农业工程学报
農業工程學報
농업공정학보
2015年
1期
53-57
,共5页
农业机械%显微组织%淬火%农机刀具%预热处理%激光淬火%激光熔凝%性能
農業機械%顯微組織%淬火%農機刀具%預熱處理%激光淬火%激光鎔凝%性能
농업궤계%현미조직%쉬화%농궤도구%예열처리%격광쉬화%격광용응%성능
agricultural machinery%microstructure%quenching%agricultural tool%preheat-treating%laser quenching%laser melting-hardening%property
针对农机刀具易于磨损，且强化处理工艺较复杂、成本较高的现状，在正火和淬火-中温回火预热处理65Mn钢上，分别进行激光淬火和激光熔凝加工，研究了激光加工后的组织结构及显微硬度的变化规律，并探讨了其影响因素。研究结果表明：激光强化组织由表层熔凝区（激光熔凝）、完全淬火区、不完全淬火区、热影响区组成；正火预热处理后激光强化组织的显微硬度要高于淬火-中温回火预热处理后激光强化组织的显微硬度，激光熔凝处理后硬化区的显微硬度稍低于激光淬火硬化区的显微硬度。该研究为激光强化农机刀具的组织改善和性能提高提供了依据。
針對農機刀具易于磨損，且彊化處理工藝較複雜、成本較高的現狀，在正火和淬火-中溫迴火預熱處理65Mn鋼上，分彆進行激光淬火和激光鎔凝加工，研究瞭激光加工後的組織結構及顯微硬度的變化規律，併探討瞭其影響因素。研究結果錶明：激光彊化組織由錶層鎔凝區（激光鎔凝）、完全淬火區、不完全淬火區、熱影響區組成；正火預熱處理後激光彊化組織的顯微硬度要高于淬火-中溫迴火預熱處理後激光彊化組織的顯微硬度，激光鎔凝處理後硬化區的顯微硬度稍低于激光淬火硬化區的顯微硬度。該研究為激光彊化農機刀具的組織改善和性能提高提供瞭依據。
침대농궤도구역우마손，차강화처리공예교복잡、성본교고적현상，재정화화쉬화-중온회화예열처리65Mn강상，분별진행격광쉬화화격광용응가공，연구료격광가공후적조직결구급현미경도적변화규률，병탐토료기영향인소。연구결과표명：격광강화조직유표층용응구（격광용응）、완전쉬화구、불완전쉬화구、열영향구조성；정화예열처리후격광강화조직적현미경도요고우쉬화-중온회화예열처리후격광강화조직적현미경도，격광용응처리후경화구적현미경도초저우격광쉬화경화구적현미경도。해연구위격광강화농궤도구적조직개선화성능제고제공료의거。
At present, there exists a problem that the agricultural tools easily get worn. However, the common strengthening techniques have visible disadvantages, such as the complex process and comparatively high running cost. In order to solve the problem, the 65Mn steel was preheat-treated by the normalization or quenching + medium-temperature tempering. Subsequently, the preheat-treated 65Mn steel was strengthened by laser quenching or laser melting-hardening process with a YLR-6000 fiber laser. The microstructure was studied by optical microscope and scanning electronic microscope. The microhardness was measured using a Vickers-1000 microhardness tester with load of 1.96N and a dwelling time of 15s. Further, the controlling factors were investigated. The results showed that the preheat-treating and laser process had visible influences on the microstructure and property. In laser quenching, the microstructure was comprised of the entire quenching zone, part quenching zone and heat affected zone. The fine needle martensite was obtained in entire quenching zone by quenching + medium-temperature tempering + laser quenching. In the part quenching zone, the microstructures were fine needle martensite and troolstite. However, the fine needle martensite and a few ferrite were observed in entire quenching zone by normalization + laser quenching. In the laser melting-hardening process, the microstructure was made up of the surface melting zone, entire quenching zone, part quenching zone and heat affected zone. Compared with the microstructure of laser quenching, the surface melting zone was obtained in laser melting process, and the others were accorded with those in laser quenching. As for laser melting process, the depth of surface melting zone was within the range of 10-15 μm. In surface melting zone, the fine dendrite microstructure was got and the primary dendrite arm spacing was within the range of 4~6 μm. In addition, The microhardness of laser strengthening 65 Mn steel pretreated by normalization was relatively higher than that pretreated by quenching + medium-temperature tempering. It depended on the microstructure and its size. Moreover, the microhardness of laser melting-hardening was relatively lower than that of laser quenching. The microhardness of laser process could reach up to HV0.2830, about 1.5 times as much as that of common quenching + medium-temperature tempering. According to the working condition of agricultural tools, the surfaces needed to be hard and the interior parts needed to be with good toughness. The laser strengthening technique satisfied the request of steel property and simplified the running process. Therefore, in terms of agricultural tool strengthening approaches, the laser strengthening technique exhibits visible advantages and brings application prospects.
