440A vs 440B vs 440C Stainless Hlau: Lub Siab -Carbon Martensitic Series rau Kev Siv Hnav

 

Dab tsi yog qhov txhais cov tshuaj lom neeg thiab ua rau lub zog hardness ntawm 440A, 440B, thiab 440C?
Tag nrho peb qib sib koom ua ke ntawm 16-18% chromium. Lawv qhov sib txawv yog nyob rau hauv cov ntsiab lus carbon:440Amuaj 0.60-0.75% C,440Bmuaj 0.75-0.95% C, thiab440Cmuaj 0.95-1.20% C. Cov pa roj carbon ntau ntxiv no tso cai rau ntau dua ntawm cov tawv chromium carbides. Yog li ntawd, qhov siab tshaj plaws hardness nce los ntawm kwv yees li HRC 55-57 rau 440A, mus rau HRC 56-58 rau 440B, thiab mus txog HRC 58-60 rau 440C. Thaum hardness nce, cuam tshuam toughness thiab tsis kam mus rau chipping txo.

Yuav ua li cas daim ntawv thov tus thawj tsis ua hauj lwm hom coj kev xaiv ntawm peb qib no?
Kev xaiv yuav tsum tau tsav los ntawm qhov kev hem thawj tseem ceeb:Rau Hnav / Abrasion:Xaiv raws li hardness . 440C yog qhov zoo tshaj plaws rau kev hnav hnyav (cov kabmob, siab- hnav cov hniav). 440B muaj qhov sib npaug zoo.Rau Impact/Shock:Ua ntej tshaj qhov tawv nqaij. 440A yog qhov zoo tshaj plaws rau cov cuab yeej uas tej zaum yuav poob los yog raug kev nyuaj siab rau sab nraud (screwdrivers, qee qhov txiav).Rau Corrosion:Txhua tus muaj qhov zoo sib xws, nruab nrab corrosion kuj. Yog tias corrosion yog qhov kev txhawj xeeb loj, qib sib txawv (xws li, 420) yuav tsim nyog dua. Kev phais scalpel yuav siv 440C rau ntug tuav, thaum lub vaj txiav yuav siv 440A rau kev poob siab.

Dab tsi yog qhov tseem ceeb ntawm kev kho cua sov rau txhua tus 440 series steels?
Txhua tus xav tau kev kho cua sov kom ua tiav lawv cov khoom: austenitizing, quenching, thiab tempering. Cov qib carbon ntau dua yuav tsum muaj qhov kub austenitizing ntau dua kom yaj cov carbide ntau ntxiv. Tag nrho cov no tsis tshua muaj kev cuam tshuam rau decarburization (poob carbon deg) thaum kho cua sov, uas tsim cov tawv nqaij mos. Yog li ntawd, kev tiv thaiv huab cua (nqus lossis tswj roj) kev kho cua sov yog pom zoo kom ua tiav qhov ntev. Ntau lub voj voog tempering feem ntau yog siv los xyuas kom muaj kev ruaj ntseg thiab hloov pauv tau khaws cia austenite.

Hais txog machinability thiab grindability, lawv piv li cas?
Machinability nyob rau hauv lub annealed mob yog ncaj ncees rau tag nrho cov tab sis txo nrog ntau dua carbon thiab carbide cov ntsiab lus . 440A feem ntau yog qhov yooj yim tshaj rau tshuab. Tom qab hardening, lawv yog unmachinable nrog cov pa cuab yeej; kev ua tiav yog ua tiav los ntawm kev sib tsoo. Grindability kuj tseem nyuaj nrog ntau dua hardness. Kev siv cov kev sib tsoo kom raug thiab cov txheej txheem kom tsis txhob muaj cua sov ntau dhau yog qhov tseem ceeb los tiv thaiv tempering lossis tawg ntawm qhov ua tiav.

Cov lus qhia tshwj xeeb kawg dab tsi ua kom koj tau txais qib raug thiab ua haujlwm tau zoo?
Nco ntsoov qhia qhov tseeb AISI lub npe: 440A, 440B, lossis 440C. Tsis txhob cia li hais tias "440 stainless," vim qhov no tuaj yeem ua rau kom tau txais cov khoom yooj yim tshaj plaws (feem ntau 440C) uas yuav tsis zoo. Ntawm kev yuav khoom, kuj qhia qhov yuav tsum tau ua (piv txwv li, "Annealed" lossis "Hardened thiab Tempered rau HRC 58-60"). Rau cov ntawv thov tseem ceeb, xav tau daim ntawv pov thawj cov khoom siv thiab txiav txim siab qhia cov khoom siv hluav taws xob siv hluav taws xob (xws li 440C-VAR) txhawm rau txhim kho purity thiab toughness.