining martensite after steels being quenched, and attaining sorbite after steels being tempered. Sorbite is the mixture polygonal ferrite and course grainy cementite, it has higher intension, plastic and toughness.But, Quench and temper heat treatment will appear the defects of heat treatment, such as quench crack, quench craze, quench distortion, oxidation, decarbonization, temper brittleness, ununiformity of hardness etc, further more some defects can't be renovated. Quench and temper heat treatment technice is complicated, pollutes environment, high cost, consumes energy sources largely. For conquering these shortcomings, various country in the world begin study and produce non quenched and tempered, from 70s last centry, insisting on the ideas of economizing energy sources, after Germany produce the first non-quenched and tempered steel 49MnVS3. Because non quenched and tempered steel has the virtue of economizing energy sources, reducing pollution, low cost and so on, it is applied to make mechanical jparts, moreover applicationg field continue broaden. Abroad, the country studing and appling non-quenched and tempered better are Germany, Sweden and Japan. China begin study non-quenched and tempered form"the sixth five year plan", makeobvious progress in its study, production and application. China produce auto connecting rod, bendt shaft, machine tool principal axis, etc.Comparing to quenched and tempered steel, non-quenched and tempered steel has many virtues in mecannical properties, technic properties and technology ecomony, and good application foreground. One of important application is auto connecting rod material. My paper contrast and analyze mechanical properties and microstructure about quenched and tempered steel and non-quenched and tempered steel, and combining to scientific research item about equipment and technics applied to precisely shape auto connecting rod, research object is quenched and tempered and non-quenched and tempered, which are connecting rod material,concretely, I choose two quenched and tempered 45, 40Cr, and two non-quenched and tempered C70S6,YF40MnV in common use, and contrast and analyze them from material composition ,microstructure etc, and combining heat treatment technic and forging technic of each material in use, and compare to study microstructure and properties before heat treatmeng and after, before forging and after.As the study base analyzing properties and microstructure about quenched and tempered steel and non-quenched and tempered steel, my paper first analyzing formation process and properties characteristic about each microstructure of steel, mechanical properties criterion, namely intension, plasticity and toughness criterion, and inhenrence relation between each micristructure and mechanical properties.Heat treatment technic about quenched and tempered steel is more complex, technic parameters during quench or temper, such as heat temperature cool mode etc, effect and decides microstructure and properties, and have definite rule. We should summarize these rules constantly, and so that guide manufacture use it. The effect of quench and temper heat treatment technic parameter on microstructure and property is analyzed detailed in my paper. I analyze hardenability of steel, the effect of quench heat temperature, quenchcool medium, temper temperature, temper cool mode etc on microsturcture and property of quenched and tempered steel, and analyze quench and temper technic from chemical composition, phase compose etc, and introduce some new technic strengthen and toughen quenched and tempered steel.It can obtain mechanical property which quenched and tempered steel is quenched and tempered treated, which untreated non quenched and tempered steel. In use non-quenched and tempered, these circs often happen, which intension is enough, but toughness is insufficiency. Because non-quenched and tempered with ferrite-pearlite microsturcture is often used, I analyze strengthen and toughen mechanism, from fracture circus of steel, and summarize stenghen and toughen mechanism of non-quenched and tempered, and analyze some good strengthen and toughen approaches, by the example of non-quenched and tempered with ferrite-pearlite microsturcture.According to form technic about connecting rod, it is mainly forged machine, which quenched and tempered steel and non-quenched and tempered steel connecting rod. In my tutor's patent thought, connecting rod is cross-wedge-rolled preformed, and rolled precise form.Roll have characteristic of roll forging, further more cross-wedge-roll and roll belong to two special forging technic. Forging technic is discussed about quenched and tempered steel and non-quenched and tempered steel in my paper, the effect of different forging technic parameter on microstructure and property about quenched and tempered steel and non-quenched and tempered steel is also discussed. Physical simulation technic is introduced used in the forging technic, and heat simulation test equipment and simulating connecting rod forging process by combining physical simulation to numerical simulation is also introduced.My paper is basal research about mechanical property and microstructure of quenched and tempered steel and non-quenched and tempered steel, and combining my tutor's patent thought and scientific research item in super plastic and plastic research institute. Connecting rod material about quenchedand tempered steel and non-quenched and tempered is choosed and made contrast and analysis, from material composition, mocrosturcture and mechanical property etc. The effect of heat treatment technic, forging technic on microstructure and property about the two steels is analyzed. The aim in my paper is on the base of analyzing microstructure and property about quenched and tempered steel and non-quenched and tempered steel, analysis and research is made concretely, aiming at one of their important application, namely auto connecting rod material. I hope these can offer some reference for establishing connecting rod manufacture technic, and do a little contribution for directing practical manufacture.