The Leco from North of La Paz were considered to have disappeared by the end of the 20th century; however in 1997, two groups of Leco re-emerged independently from each other, one in Larecaja and one in Apolo. In the former the claim was less violent than in the latter, where Quechua peasants share language, culture and kinship, and refuse to recognize the land rights and the identity of their “Indigenous Leco” neighbours. The thesis aims to understand ethnohistorically both resurgences, and tries to go beyond essentialism to understand the heterogeneous melting pot from where the Apoleños come. Apolobamba, because it connects highlands and lowlands, received Andean influences (puquina, aymara and quechua) early on. Its inhabitants, the Chuncho of the Incas then the Spaniards, show hybrid ethnolinguistic and socio-cultural features. The ethnic diversity was reduced in the 18th century Franciscan Missions, where the ethnolinguistic border between an Andean South and the “savages” of the North was drawn at the Tuichi river. The liberal Republican period, with the construction of a national identity, once again shrank regional diversity and increased “Andeanization”. Apolistas and then Apoleños emerged from these interethnic mixes defined more geographically than ethnically. The Leco revival happens in an auspicious national and international context, but the Leco language was still spoken two or three generations ago on the Mapiri's banks. It raises the question of social transformation and continuity: are we dealing with a case of acculturation, ethnogenesis, camouflage or resistance?

Les Leco du nord de La Paz étaient considérés disparus à la fin du XXe siècle, pourtant en 1997, deux groupes resurgissent séparément pour compter au total 9006 Leco en 2013.Si la résurgence ne fut pas conflictuelle à Guanay où se parlait une langue leca il y a 50 ans, elle fut violente à Apolo, où les Leco partagent langue, culture et parenté avec les paysans quechua voisins qui contestent à la fois leur droit à un territoire et leur condition de « vrais » Indiens.Afin de dépasser les essentialismes, la thèse tente de comprendre ces résurgences à partir de l’étude ethnohistorique de la région et de saisir les brassages hétéroclites d’où sont issus les Apoleños (indigènes Leco et paysans).Véritable nœud entre hautes et basses terres, Apolobamba a reçu très tôt des apports andins (puquina, aymara et quechua). Ses habitants, les Chuncho des Incas puis des Espagnols, présentent tous des traits linguistiques et socioculturels hybrides. La diversité ethnique se réduit dans les missions franciscaines du XVIIIe siècle, instaurant la frontière ethnolinguistique du Tuichi entre un sud plus andin et les « sauvages » du nord. Le libéralisme de la période républicaine et la construction identitaire nationale amenuisent encore la diversité régionale et accélèrent l’« andinisation ». De ces brassages émergent les Apolistas puis les Apoleños ; des identités toponymiques plus qu’ethniques. La renaissance des Leco s’inscrit dans un panorama national et international favorable, mais une langue leco se parlait encore il y a deux à trois générations sur les bords du Mapiri. Se pose le problème des transformations des sociétés et de leur continuité : métissages, acculturation, ou bien ethnogenèse, camouflage et résistance ? / The Leco from North of La Paz were considered to have disappeared by the end of the XXth century ; however in 1997, two groups of Leco re-emerged independently from each other, one in Larecaja and one in Apolo. In the former the claim was less violent than in the latter, where Quechua peasants share language, culture and kinship, and refuse to recognize the land rights and the identity of their “Indigenous Leco” neighbours.The thesis aims to understand ethnohistorically both resurgences, and tries to go beyond essentialism to understand the heterogeneous melting pot from where the Apoleños come.Apolobamba, because it connects highlands and lowlands, received Andean influences (puquina, aymara and quechua) early on. Its inhabitants, the Chuncho of the Incas then the Spaniards, show hybrid ethnolinguistic and socio-cultural features. The ethnic diversity was being reduced in the 18th century Franciscan Missions, where the ethnolinguistic border between an Andean South and the “savages” of the North was drawn at the Tuichi river. The liberal Republican period, with the construction of a national identity, once again shrunk regional diversity and increased “andeanization”. Apolistas and then Apoleños emerged from these interethnic mixes defined more geographically than ethnically.The Leco revival happens in an auspicious national and international context, but the Leco language was still spoken two or three generations ago on the Mapiri’s banks. It raises the question of social transformation and continuity: are we dealing with a case of acculturation, ethnogenesis, camouflage or resistance?

<p>Duplex stainless steels are a very attractive alternative to austenitic grades due to their higher strength and good corrosion performance. The austenitic grades can often be welded autogenously, while the duplex grades normally require addition of filler metal. This is to counteract segregation of important alloying elements and to give sufficient austenite formation to prevent precipitation of chromium nitrides that could have a negative effect on impact toughness and pitting resistance. The corrosion performance of the recently-developed lean duplex stainless steel LDX 2101 is higher than that of 304 and can reach the level of 316. This thesis summarises pitting resistance tests performed on laser and gas tungsten arc (GTA) welded LDX 2101. It is shown here that this material can be autogenously welded, but additions of filler metal, nitrogen in the shielding gas and use of hybrid methods increases the austenite formation and the pitting resistance by further suppressing formation of chromium nitride precipitates in the weld metal. If the weld metal austenite formation is sufficient, the chromium nitride precipitates in the heat-affected zone (HAZ) could cause local pitting, however, this was not seen in this work. Instead, pitting occurred 1–3 mm from the fusion line, in the parent metal rather than in the high temperature HAZ (HTHAZ). This is suggested here to be controlled by the heat tint, and the effect of residual weld oxides on the pitting resistance is studied. The composition and the thickness of weld oxide formed on LDX 2101 and 2304 were determined using X-ray photoelectron spectroscopy (XPS). The heat tint on these lean duplex grades proved to contain significantly more manganese than what has been reported for standard austenitic stainless steels in the 300 series. A new approach on heat tint formation is consequently presented. Evaporation of material from the weld metal and subsequent deposition on the weld oxide are suggested to contribute to weld oxide formation. This is supported by element loss in LDX 2101 weld metal, and nitrogen additions to the GTA shielding gas further increase the evaporation.</p><p> </p>

Duplex stainless steels are a very attractive alternative to austenitic grades due to their higher strength and good corrosion performance. The austenitic grades can often be welded autogenously, while the duplex grades normally require addition of filler metal. This is to counteract segregation of important alloying elements and to give sufficient austenite formation to prevent precipitation of chromium nitrides that could have a negative effect on impact toughness and pitting resistance. The corrosion performance of the recently-developed lean duplex stainless steel LDX 2101 is higher than that of 304 and can reach the level of 316. This thesis summarises pitting resistance tests performed on laser and gas tungsten arc (GTA) welded LDX 2101. It is shown here that this material can be autogenously welded, but additions of filler metal, nitrogen in the shielding gas and use of hybrid methods increases the austenite formation and the pitting resistance by further suppressing formation of chromium nitride precipitates in the weld metal. If the weld metal austenite formation is sufficient, the chromium nitride precipitates in the heat-affected zone (HAZ) could cause local pitting, however, this was not seen in this work. Instead, pitting occurred 1–3 mm from the fusion line, in the parent metal rather than in the high temperature HAZ (HTHAZ). This is suggested here to be controlled by the heat tint, and the effect of residual weld oxides on the pitting resistance is studied. The composition and the thickness of weld oxide formed on LDX 2101 and 2304 were determined using X-ray photoelectron spectroscopy (XPS). The heat tint on these lean duplex grades proved to contain significantly more manganese than what has been reported for standard austenitic stainless steels in the 300 series. A new approach on heat tint formation is consequently presented. Evaporation of material from the weld metal and subsequent deposition on the weld oxide are suggested to contribute to weld oxide formation. This is supported by element loss in LDX 2101 weld metal, and nitrogen additions to the GTA shielding gas further increase the evaporation. / QC 20101126